National Railway Supply ELC-24/10-M-D Service manual

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NATIONAL
RAILWAY
SUPPLY
Installing, Operating and
Service Instructions for the
ELC-24/10-M-D
Solid State Charger
MODEL ELC-24/10-M-D
BATTERY CHARGER
PLEASE SAVE THESE IMPORTANT SAFETY AND OPERATING INSTRUCTIONS
For correct operation of the equipment, it is important to read and be familiar
with this entire manual before installing and operating the charger.
DO NOT DISCARD THIS MANUAL AFTER READING.
LOOK FOR THIS SYMBOL TO POINT OUT SAFETY PRECAUTIONS. IT MEANS:
BECOME ALERT—YOUR SAFETY IS INVOLVED. IF YOU DO NOT FOLLOW THESE
SAFETY INSTRUCTIONS, INJURY OR PROPERTY DAMAGE CAN OCCUR.
1. IMPORTANT SAFETY INSTRUCTIONS
a. Before using the battery charger, read all
the instructions and caution markings on the
battery charger, the battery, and all of the
products using the battery.
b. Do not touch the uninsulated parts of the AC
input or the DC wires, the charger's binding
posts, or the battery terminals, as there is a
possibility of electrical shock.
c. Batteries produce hydrogen gas while
operating, which can explode if ignited.
Never smoke, use an open flame, or create
sparks in the vicinity of the battery. Ventilate
the area well when the battery is charging in
an enclosed area.
d. Batteries contain caustic material which may
cause burns. Do not get in eyes, on skin, or
clothing. If the gelled or liquid content of the
batteries contacts the skin or clothing, wash
the area thoroughly with water. In the case
of contact with the eyes, flush immediately
with clean water for 15 minutes and obtain
medical attention.
e. Only qualified personnel should program or
service this equipment.
f. De-energize all AC and DC power
connections before servicing this unit. If
injury does occur, apply standard treatment
for electrical shock and, if necessary,
consult with a physician.
g. The charger is not for outdoor use. Do not
expose the charger to rain or snow.
h. Do not operate the charger if it has received
a sharp blow, been dropped, or otherwise
damaged.
i. Do not disassemble the charger. Have the
charger examined by a NATIONAL
RAILWAY SUPPLY service agent. If the
charger is assembled incorrectly, damage to
the charger and the batteries or an electrical
shock may result.
2. DESCRIPTION
The NATIONAL RAILWAY SUPPLY charger, model
ELC-24/10-M-D, is a convection-cooled, solid state,
SCR regulated charger that provides either a
constant current or constant voltage output. The
charger can be set to charge batteries within a
voltage range of 20.0 to 35.0 volts for gel-cell, liquid
lead-acid, nickel cadmium, nickel iron, and starved
electrolytic batteries.
*38502*

