HindlePower SCR series User manual

Operating and Service Instructions
SCR/SCRF SERIES
BATTERY CHARGER
SINGLE PHASE INPUT

i
IMPORTANT SAFETY INSTRUCTIONS
READ AND FOLLOW ALL SAFETY INSTRUCTIONS
1) Before using the battery charger, read all instruction and cautionary markings on:
A) battery charger, B) battery, C) equipment connected to charger and battery
2) This manual contains important safety and operating instructions, and therefore should be filed
for easy access.
3) Do not touch any insulated parts of the battery charger, especially the input and output connections,
as there is the possibility of electric shock.
4) During normal operation, batteries may produce explosive gas. NEVER smoke, use an open flame,
or create arcs in the vicinity of the charger or battery.
5) Maintain at least 1ft (0.3m) clearance from all obstructions on all sides of the battery charger.
6) Keep area in front of battery charger clear for at least 4ft (1.3m).
7) Connect or disconnect the battery only when the battery charger is off to prevent arcing or burning.
8) De-energize all AC and DC inputs to the battery charger before servicing.
9) Do not operate battery charger if it has been damaged in any way. Refer to qualified service
personnel only.
10) Do not disassemble battery charger. Only qualified service personnel should attempt repairs.
Incorrect reassembly may result in explosion, electrical shock, or fire.
11) Do not install the battery charger outdoors, or in wet or damp locations unless
specifically ordered for that environment.
12) Remove all jewelry, watches, rings, etc. before proceeding with installation.
SAVE THESE INSTRUCTIONS

ii
SCR/SCRF SERIES BATTERY CHARGER SPECIFICATIONS JF0026-00
MODEL No.
INPUT VOLTAGE Volts AC
SERIAL No.
FLOAT VOLTAGE Volts DC
SMART PART No. EQUALIZE VOLTAGE
Volts DC
(items A-F req’d) CORE (BB####) ABCDEFGHJKLMN
Pos. SMART PART
CODE
DWG
#SHT
#DESCRIPTION (X)
DWG
#SHT
#DESCRIPTION
UUNFILTERED OUTPUT (L1)
JE0121 1SURGE WITHSTAND FILTER (SWC) PER IEE-472
FFILTERED OUTPUT (L1/L2/C1)
EJ0083 4HIGH-LOW DC VOLTAGE ALARM RELAYS
A
EFILTERED-ELIMINATOR OUTPUT (L1/L2/C1/C2)
EJ0083 7HIGH-LOW DC VOLTAGE RELAYS & IND. LIGHTS
1120 VOLT AC INPUT (SINGLE PHASE ONLY)
EJ0088 4GROUND DETECTION IND. LIGHTS
2208/240 VOLT AC INPUT EJ0095 42% ACCURACY 3.5in AC VOLTMETER (1PH)
3220/240 VOLT AC INPUT (SINGLE PHASE ONLY)
EJ0096 40-72 HR. MANUAL EQUALIZE TIMER & IND. LIGHTS
4380/416 VOLT AC INPUT (THREE PHASE ONLY)
EJ0120 4BATTERY DISCHARGE RELAY & INDICATOR LIGHT
5480 VOLT AC INPUT EJ0121 42% ACCURACY 3.5in AC VOLTMETER (3PH)
6120/208/240 VOLT AC INPUT (SINGLE PHASE ONLY)
EJ0123 4COMMON ALARM BUZZER
B
7208/240/480 VOLT AC INPUT EJ0134 42% ACCURACY 3.5in AC AMMETER (1PH)
FDUAL DC FUSES (F1 / F2)
EJ0135 42% ACCURACY 3.5in AC AMMETER (3PH)
BSTANDARD DC CIRCUIT BREAKER (F1 / CB2)
EJ0137 4CURRENT LIMIT ALARM & IND. LIGHT (1 PH)
C
CCUSTOM DC PROTECTION EJ0137 5CURRENT LIMIT ALARM & IND. LIGHT (3 PH)
1MANUAL FLOAT / EQUALIZE SWITCH EJ0138 4DC ZERO-CENTER AMMETER -BATT/LOAD MONITOR
2EJ0093 4MANUAL FLOAT / EQUALIZE SWITCH & IND. LIGHTS EJ0143 4END OF DISCHARGE RELAY w/ INDICATOR LIGHT
3EJ0097 50-72 HR. MANUAL EQUALIZE TIMER EJ0143 5END OF DISCHARGE ALARM RELAY
4EJ0869 2MAN. EQUALIZE TIMER w/ F/E SWITCH & IND. LIGHTS EJ0145 5CABINET HEATER STRIPS
5EJ0131 4AC FAILURE AUTO-EQUALIZE TIMER & IND. LIGHTS EJ0155 1HIGH-LOW AC VOLTAGE RELAY & INDICATOR LIGHTS
D
0CUSTOM EQUALIZATION EJ0439 1OVER-TEMPERATURE ALARM RELAY w/ BUZZER
2% 2% ACCURACY 3.5in ANALOG DC METERS EJ0439 3OVER-TEMPERATURE ALARM RELAY w/ IND. LIGHT
1% 1% ACCURACY 3.5in ANALOG DC METERS EJ0615 1DC POWER ON INDICATOR LIGHT
SB 1% ACCURACY 4.5in SWITCHBOARD DC METERS EJ0803 1AC FAILURE RELAY w/ THERMAL TIME-DELAY
E
CMCUSTOM DC METERS EJ0826 1TEMPERATURE COMPENSATION (LEAD ACID)
PSTANDARD (COLOR-CODED PVC) WIRING EJ0895 10.1% ACCURACY 3.5in LED DIGITAL DC METERS
F
HCB0002 1&2 SIS TYPE (BLACK HYPALON) WIRING PER CB0002-00 EJ1234 1INPUT LIGHTNING ARRESTOR
AEJ0085 7AC POWER FAILURE RELAY & INDICATOR LIGHTS EJ1398 1EXTERNAL TEMPCO PROBE (LEAD ACID)
G
CCUSTOM AC FAILURE ALARM SPECIAL FLOOR MOUNTING
C1 EJ0837 1CASM PC BOARD w/ ONE (1) FORM-C CONTACTS SPECIAL RACK MOUNTING
C2 EJ0837 1CASM PC BOARD w/ TWO (2) FORM-C CONTACTS SPECIAL CABINET TYPE
HL EJ0083 7HIGH / LOW DC VOLTAGE ALARM & IND. LIGHTS CUSTOM TAG PLATE
ZC EJ0127 5CHARGER FAILURE ALARM (NO ADC) & IND. LIGHTS EJ5007 ENGRAVED FUNCTIONAL NAMEPLATES
H
HZ HLVA / CFA & IND. LIGHTS (EJ0083 & EJ0127) WHITE CHARACTERS ON BLACK BACKGROUND
SEJ0094 4GND. DET. SWITCH FOR DC VOLTMETER INDICATION BLACK CHARACTERS ON WHITE BACKGROUND
LEJ0089 5GND. DET. IND. LIGHTS w/ GROUND & LAMP TEST COPPER GROUND BUSS BARw/ LUG(S)
J
REJ0086 4GND. DET. RELAYS w/ RESET SWITCH & IND. LIGHTS JH0001 -07 FUNGUS PROOFING PER CA0004-00
FEJ0133 1PARALLEL CHGR OPER. w/ 2% LOAD SHARE (1PH) EXTRA INSTRUCTION MANUALS
K
FEJ0133 2PARALLEL CHGR OPER. w/ 2% LOAD SHARE (3PH)JH0003 CUSTOM DRAWING PACKAGE CAD DISK
HEJ0592 1HIGH VOLTAGE DC SHUTDOWN (1 PH) JH0002 -08 PARTS LIST REPORT (HASSOC)
L
HEJ0592 2HIGH VOLTAGE DC SHUTDOWN (3 PH) JH0002 -07 COPY OF TEST DATA PER NEMA PE 5-1985
REJ0141 1COMMON ALARM RELAY JH0002 -06 CERTIFIED TEST DATA PERNEMA PE 5-1985
BEJ0141 2COMMON ALARM RELAY & BUZZER JH0002 -03 CERTIFICATE OF CONFORMANCE
M
CEJ0967 1CASM PC BOARD COMMON ALARM BUZZER JH0002 -01 BURN-IN OR HEAT-RUN HOURS
DFE0237 DRIP SHIELDS -STYLE-1A, 1B & 2 CAB. (EB0220-222) JH0002 -00 IN-HOUSE INSPECTION BY OUTSIDE PERSONNEL
DEJ0692 DRIP SHIELDS -STYLE-3 CABINET (EB0123) JH0004 -01 EXPORT PACKING PER FS0001-00
DFE0447 DRIP SHIELDS -STYLE-4 CABINET (EB0163) CUSTOM PACKING
N
DEI0175 DRIP SHIELDS -STYLE-5 CABINET (EB0198) JH0004 -10 EXTENDED WARRANTY PER JF5001-00
GENERAL SPECIFICATIONS: ADDITIONAL FEATURES / OPTIONS / NOTES:
Regulation: + or -0.5% no-load to full-load
Regulation: + or -0.5% for + or -10% AC line variation
Regulation: + or -1% for combined load, line & temp. variations
Ambient Temperature Range: 0º C to 50º C
Relative Humidity: up to 95% without condensation
Altitude: up to 1,000m above sea level

iii
TABLE OF CONTENTS
Page No.
IMPORTANT SAFETY INSTRUCTIONS............................................................................................................i
SCR/SCRF BATTERY CHARGER SPECIFICATIONS................................................................................... ii
TABLE OF CONTENTS....................................................................................................................................... iii
SECTION II
1. Safety Notice.................................................................................................................................................. 1
2. Application..................................................................................................................................................... 1
3. Installation...................................................................................................................................................... 1
4. Placing Charger in Service............................................................................................................................. 2
5. Adjustments of Float & Equalizing Charge................................................................................................... 2
6. Manual Equalize Timer.................................................................................................................................. 3
7. Maintenance................................................................................................................................................... 3
8. Normal Performance...................................................................................................................................... 3
9. Description of Operation................................................................................................................................ 3
a. Four Major Sections.................................................................................................................................. 3
1. Power Transformer............................................................................................................................. 3
2. Rectifier Section ................................................................................................................................. 3
3. Control Module................................................................................................................................... 4
4. Filter Section....................................................................................................................................... 4
SECTION III
1. Troubleshooting Procedure............................................................................................................................ 4
2. Testing of Components .................................................................................................................................. 5
a. Power Transformer (T1)............................................................................................................................ 5
b. External Circuit Wiring............................................................................................................................. 6
c. Circuit Breakers......................................................................................................................................... 6
d. Rectifier Diodes......................................................................................................................................... 6
e. Surge Suppressors ..................................................................................................................................... 7
f. SCR Diodes............................................................................................................................................... 7
g. Control Module ......................................................................................................................................... 8
h. Current Sensing Resistor........................................................................................................................... 9
I. DC Voltmeter (M2)................................................................................................................................... 9
j. DC Ammeter (M1).................................................................................................................................... 9
k. Filter Capacitors........................................................................................................................................ 9
l. Internal Wiring........................................................................................................................................ 10

iv
SECTION IV
System Adjustments..............................................................................................................................................10
1. Voltage Adjustments and Response.............................................................................................................10
a. Float Adjustment .....................................................................................................................................11
b. Equalize Adjustment................................................................................................................................11
2. Current Limit Response and Adjustment .....................................................................................................11
a. Checks and Adjustments..........................................................................................................................11
b. Checks to Make if Malfunctioning..........................................................................................................12
SECTION V
Customer Options .................................................................................................................................................12
1. Ground Detection Circuits............................................................................................................................13
2. AC Power Failure Alarm Relay....................................................................................................................13
3. AC Voltmeter/AC Ammeter.........................................................................................................................14
4. High and Low DC Voltage Alarm Relays....................................................................................................14
5. Charger Failure Alarm Relay........................................................................................................................15
6. Battery Discharging Alarm Relay.................................................................................................................15
7. Equalize Timers............................................................................................................................................16
8. Common Alarm Buzzer................................................................................................................................17
9. Common Alarm Relay..................................................................................................................................17
10. Float and Equalize Indicating Lights............................................................................................................17
11. Parallel Charger Operation with Load Sharing ............................................................................................17
12. DC Zero-Center Ammeter for Battery/Load Monitoring.............................................................................18
13. High DC Voltage Charger Shutdown with Alarm Relay .............................................................................18
14. End of Discharge Alarm Relay.....................................................................................................................19
15. Current Limit Alarm Relay...........................................................................................................................19
16. Cabinet Heater Strips....................................................................................................................................19
17. High and Low AC Voltage Alarm Relays....................................................................................................19
18. Over-Temperature Alarm Relay...................................................................................................................20
19. Combined Alarm-Status Charger Monitor ...................................................................................................20
SECTION VI
1. Parts List -Mainframe..................................................................................................................................21
2. Parts List -Options.......................................................................................................................................23
SECTION VII
Table A -Troubleshooting Chart..........................................................................................................................27
Diagram -SCR / SCRF Battery Charger Mainframe Schematic (EH0537).........................................................28
Figure 1 -Component Layout for Control Module (GK0058).............................................................................29
Diagram -Schematic for Control Module (EH0573)...........................................................................................30
Figure 2 -Typical Waveforms of Control Module...............................................................................................31
Diagram -Power Transformer (T1) Schematics (EH0552)..................................................................................32
Table -Remote Alarm Terminal Block(s) Legend for TB3 and TB15 (EH0423) ...............................................33
Diagrams -Option Schematics .............................................................................................................................34
Electrical Ratings and Replacement Parts -Mainframe.......................................................................................53
Replacement Parts -Options.................................................................................................................................57