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3. THEORY OF OPERATION
When the charger is connected to the desired AC
voltage source (115 or 230), the transformer creates
auxiliary voltages for the electronic control module.
The electronic control module controls and monitors
the charger so it will perform properly. The
transformer also supplies the power output used for
charging the batteries and provides electrical
isolation between the charger's output and the AC
source.
The charger's output current flows through a shunt
and is sensed by the electronic control module along
with the charger's output voltage. These values are
converted into drive pulses for the SCRs by the
control module. This pulsating charge current (a
pulse occurs each time an SCR is on) is then filtered
by a large capacitor and the batteries to provide a
smooth output.
The charger has an "IE" profile which is: (a) High
rate constant current, and (b) Constant voltage.
When the charger is first started, the SCRs will
conduct for a certain portion of the sinusoidal anode
voltage to provide the required charging current at
the low level of battery voltage. In this start region, a
constant current is applied to the battery. The SCR
conduction will then increase as the battery voltage
increases in order to provide a higher output voltage
while maintaining a constant charging current.
When the battery voltage reaches the float voltage,
the SCRs will start to decrease their output. This
causes the charger to automatically change from a
constant current charge region to a constant voltage
charge region. As the batteries become fully
charged, the output current decreases. A
continuous constant float voltage will be supplied to
the batteries to maintain their charge.
Another feature of the charger is temperature
compensation, which keeps the batteries from
getting under- or over-charged. TEMPERATURE
COMPENSATION ONLY OCCURS WHEN USING
A TEMPERATURE PROBE. The red LED on the
front of the charger will be off when using a
functional temperature probe. If the LED is on,
either a temperature probe is not being used, or the
temperature probe is working improperly.
Temperature compensation uses a temperature
reference of 77°F (25°C), a voltage reference of
2.23 volts (the voltage of a standard gel-cell battery
at 77°F), and a compensation value of 3.0 mV per
°F). The equivalent equation for the compensated
voltage is:
Vcomp = V – k (t - 77°F)
Where V is the voltage of the battery at 77°F, t is
the temperature in °F, and k = V (.003 / 2.23).
The control module has a temperature
compensation range between 32°F and 95°F ( 0°C
and 35°C) that does not allow charger voltage to
increase or decrease beyond the calculated values.
Example 1:
If a 27.2 volt battery is charging and the
temperature increases to 95°F, then the output
voltage decreases to 26.54 volts.
27.2 - .0366 (95°F - 77°F) = 26.54
Example 2:
If a 29.0 volt battery is charging and the
temperature increases to 95°F, then the output
voltage decreases to 28.3 volts.
29.0 - .039 (95°F - 77°F) = 28.3
Example 3:
If 27.2 volt batteries are charging and the
temperature decreases to 32°F, the output voltage
increases to 28.84 volts.
27.2 - .0366 (32°F - 77°F) = 28.84
4. RECEIVING AND INSTALLING THE
CHARGER
Proper installation of the charger is important in
order to achieve good charger performance and to
prevent damage to the charger and batteries. When
a charger is received, a check for possible in-transit
damage should be made. If any damage is found, it
should be reported as a claim to the carrier. To
permit free air flow for convention cooling, allow
three inches (3") minimum between the charger
sides and other equipment and four inches (4")
minimum on top of the charger.
WARNING: NEVER PLACE ANYTHING ON
TOP OF THE CHARGER WHILE OPERATING.
DAMAGE TO THE CHARGER OR BATTERIES
COULD OCCUR.
WARNING: THE CHARGER MUST BE SET
UP FOR THE PROPER USER SPECIFICATIONS
BEFORE STARTING THE INITIAL CHARGE.
5. AC ELECTRICAL SUPPLY
The charger must be connected to a single-phase,
50/60/100 Hertz AC power source, which can be
either 115 or 230 VAC depending on the charger
input voltage selection switch setting. Use an
appropriate size wire for the conditions and for the
AC amperage shown on the ratings information on
the charger. Quarter-inch (1/4") ring terminals are
required for proper connection to the AC input and

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ground binding posts (A.A.R.) located on the front of
the charger. Open the small door cover on the front
of the charger by pulling out on the push tabs.
Connect the AC power terminals on the two posts on
the right, as marked on the panel behind the posts.
Connect the AC ground to the terminal lug provided.
WARNING: FAILURE TO PROPERLY
CONNECT THE AC VOLTAGE CONDUCTORS
COULD CAUSE SERIOUS DAMAGE TO THE
CHARGER. BE SURE TO SET THE VOLTAGE
SELECTION SWITCHES ON THE FRONT OF THE
CHARGER TO THEIR PROPER POSITION.
WARNING: DO NOT OPERATE THE
CHARGER WITHOUT PROPER GROUNDING.
IMPROPER GROUNDING CAN RESULT IN THE
RISK OF AN ELECTRIC SHOCK.
6. DC OUTPUT
The DC output wires are connected on the two left-
most binding posts as marked on the panel behind
the posts (positive on the left and negative on the
right). The DC cables should have quarter-inch (¼")
ring terminals for connecting them to the binding
posts. Check to make sure the polarity of the DC
output wires are the same as those connected to the
battery. The charger will not operate in a reversed
polarity condition. WHEN CONNECTING THE DC
WIRES TO THE CHARGER WITH THE AC
POWER DISCONNECTED, A SPARK MAY
OCCUR. This is caused by the output capacitors
being charged by the batteries. If the DC polarity is
reversed, a circuit breaker will protect the charger
from internal damage. Correct the reversed wires
and push the circuit breaker button back in. Close
the door cover on the front of the charger after
tightening all of the binding post nuts.
WARNING: DO NOT TOUCH THE
CHARGER'S TERMINALS OR AN ELECTRICAL
SHOCK COULD OCCUR. A VOLTAGE IS
PRESENT ON THE DC TERMINALS EVEN AFTER
THE AC IS DISCONNECTED BECAUSE OF THE
ENERGY STORED IN THE CAPACITOR.
7. TEMPERATURE PROBE
The external temperature probe is an optional way
of extending battery life by using temperature
compensation. One end of the temperature probe
cable has a three-pin plug, which plugs into a
receptacle labeled TEMP PROBE on the front of the
charger. The other end of the cable has the
temperature sensor sealed in a terminal.
WARNING: IT IS IMPORTANT TO MOUNT
THE TEMPERATURE PROBE ON THE
BATTERIES FOR PROPER TEMPERATURE
COMPENSATION. IF THIS CANNOT BE DONE,
LOCATE THE PROBE AS LOW AS POSSIBLE IN
THE BUNGALOW OR CABINET.
Terminal-Type Probe
The terminal-type probe should be attached to the
negative (-) battery post near the center of the
battery pack. If the threaded stud is long enough
above the battery jumper nut, attach the probe with
another nut. Torque this nut to proper
specifications. If the stud is too short, the nut
holding the jumper wire will need to be removed.
Open or remove the load and charging circuits to the
batteries. Remove the nut holding the jumper and
add the probe, then torque the nut to the proper
specifications. Then close or connect the load and
charging circuits back to the batteries.
Securely fasten the temperature probe cable to
protect the probe from being torn from the
battery. Secure the probe's cable to a fixed object
to ensure the probe will not be pulled loose. Use a
cable tie mount on the battery or on the adjacent
battery, if necessary.
8. OPERATION
The battery charger is adjustable with the three
rotary switches on the front of the charger. The
switches (settable between 20.0 and 35.0)
determine the float voltage for the batteries. SET
THE FLOAT VOLTAGE TO THE BATTERY
MANUFACTURER'S SPECIFIED VOLTAGE FOR
77°F. The charger will then electronically charge the
batteries to the voltage specified on the switches.
To set the switches, use a small screwdriver and
turn the switch so that the arrowhead on the slot is
pointing to the desired number. Set the switches in
the following manner: If the desired battery voltage
is 27.2 volts, set the top switch to 2, the middle
switch to 7, and the bottom switch to 2 (see the
figure 8.1). This will provide you with the proper
charging voltage. BE SURE EACH SWITCH IS
SET ON A NUMBER AND NOT BETWEEN
NUMBERS. If a switch is set between numbers, the
output current will go to zero and the yellow charging
LED will flash.
The charger does not have a power switch. When
the AC power is applied to the charger, the DC
output will start and the yellow LED will be on. To
turn off the charger, disconnect the AC power
source.