v

1
SECTION II
SINGLE PHASE SCR AND SCRF TYPE BATTERY CHARGER
INSTALLATION AND OPERATION
1. SAFETY NOTICE
THERE ARE DANGEROUS VOLTAGES WITHIN THE BATTERY CHARGER CABINET.
CAUTION! READ “IMPORTANT SAFETY INSTRUCTIONS” ON PAGE I.
a. Only qualified personnel should attempt to adjust or service this equipment.
b. Refer to instruction manual for service procedures and CAUTION notes.
2. APPLICATION
a. Specifications: The silicon controlled rectifier is designed to maintain a system voltage within + or -
0.5% of the set value without exceeding its rated output current. It will maintain + or -0.5% with input
voltage variations 10% above or below the rated input AC voltage and with 5% frequency variations.
The charger is designed, primarily, to operate only when connected to a battery load. It can be operated
as a battery eliminator into a resistive load up to full rated output at increased ripple. Filtered-type chargers
will have a ripple content less than 30 MV RMS under steady state conditions with the charger connected
to a battery having an 8-hour Amp-Hour rating of at least 4 times the full load current rating of the
charger. Other connected loads such as DC to DC power supplies or inverters, may put ripple on the
battery appreciably above 30 MV.
Unfiltered chargers should not be used with critical loads such as communication systems, amplifiers
and instrumentation systems, but should only be used for non-critical applications such as engine cranking,
etc.
This charger can be used on any number of lead-acid, nickel-cadmium, or nickel-iron cells as long as
the desired float and/or equalize voltages are within the range of the charger.
3. INSTALLATION
a. Location: Select a clean, dry location for the charger. It may be located in the battery room, but not
over the battery, and must be mounted upright. The openings for ventilation in the top, bottom and sides of
the cabinet should not be obstructed, as they provide convection cooling and ventilation. Ambient
temperatures between 32 Deg. F. and 122 Deg. F., and elevations up to 3,300 feet above sea level, will not
affect the performance of the charger. Operation at higher temperatures, or at higher elevations, is possible
if the ampere output is derated in accordance with published information, and if the charger is custom
ordered for these operating ambient conditions.
b. Wire Sizes AC: Wire sizes for the AC wiring may be selected by consulting the data on the
nameplate for input amperage. Local electrical or NEMA standards should dictate appropriate wire size.
Most codes specify that the AC wiring size must match the current rating of the input circuit breaker or
fuses.

2
c. Wire Sizes DC: The size of the charger leads should be selected to (a) carry the charger (ampere)
current rating, and also (b) provide less than 0.5 volt total drop at rated current in the loop or leads
between the charger and battery terminals. Choose the larger wire size that meets conditions (a) and (b).
Do not undersize. It is good practice to keep the DC leads as short as possible and to keep them together as
a pair to obtain low inductance. Likewise, it is good practice to avoid sharp bends and to run both DC
leads together if run in conduit.
d. Input Power: These chargers are nominal 120V, 208V, 220V, 240V (50/60 HZ) or 480V (60 Hz)
AC single phase. If the AC input data as supplied with the charger does not agree with the AC supply
voltage at the installation site, do not connect the charger to the AC line. The AC voltage must be within +
or -10% of the rated input voltage of the charger. If not, consult your power company or the battery
charger manufacturer.
4. PLACING CHARGER IN SERVICE
a. With the AC and DC breakers OFF and the system in float mode, install the charger making AC and
DC connections, as described in Section II, 3, and in accord with local regulations as they apply.
b. After connecting the lead from the positive (+) battery terminal to the positive (+) terminal on the
charger and the lead from the negative (-) battery terminal to the (-) terminal on the charger, observe the
voltmeter. It should read the correct polarity and be approximately the battery open circuit voltage (this is
2.0 volts per cell for lead-acid batteries and 1.2 volts per cell for nickel cadmium batteries). For example, a
60-cell lead-acid battery should read about 2 x 60 cells = 120 volts. This is a check that all cells are in a
true series (none connected in reverse) and all connections are tight. The open circuit voltage should be
about 8 to 10% below the rated float voltage.
c. The charger can now be energized by first closing the DC breaker to supply voltage for the control
circuits, then closing the AC breaker. Set the charger to “float”. The AC power ON pilot light should light,
and the ammeter should indicate charger output current. It is to be expected that the meter may show up to
110% current rating of the charger; the 110% being the factory setting of the current limit control.
d. The factory preset float voltage adjustment is shown on page ii and when this value is reached, the
charger ammeter should show a slow decrease in current, eventually down to a stabilized value. Please
note that whenever a charger is in a current limit condition, the output voltage is automatically reduced to
a value below the set float or equalize voltage. The voltage will not increase to normal value until the
battery’s state of charge increases, causing the charger current to decrease to a value equal to or less than
the rated current.
e. The factory adjustment of the equalizing charge voltage is also shown on page ii and assuming this
is as desired, the Float/Equalize switch may be switched to “Equalize”, to check the charger performance
at this voltage value. If a manual Equalize Timer (option) has been included, turn it clockwise to activate
the equalize charger mode. The charger ammeter may again go up to current limit until the equalizing
charger voltage is reached. The length of time required to reach this level depends on the state of charge of
the battery, and the ampere rating of the charger versus the battery rating.
f. With the charger operating at the desired float and equalizing voltage values, the system can be
considered installed and ready for service.

3
5. ADJUSTMENTS OF FLOAT & EQUALIZING CHARGE (also see Section IV, 1)
a. Each adjustment is made by means of a potentiometer with a slotted shaft for a screwdriver. The
potentiometers are front-panel mounted and appropriately marked. A lock nut on each potentiometer is
provided and should be tightened after the proper adjustment is completed. This prevents any accidental
misadjustments of the settings. The voltage response may be slow if a rise in voltage adjustment is desired;
because the battery state of charger and connected load must be considered. Turning the shaft clockwise
will raise the voltage, and turning counter-clockwise will lower the voltage.
b. Since accuracy of measurement is important when setting float and equalizing voltages, a precision
portable voltohmmeter with as leas one-percent accuracy is recommended for these DC measurements. A
conventional voltohmmeter or analyzer such as the Simpson Model 260 is also satisfactory, but is not as
accurate.
c. Any setting of the float voltage or equalizing charger voltage should not be considered final until the
ammeter shows less than charger rated current, and voltage does not change after several hours of
operation.
6. MANUAL EQUALIZE TIMER (OPTIONAL)
a. This timer is provided to obtain a charge up to 72 hours, at a slightly higher value than the ordinary
float voltage. The timer may be used for recharging older batteries, or for a freshening charge on new
batteries. For a detailed explanation of operation see Section V (Customer Options).
7. MAINTENANCE
a. This charger is designed to require a minimum of maintenance. There are no rotating parts except in
the optional timer and all components have a nominally indefinite life with no expected aging effect. It
should be kept clean, dry and checked periodically to make sure all connections are tight. If necessary, dry
air may be used to blow dust out of the interior. In the event of any irregular operation, examine, and
tighten if necessary, all internal and external connections and check circuits for continuity (see schematic
diagram on page 28). If the difficulty cannot be remedied, contact the manufacturer.
8. NORMAL PERFORMANCE
a. Assuming that the charger has been operating in the float position, an indication of normal
performance can be obtained by setting the FLOAT/EQUALIZE switch in the equalize position (turn timer
off zero). Increased charge current will show on charger ammeter until the battery reaches the equalize
voltage. At this point the current should slowly decrease.
b. If the charger has been operating in the equalize voltage position, turn SW1 to FLOAT (turn the
timer manually to zero). The charger will indicate zero or little output current until the float voltage is
reached. At this point, the current should increase slowly to the system load value, (the battery is now
“floating” across the line with approximately equal input and output currents).
c. When operating normally, the current limit control will limit the maximum charger output current to
approximately 110 percent of the rated charge current. In case of a high DC current demand, the current
limit control will keep the charger output within safe values without tripping the DC circuit breaker or the
AC breaker.

4
9. DESCRIPTION OF OPERATION
a. There are four major sections of the SCR single-phase charger which work together to produce
stable, regulated, filtered output. The functions of these four sections may be described as follows.
1. The Power Transformer T1. This section includes T1 and its associated input protection. Its
purpose is basically to supply an AC voltage of the proper magnitude and capacity to the rectifier section.
It also supplies various other voltages used by the control unit and accessories. It is connected to an AC
source by means of a circuit breaker.
2. The Rectifier Section. This section consists mainly of the voltage regulating silicon controlled
rectifiers and the power rectifier diodes. It accepts the AC voltage from the transformer, rectifies this
voltage to DC, and controls the voltage’s magnitude so that the charger output is regulated at all times.
The firing angle of the SCR’s is controlled by the action of the control module. Both the SCR’s and the
diodes are protected from AC and DC surge voltages by means of the metal-oxide varistor surge
suppressors.
3. The Control Module. This printed circuit board generates the single-phase phase-fired gate
signals that turn on the SCR diodes in response to the charging requirements of the battery load. The
output voltage of the charger is monitored by the voltage feedback circuit and advances or retards the
phase angle of the trigger pulses so that the output voltage is maintained essentially constant. This is
accomplished by comparing a small portion of the output voltage to a stable voltage reference and creating
an error signal proportional to the differential voltage. This error signal is then used to alter the phase
angle of the SCR gate trigger pulses in order to correct the output voltage. The load current is also
monitored by the circuit so that when its value exceeds an arbitrary value (110% rated current) the system
is “phased back” to limit the output current to no more than 110% of its rated value.
4. The Filter Section
(a). Depending on the application, the charger may be unfiltered. In this case, one filter choke,
L1, is utilized not for filtering but for phase correction of the highly leading current-voltage condition
created by the batteries during the charging pulses. The batteries represent a very large capacitor in shunt
with a resistive load. This creates out-of-phase current problems for the SCR diodes causing non-uniform
triggering problems particularly at low load currents. The single filter choke corrects this condition and
also aids the ratio of average current to RMS current flowing in the circuit.
(b). For filtered units, the objective is to remove the charging ripple at the battery terminals. To
accomplish this a "T" or "double-L" section filter consisting of inductors L1 and L2 and capacitors C1 and
C2 are used. C1 and C2 may consist of one or more individual capacitors. The degree of filtering required
dictates whether the "T" or "double-L" configuration is used. The "double-L" section filter is normally
used to reduce the ripple to 0.06% of nominal output voltage when the charger is operated as a filtered
eliminator.
SECTION III
CAUTION: Before trouble shooting, always isolate and deenergize the charger by opening the AC circuit
breaker, CB1 and the DC circuit breaker, CB2. This avoids the possibility of high short circuit current
damaging the charger, tools, test equipment, or injuring personnel. Note —Circuit breaker terminals and
terminal boards TB1, TB2, TB3, TB5 and TB15 have dangerous voltage across them even when breakers
are open. After isolating charger, check that the voltage across filter capacitors is zero, because once
charged they will take several minutes to discharge if bleeder resistor R1 is open. If CB2 is not provided,
remove the DC fuses F1 and F2 in order to isolate the charger from the battery. AFTER LOCATING THE
CHARGER PROBLEM, ALWAYS DE-ENERGIZE ALL AC AND DC CHARGER INPUTS AT THE
POWER SOURCE BEFORE SERVICING.

5
1. TROUBLE SHOOTING PROCEDURE
a. When a charger is not operating properly, the cause must be determined by checking various
components until the fault is located.
b. The major components are not checked in the order as listed in Section II, 9, since a charger may
exhibit a number of difficulties, each with different symptoms. In many cases, failure of one component
may cause another component or part to fail. Therefore, the following paragraphs treat major components,
functional circuits and parts individually (or by symptom). Together with serviceability measurements and
tests, the faulty part or component should be located.
c. Most of the following checks can be performed with an oscilloscope, a voltohmmeter (similar to a
Simpson Model 260) and an SCR tester.
d. Consult the trouble-shooting tabulation in Table A on page 27. When using the table, first locate the
fault symptom observed (in the left hand column) then follow the sequence for checking components in
the numerical order listed (1, 2, 3 etc.) for that particular symptom. Follow this check sequence until the
trouble is located. After correcting the trouble, check the charger for normal performance as described in
Section II, 8.
e. In addition to those symptoms listed in Table A, the following procedure should be followed:
For any condition
•Check voltage of the AC supply to insure that it is within 10% of the value of the specified input voltage.
•Examine charger for any evident loose or improper connections, particularly at the control unit, transformer
T1, input and output terminal board.
•Check continuity of battery circuit by comparing voltage at charger terminals with total of cell voltages.
•Check accuracy of voltmeter and ammeter on the charger.
2. TESTING OF COMPONENTS
a. Power Transformer, T1
1. With the AC and DC circuit breakers open or OFF, open the cabinet and carefully check the line
voltage across line terminals on TB1, terminals L1 to L2. Refer to Section III, 2, b, 1 if no AC voltage is
indicated. Check the wiring connections to ascertain that unit has the proper primary tap connections for
the line voltage indicated. Turn on the AC circuit breaker, CB1. Check that the voltage at the primary is
the same as that of the line. (If not, CB1 or wiring between it and T1 is open.) In this case proceed with
checks under Section III, 2, c, 1.
2. Check AC secondary voltage on T1 (see Table B below for expected voltage values). If
secondary voltages are much less than indicated, then either T1 is at fault or the power regulating devices
SCR1 or SCR2 are faulty.