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Figure 8.1
9. CURRENT MONITOR/ALARM
The ELC-24/10-M-D battery charger includes an
integrated current monitor/alarm that monitors the
output current of the charger. If the charger output
falls below the current limit setting, a green LED
indicator is turned off and a Form C, dry contact
alarm relay is actuated. The current limit
adjustment, LED, and relay terminals are accessible
on the front of the charger (see Figure 9.1).
Figure 9.1
Relay Terminal Remote Wiring
The OPEN, COMMON, and CLOSED relay contacts
have push-in type terminals for remote wiring. The
relay contacts are rated for 1A at 30 Vdc or 0.5A at
120 Vac. A small screwdriver (3/32 inch maximum
blade width) is required to insert or remove a wire
from a relay terminal.
WARNING: BE CAREFUL! IF AN
UNINSULATED METAL TOOL CONTACTS BOTH
THE GROUNDED CHARGER CASE AND A
RELAY TERMINAL PUSH-IN TAB, THIS WILL
CAUSE A POTENTIALLY DAMAGING AND/OR
DANGEROUS ELECTRICAL SHORT.
Current Monitor/Alarm Operation
Table 9.1 outlines the operation of the LED and
relay based on the status of the current monitor. All
relay contact states are with reference to the
terminal strip COMMON.
Current Monitor Status LED CLOSED
Relay Contact OPEN Relay Contact
Charger output exceeds the current limit setting On Closed Open
Charger output falls below the current limit setting
(and AC power is present at the charger) Off (after approx. 30
seconds)
Open
(after approx. 30
seconds)
Closed
(after approx. 30
seconds)
AC power is removed from the charger Off
(immediately) Open (immediately) Closed (immediately)
Table 9.1