6
TABLE B
SECONDARY VOLTAGE OF TRANSFORMER T1
(USE AC VOLTMETER)
Expected Voltages (AC) Leads or Locations
Approximately 2 times float
voltage, see page ii X1 to X5
120V AC Y1 to Y2
NOTE: The "X" of Table B voltages should be measured as they terminate on the full-wave bridge
components. All other voltages may be measured on the terminal strip on top of T1. Where power rectifier
fuses are employed in the larger power chargers (see custom diagrams and parts list), these fuses should
also be checked, and replaced if unserviceable.
b. External Circuit Wiring
1. When no line voltage exists between terminals L1 and L2 of TB1 check the AC line back to
source.
2. With no output, or a low output, the external DC wiring may be at fault. Check the wiring
between charger and battery to see that it is properly installed. Make certain that terminals are tight and
clean, and that the DC wiring is free from grounds. The total operating voltage drop in the loop or leads
between the charger and battery terminals should never exceed 0.5 volt (at rated charge current), and
preferably should be kept considerably below this limit by using a sufficiently large wire size.
c. Circuit Breakers
1. AC Circuit Breaker, CB1: When an AC voltmeter of suitable range is connected between leads
L1-L2 and indicates line voltage, but does not indicate when connected to the output terminals of CB1
when closed, the circuit breaker is probably defective. Deenergize the AC supply to the charger and
remove the leads to the circuit breaker. Use a voltohmmeter to check for continuity between the circuit
breaker terminals with breaker manually closed. Zero resistance should be indicated if the unit is
operative. If unit checks OK, check performance by measuring the AC voltage drop across each pole of the
breaker. This voltage should be under 0.1 volt when the load current is normal. If a higher voltage drop is
found, replace the breaker.
2. DC Circuit Breaker, CB2: When the DC circuit breaker is suspected of being inoperative or at
fault, a similar test to that made for the AC breaker will determine the operating condition of the breaker.
3. If the polarity protection diode, CR1, is shorted, the battery will discharge into CR1 which will
trip the DC circuit breaker, CB2. Check CR1 with an ohmmeter (both polarities) for a shorted condition
and replace if required.
d. Rectifier Diodes, SCR1, SCR2 (also see Section III, 2, f)

7
1. These diodes are a part of an SCR-diode module(s) in which the SCR's and diodes are contained
in a module(s) mounted by an electrically insulated heat sink plate. Three connections (plus one SCR gate
terminal) are available for checking. The diode portions should be checked by disconnecting one terminal
and measuring their forward and reverse resistance in either of two ways. In using an ohmmeter, use the R
x 1 scale for the forward resistance and this should show approximately 5 to 10 ohms. The reverse
resistance should be up in the thousands of ohms (probably 50,000 or more) measured with a higher scale
of the meter. The diodes may also be checked by connecting them in series with a 6 or 12 volt lamp across
a DC source of the same voltage. The lamp must be one which requires at least one-quarter ampere. The
lamp should light with nearly full brilliance with current flowing in the forward direction and not at all in
reverse. If it lights in both directions, the diode is shorted. If in neither direction, the diode is open.
2. Note that semiconductors usually short in pairs in bridge circuits, seldom as single units, and it
is rare that all four semiconductors in a bridge are found defective. When diodes fail it usually is because
of surge voltages, therefore, surge suppressors SS1 and SS2 should also be checked to determine that they
are operative (refer to Section III, 2, e).
e. Surge Suppressors, SS1, SS2
1. The metal-oxide varistor (MOV) type of surge suppressor is used throughout these battery
chargers instead of the older selenium type. This is because of personnel safety. When a selenium device
fails and arcs or burns, very toxic selenium fumes are given off which are very poisonous, if inhaled. The
MOV-type have a much sharper limiting “knee” characteristic and perform a better protection function. If
an MOV surge suppressor fails during a high energy transient, it may explode. This is an obvious failure
and the part must be replaced.
2. If the suppressor is shorted, an ohmmeter check will indicate continuity. When the suppressor
shows an infinite resistance in both directions measured with it disconnected from the charger and has a
normal appearance it can be presumed to be in good operating condition.
f. SCR Diodes, SCR1, SCR2 (also see Section III, 2, d)
1. These devices are part of the SCR-diode module(s) described in Section III, 2, d above. Power
regulating devices SCR1 and SCR2 are silicon controlled rectifiers, which cannot be checked using the
same method as used with rectifier diodes by forward and reverse resistance checks, since the SCR will
always show a high resistance until triggered.
2. The operation of the SCR can be checked with an oscilloscope. The gate firing voltage signal is
produced by the control module, A1 Assembly. The oscilloscope should be GROUND ISOLATED for
these tests. This is normally done by using a line isolation transformer in which the secondary that powers
the oscilloscope is UNGROUNDED. Alternatively a battery powered portable oscilloscope can be used.
The gate signal may be checked on the control module (see Section III, 2, g) or where the twisted-pair
trigger leads terminate on the SCR-diode module. The same signal should appear at both points. Absence
of the signal indicates that the control module is defective, not the SCR. (See Section III, 2, g).
3. If the charger AC input breaker trips immediately, and a shorted SCR is suspected, a simple
check with an ohmmeter can be made. Turn off CB1 and CB2. Connect to the anode and to the cathode
and adjust to the direct reading scale of the ohmmeter. If a low resistance is observed, reverse the leads
and again check the resistance. If this reading is also low, the SCR is shorted and should be replaced.

8
4. An SCR can also be checked for operation with a Simpson Model 260 voltohmmeter. With the
black lead in common and red lead in +, put polarity switch to + DC. Connect the red lead to the anode
and the black lead to the cathode. The meter should now indicate high resistance above 50,000 ohms
(when on the R x 10,000 scale). With the leads connected as above, set the function switch to R x 1 and
touch the gate to the anode. This should fire the SCR and give a reading of approximately 5-20 ohms. This
shows the SCR has been turned on. On very small SCR’s this reading will hold after removing the gate
lead. This is latched-on and can be unlatched by opening the cathode lead. Larger SCR’s will not stay on
with the current available with Simpson meter. The Simpson may not have enough current to gate or turn
on extremely large SCR’s (400 amp and up).
5. If the charger output is too high, unplug the control module and turn on the charger. With no
gate signals the charger should have zero output. If there is still current output, one or both SCR’s are
defective.
6. The above checks can be used to confirm that a suspected SCR is indeed bad. However,
occasionally an SCR might check OK in all these tests and still break down or fail in the charger circuit
during normal operation. Any SCR’s suspected should be replaced.
g. Control Module, A1 (PCB Assembly)
One preliminary note that should be kept in mind: The action of the overall feedback circuit
controls the battery charger output voltage so that the feedback voltage from the slider of potentiometer,
R3, “FLOAT ADJ.”, to the control module board matches the 6.4 volt reference voltage on the module.
Measure this voltage and if it is not approximately 6.4 volts the feedback circuit or related circuits are not
functioning. Proceed as follows using the GROUND ISOLATED oscilloscope described in Section III, 2,
f, 2 above. Make the following tests in the order shown.
1. If the gate signals were not checked as described in Section III, 2, f, 2 do so at this time. If one or
more of the gate signals are absent when attempting to operate the charger in a normal manner, make the
following checks. (Refer to FIGURE 1 on page 29 for component layout and test point locations on the
trigger board. See schematic on page 30 for related circuit diagram.)
2. Check DC voltages at test points A (+ 10 volts) and B (-10 volts), referred to board ground,
(GND). If either or both voltages are missing, check fuse F1, transformer T1, and diodes CR1 through
CR4 on the PCB for malfunction. If ok, proceed as follows.
3. The following waveform tests must be made using the oscilloscope set with vertical sensitivity
set at 2V/CM and the horizontal time base set at 5MS/CM. Compare the waveforms observed with those
shown in FIGURE 2 on page 31 for the various test points indicated.
4. Check waveform at test point C and compare with FIGURE 2. If improper waveform check
CR12 and CR13. Check amplified inverted waveform at test point D. If not present, replace IC2.
5. Check ramp pattern at test point E. If not proper, replace Q1 only with its own type, Motorola
MPSA55. Do not substitute.
6. Check the ramp with floating DC reference at test point F. If not present, replace IC2.
7. Check the short pulse at point G. If not present, check unijunction transistor Q3.
8. Check waveform at point H. Note that at both points G and H, there may be multiple pulses
instead of only one pulse per 8.33ms. period. This is normal particularly if the unit is calling for maximum
output voltage. If no pulse waveform is present replace transistor Q2.
9. Check the battery charger rectified waveform by connecting the oscilloscope across the bleeder
resistor, R1, and readjusting the input sensitivity to 20V/CM. If the unit is turned “half-on”, the waveform
will look approximately like the waveform of I of FIGURE 2.

9
h. Current Sensing Resistor
1. In light current chargers, the current sensing signal is taken directly across the DC ammeter. In
chargers with 50 Amp or higher output current, the sensing resistor is a meter shunt which also serves as
the shunt for the panel ammeter. Use a portable precision digital voltmeter and measure the voltage drop
across the current sensing resistor. With a rated current output indicated on the panel ammeter, a nominal
voltage drop of approximately 30mV (in proportion to rated current) should be observed. If the voltage
drop is higher or lower than the nominal indication, replace the ammeter or shunt and recheck the voltage
drop.
i. DC Voltmeter, M2
1. The DC voltmeter is of the 2 percent accuracy type. It is connected across the charger output to
the battery and should indicate regardless of whether or not the charger is operating or the DC breaker is
ON. If it does not, use a precision voltmeter of the 1% accuracy type connected across the meter terminals.
An indication on the test meter will show that the panel meter is open. Check the wiring for an open
circuit, or replace meter if circuit wiring is complete.
2. A shorted voltmeter will show no indication. Battery current through a shorted meter will cause
a visible indication such as smoke from burning wire insulation. Disconnect the charger from the battery
and AC source and replace the meter and damaged wiring.
3. If the meter calibration is in doubt, checking against a precision meter will determine if the panel
voltmeter is off calibration more than two percent.
j. DC Ammeter, M1
1. The charger DC ammeter is connected in series between the charger output and battery. If open
it will indicate zero, or if shorted, it will also indicate zero. First be certain the connections are tight. If still
no indication, turn CB1 and CB2 breakers to OFF, disconnect the charger ammeter (and/or shunt) and
substitute a precision ammeter of suitable range. Be certain to make solid connections; clip contacts may
not carry sufficient current, or may make poor contact and cause the reading to be inaccurate.
2. A reverse-scale indication of the meter indicates the charger is inoperative or internally shorted,
and that the battery is discharging through the rectifier, or that the meter leads have been reversed. Turn
CB1 and CB2 to OFF and check wiring and meter connections. Then check meter operation, using a 1 ½-
volt D-cell as the power source. Momentarily touch D-cell terminals (with proper polarity) to meter
terminals and observe meter deflection.
k. Filter Capacitors, C1 & C2 (Filtered Chargers Only)
NOTE: Capacitors C1 and C2 may consist of one or more parallel connected capacitor units as
required by the filtering requirements. C2 normally is used only in chargers with the filtered eliminator
option.
CAUTION: The filter capacitor is on the charger side of the blocking diode, CR2, and is NOT charged
by the battery when CB2 is turned ON. When the charger is turned OFF (CB1 opened) the capacitor will
hold a charge until discharged by bleeder resistor, R1. Capacitors C1 and C2 should always be discharged
before servicing in the event the R1 has opened and no longer serves as a bleeder.