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Current Limit Adjustment
The current limit adjustment should be set to a level
that is below the charger output when sourcing the
minimum DC load of the system and floating the fully
charged battery set. The current limit adjustment is
factory-set to approximately 400 mA (fully
clockwise), which should work for most applications.
If the minimum DC load of the system combined with
the battery float current is above approximately 500
mA, leaving the current limit adjustment at the
factory setting of 400 mA is recommended. If an
adjustment is required, it can be adjusted between
approximately 400 mA and 15 mA. Setting the
current limit adjustment below approximately 100
mA is not recommended due to internal charger DC
current that can still exist and be monitored if the
charger DC output is disconnected from the load
and battery set.
Adjustment Procedure
A small screwdriver (3/32 inch maximum blade
width) is required to change the current limit
adjustment.
With AC power applied to the charger input and the
charger DC output connected to the load and fully
charged battery set, monitor the charger output
current until it stops decreasing and levels off at the
minimum system current. Ensure that the current
limit adjustment is turned fully clockwise, which will
set the current limit at approximately 400 mA. If the
LED is on and the CLOSED relay contact is closed
when the current limit adjustment is turned fully
clockwise, leave it in that position. If the LED is off
and the CLOSED relay contact is open when the
current limit adjustment is turned fully clockwise, turn
it slowly counterclockwise until the LED turns on and
the CLOSED relay contact closes. Turn the current
limit adjustment approximately 1/8 of a turn
counterclockwise from this switching point. Remove
AC power from the charger to verify that the current
monitor/alarm is functioning. The LED should turn
off and the CLOSED relay contact should open.
Current Monitor Specifications
CURRENT MONITOR/ALARM RELAY CONTACT
RATINGS:
1A at 30 Vdc
0.5A at 120 Vac
TERMINAL CONNECTIONS:
20 – 16 AWG wire, stripe length of .312 - .359
inches (8 – 9 mm)
10. MAINTENANCE
The battery charger requires minimal maintenance.
It should be kept clean and all connections are to be
periodically tightened. BE SURE THE CHASSIS IS
SECURELY GROUNDED. If any problem cannot
be resolved, consult the nearest NRS service agent
1-800-357-3572.
11. SERVICING
If the battery charger operates improperly, follow the
steps below.
a. Begin by checking the voltage switches to
verify their settings against the
specifications of the batteries.
b. Check the AC voltage selection switch for
the proper setting.
c. Check the fuses to make sure they have not
blown.
d. Check the circuit breaker to see if it has
opened and push it in to reset it, if
necessary.
e. Check the polarity between DC output and
the battery and make sure their connections
are tight.
f. Remove the small cover on the front of the
charger and make sure all of the binding
posts nuts are tight.
g. If the steps above do not solve the problem,
contact your local NRS service agent
1-800-357-3572.
12. CHARGER SPECIFICATIONS
AC INPUT VOLTAGE:
115 Vac (108-128) or 230 Vac (216-256)
AC INPUT CURRENT:
7 amps for 115 Vac (full power)
3.5 amps for 230 Vac (full power)
AC INPUT FREQUENCY:
50/60/100 Hertz (single phase)
AC LINE REGULATION:
DC output at 27.2 volts (2.27 volts/cell for 12
cells) @ 10 amps
26% for 50 or 60 Hertz 115 Vac
20% for 100 Hertz 115 Vac
AC FUSES:
MDA 5

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DC OUTPUT:
Voltage range 20.0 – 35.0 + 1% 50/60/100
Hz
Current Maximum 10 + 0.6 amps
TEMPERATURE COMPENSATION:
3mV per °F per cell
WEIGHT, NET:
30 lbs.
13. PARTS LIST
The following is a list of parts found in the NRS model ELC-24/10-M-D. When replacing a part, USE ONLY
ORIGINAL FACTORY REPLACEMENT PARTS of the correct size and rating.
PART NO. QTY. DESCRIPTION
38641S 1 CASE ASSEMBLY MODEL 27760
38018S 1 CONTROL MODULE (W/ ELECTRONIC BOARD)
38501S 1 CONTROL CABLE
38508S 1 CURRENT MODULE
38308S 1 CURRENT MONITOR MODULE MOUNT
05322S 2 FUSEHOLDER ASSEMBLY
15554S 2 FUSE, 5 AMP
38027S 1 CIRCUIT BREAKER ASSEMBLY
31177S 1 AC SWITCH ASSEMBLY
27317S 1 AMMETER, 25 AMP
14197S 4 BUSHING, 1"
29741S 1 TEMPERATURE TRANSDUCER, 10' (W/ TERMINAL)
29742S 1 TEMPERATURE TRANSDUCER, 30' (W/ TERMINAL)
37941S 1 HEATSINK ASSEMBLY, W/ SCR
38028S 1 CAP ASSEMBLY, W/ DIODE ASSEMBLY
31171S 1 TAP STRIP ASSEMBLY
31309S 1 VARISTOR ASSEMBLY, VR1, 320V
31301S 2 DOOR LATCH, BASE
31302S 2 DOOR LATCH, STUD

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14. WIRING DIAGRAM