10
1. Before attempting to check the output ripple, it should be determined that in all other respects
the charger is operating normally. Having determined this, the ripple may be checked as follows. Connect
a sensitive AC voltmeter (digital type preferred) to the battery terminals and measure the AC ripple
voltage. If it measures more than 30 millivolts RMS check the following:
(a). That the battery connected to the output terminals of the charger has an 8-hour ampere-hour
rating of at least four times the rated capacity in amperes of the charger.
(b). The ripple is measured at the terminals of the battery.
(c). Check capacitors C1 and C2 as follows: Switch the voltohmmeter to the R x 100 scale and
connect the red lead to the capacitor plus terminal (marked by a red dot or plus sign) and the black lead to
the negative terminal. The meter should initially swing up scale toward zero ohms, then come back as the
capacitor charges. A reading of zero ohms indicates a shorted capacitor while no initial swing means an
open capacitor. Either an open or shorted capacitor should be replaced.
l. Internal Wiring
1. Check internal wiring for obvious mechanical faults or wear. Follow the schematic diagram on
page 28 and check continuity with an ohmmeter to determine open connections. Check wiring against
ground also, and remove any grounds.
SECTION IV
SYSTEM ADJUSTMENTS
1. VOLTAGE ADJUSTMENTS AND RESPONSE
When abnormal output voltage exists (or no output current is present) and the previous checks in Table
A on page 27 “VOLTAGE ADJ. INEFFECTIVE” have been made without locating the fault, switch CB1
to OFF. Switch CB2 to OFF or disconnect the battery and proceed as follows:
Check the battery with a portable voltmeter of one percent accuracy to insure that it is not higher than
the rated float voltage. For proper operation, the open circuit voltage of the battery must be slightly lower
than the rated float voltage. If the battery voltage is higher than the float voltage range, check the number
and type of cells connected to the charger making certain the proper number and type of cells are not
exceeded. Close CB2 breaker or connect charger to battery. Close CB1 breaker. If battery voltage is now
within the float voltage range or is slightly lower and some output current exists, proceed with Section IV,
1, a, 2 below.
If the battery voltage is slightly lower or within the float voltage range, switch the charger to the
equalize mode. If still no output appears, or the potentiometer, R5, does not produce a rise from the
previous value, turn equalize charge control fully clockwise, and if still no voltage rise is obtained or no
output appears, proceed again with the check sequence in Table A trouble-shooting chart. If the voltage
increased or output was obtained when the charger switched, to evaluate proceed with the voltage
adjustments.

11
a. Float Adjustment
1. Since the charger must be operable for this adjustment, preceding checks in Section IV, 1 above
must indicate a serviceable charger. Set SW1 to “FLOAT”. Use a portable voltmeter of one percent
accuracy. Connect the battery supply leads to the battery and close DC (battery) circuit breaker, CB2. Set
AC circuit breaker CB1 to ON.
2. Since the EQUALIZE and FLOAT potentiometer control settings interact with each other, it is
always necessary to adjust the FLOAT control first and then the EQUALIZE control afterward. Never
finalize a voltage adjustment with the charger output in excess of 100% rated output current.
3. Turn the control clockwise, watching the response on the voltmeter. Clockwise rotation should
cause the charger output current to increase rapidly, while the voltage should rise slowly. The rate of
voltage rise depends upon whether the battery is fully charged, the size of any connected load, and the size
of the charger versus the size of the battery. After getting several volts response in battery voltage rise,
turn the FLOAT control counterclockwise. This should result in a rapid drop in charger output current and
eventually in a slow decrease in battery voltage. Now adjust the voltage for the desired float setting and
tighten the locknut on the potentiometer.
b. Equalize Adjustment
1. Since the equalize adjustment will not affect the float voltage adjustment and requires a higher
voltage it should always be made after the float voltage is determined. Use a portable voltmeter of one
percent accuracy as in the float adjustment. Set SW1 to “EQUALIZE”. Close DC (battery) circuit breaker.
Set AC circuit breaker CB1 to ON.
2. In attempting to set the equalize voltage setting, one thing must be kept in mind. It will be
impossible to set the equalize voltage if the batteries are in a discharged condition. If fact, they must be at
near full-charge. This is to prevent the charger from going into a current limit condition. Current limit
reduces the charging voltage and no matter if the EQUALIZE potentiometer is increased to a full-
clockwise position, the charger voltage will not increase.
3. Therefore, it is suggested that the batteries be placed on equalize charge for several hours so that
the charger is no longer in current limit. This should be observed using the portable 1% accuracy voltmeter
and the charger panel ammeter. When the charging current falls below the 100% rated value of charger
current, observe the voltage and set carefully for the desired equalize voltage. If, upon readjustment, the
current again goes into current limit wait for the batteries to continue their charge cycle. Continue this
adjustment procedure until the desired voltage is reached and the current is less than rated current. When
the final setting is determined, tighten the lock nut on the EQUALIZE potentiometer.
2. CURRENT LIMIT RESPONSE AND ADJUSTMENT
a. Make certain the charger leads are connected to the battery and that the panel voltmeter indicates the
proper polarity. Switch the battery DC circuit breaker CB2 to ON and AC line circuit breaker CB1 to ON.
The indicating light, DS1, should illuminate, indicating power has been applied. With the charger in float
mode a float voltage charge should be indicated on the panel voltmeter and the ammeter should show
either a charge current, or practically none at all, depending on the state of battery charge.

12
1. If the batteries are in a discharged condition, switching to the equalize mode will cause the
charger to automatically go into a current limit condition. If, however, the batteries are fully charged they
probably will not draw current in the current limit range. In order to cause this condition, it will be
necessary to connect additional load to the battery charger or battery bank. This can be resistive elements
or turning on the normal load of the installation. When current limiting is encountered, observe that the
charger voltage will be reduced below its set value by the current limit feedback signal. Observe that as the
current limit condition continues, the voltage will slowly increase as the batteries take on a charge.
Eventually the current will begin to decrease below the current limit value and continue to decrease to a
value less than 100% of rated output current. As the current decreases below 100% of rated output current,
the voltage will become constant at the equalize value and remain so. To check the system response
proceed with Section IV, 2, a, 2 below.
2. Now turn AC breaker OFF to simulate line voltage failure. Charging current should return to
zero (panel ammeter), and the voltage should reduce slightly. Place a load on the battery and discharge it
heavily for a short period of time until the voltmeter drops to float value or slightly lower. Return AC
breaker to ON and observe that charge ammeter again reads 110% of charge rate and voltage is less than
the equalizing level. If current is greater than, or less than 110 percent of rated charge, open the cabinet
and locate the CURRENT LIMIT potentiometer on the control trigger board (A1 Assy.). This is R11 on
component layout page 29 and schematic page 30. Adjust this control for 110% charge current. Repeat AC
circuit breaker ON-OFF sequence above. If charge rate is still 110% rated value for which it was set, close
the cabinet. Restore the charger to float mode.
b. If all of the above adjustments were attempted and a high current persists, the current limit circuit on
the control trigger board or the ammeter or shunt used for current sense may be defective. The
interconnecting wiring may also be faulty. Make the following checks to isolate the fault.
1. Turn the current limit control (R11 on control trigger board) to determine if it has any effect on
the high output current reading. If it does, make the adjustment for 110% rated current for a current limit
setting as described in paragraph IV, 2, a, 2 above.
2. If no effect is noted, IC1 on the control trigger board may be defective, if so replace.
3. Check the voltage generated across the ammeter (or meter shunt) to determine that sufficient
voltage is available at rated current to activate the current-limit feedback amplifier. See Section III, 2, h.
Using a sensitive DC voltmeter measure across the ammeter and from pin #1 to pin #10 (signal ground) on
the plug of the trigger control board, A1 assembly. If the sense voltage is not present at the control trigger
board check the wiring. If the wiring is satisfactory, proceed with the check sequence listed in Table A
trouble shooting chart on page 27.
SECTION V
CUSTOMER OPTIONS
The following pages describe customer options included in battery chargers. The text describes the basic
operational philosophy and briefly the theory of operation. The block diagrams or schematics are shown at
the end of Section VII in numerical order of the “EJ” specification number.

13
1. GROUND DETECTION CIRCUITS
Purpose: The purpose of a ground detector circuit is to indicate to the user when either the positive (+)
or negative (—) output terminal of the battery charger (or its connected load) is grounded. This is
important for many applications where a full floating system is required for operation or safety reasons.
There are several methods of indicating a grounded output terminal. These will be outlined below with an
explanation of how each works.
Description:
a. TWO LAMP SYSTEM (EJ0088-XX): The most simple form of a ground detection system is the
two lamp method. This utilizes two lamps of voltage equal to the battery charger output voltage connected
from the positive terminal to ground and from negative terminal to ground. Under normal conditions, each
bulb will have half-voltage applied and glow dimly at quarter-brilliance. Upon a ground, the lamp
indicating the grounded terminal will glow at full brilliance. The other lamp will go out.
b. TWO LAMP SYSTEM WITH TEST SWITCH (EJ0089-XX): This is a variation of “a.”, above, so
that the two lamps are not continuously connected in the circuit. A double-pole, double-throw, momentary
center off switch is utilized. Activating the switch in one direction will connect the two lamps in series
across the battery with the center attached to chassis ground and perform as the two lamp system, EJ0088,
as described above. Activating the switch in the other direction serves to test the lamps.
c. SWITCHABLE DC VOLTMETER METHOD (EJ0094-XX): This method uses the existing panel
DC voltmeter and two double-throw switches to utilize the voltmeter in both functions. Switch SW8
establishes the meter function (output voltage or ground detection) and SW9 switches the voltmeter
between (+) or (—) terminal to chassis ground reversing the meter polarity to maintain up-scale
indications. The voltmeter, used in the ground detection mode, will indicate the DC voltage potential
between the corresponding output terminal and chassis ground. For cases of partial grounds, the voltmeter
will indicate the difference of the terminal DC voltage and the voltage of the partial ground.
d. GROUND DETECTION ALARM RELAYS WITH OPTIONAL LIGHTS (EJ0086-XX): This
method utilizes two DC relays which monitor the (+) and (—) terminal voltage to chassis ground and will
energize if the opposite polarity terminal is grounded. To insure that the relays will not energize on half-
voltage, when there is no ground present, series resistances are used to reduce the relay pull-in sensitivity.
However, once pulled in by a ground condition, the relays will not drop out when the ground is removed
because the drop out voltage of a DC relay is always less than the pull-in voltage. As a result, a
momentary “RESET” switch must be activated to open the relays returning them to the “ready” condition.
The EJ0086 schematic shows the circuit diagram of this method. The panel lamps shown are a user option
that is available for front panel indication. The relay coil voltages, and series resistances will depend on
the output voltage of the battery charger.
2. AC POWER FAILURE ALARM RELAY (EJ0085-XX) WITH OPTIONAL LIGHT
Purpose: The purpose of this alarm is to notify the user that the AC input power to the battery charger
has been interrupted. A front panel lamp is optionally available for local indication. Relay contacts are
provided for remote monitoring.

14
Description: The principle of operation utilizes the normally closed contacts of an AC relay. The relay
is powered from the AC line at the primary of the power transformer T1. The relay, when energized, holds
the normally closed contacts open disabling the alarm indication. When the AC line fails or the AC circuit
breaker is opened for any reason, the alarm contacts will close activating the alarm indicator. EJ0085
shows the circuit with the optional panel indicator lamp and external relay connections for remote
indication. The indicator lamp must operate from the battery power since the AC line power is not
available in an alarm state. As a result, the indicator light operating voltage must match the battery DC
voltage or must utilize a series dropping resistor to compensate for the difference in voltage between the
battery and indicator lamp.
3. AC VOLTMETER AND AC AMMETER OPTIONS
Purpose: These options are to permit the user to monitor the input AC line voltage and line current to
the battery charger. This may be done for either single phase or three phase input power.
Description:
a. Single phase AC: EJ0095 and EJ0134 show the connections to the voltmeter and ammeter. The
ammeter is usually connected to the AC line via a current transformer if the line current is over 50
Amperes.
b. Three Phase AC: EJ0121 and EJ0135 show the connections utilizing a single voltmeter and single
ammeter to monitor the three phase-to-phase voltages and the three line currents. This is accomplished by
using a two-pole, three position switch (SW5) to switch the voltmeter from phase-to-phase to check all
three input voltages. The ammeter switch (SW6) is a special switch that shorts all unused current
transformer secondaries, and upon changing switch position shorts the current transformer secondary in
use before transferring the ammeter to a new position. This prevents very high voltage arcs when the
secondary is open circuited. CAUTION: NEVER OPERATE A CURRENT TRANSFORMER
WITHOUT A SECONDARY LOAD OR SHORT CIRCUIT ACROSS THE SECONDARY
TERMINALS.
4. HIGH AND LOW DC VOLTAGE ALARM RELAYS (EJ0083-XX) WITH OPTIONAL LIGHT
Purpose: The HIGH/LOW Voltage Alarm (HLVA) provides alarm indication for the DC system in the
event of a malfunction of the battery charger or extended loss of AC power which causes the battery
voltage to drop to a dangerous level. Alarm indications are provided by relay contacts and optional front
panel lamps.
Description: The HLVA printed circuit board consists of two independent operational amplifier
circuits, one monitoring the battery voltage for a high voltage condition and the other monitoring for a low
voltage condition.
The board obtains its operating voltage (12VDC) from the battery terminals and if required, an
externally mounted dropping resistor (R57).
There are two potentiometers on the HLVA board (A2 PCB Assy.). Viewed from the component side
of the board, the potentiometer near the top-left of the board is the LOW voltage alarm (LVA) threshold
adjustment. The right-hand potentiometer at the top of the board is the HIGH voltage alarm (HVA)
threshold adjustment.