Nautel NAB05E Owner's manual
web: www.nautel.com
Nautel Maine Inc. Nautel Limited
201 Target Industrial Circle, 10089 Peggy’s Cove Road,
Bangor, Maine USA 04401 Hackett’s Cove, NS, Canada B3Z
3J4
Phone: (207) 947-8200 Phone: (902) 823-3900
Fax: (207) 947-3693 Fax: (902) 823-3183
ISO 9002 REGISTERED ISO 9001 REGISTERED
© Copyright 2004 NAUTEL. All rights reserved
TECHNICAL INSTRUCTIONS
NAB05E
BATTERY CHARGER
(48 Volt)
VARIATIONS INCLUDED
NAB05E/01 - 115 V AC (Line-to - Neutral)
NAB05E/02 - 250 V AC (Line to - Neutral)
Original Issue ...............01 September 2004
48 VOLT BATTERY CHARGER
NAB05E
Effective Pages (Page 1)
01 September 2004
LIST OF EFFECTIVE PAGES
The list of effective pages lists the status of all pages in this manual. Pages of the original issue are identified by a
zero in the Change No. column. Pages subsequently changed are identified by the date of the change number. On a
changed page, the text affected by the latest change is indicated by a vertical bar in the margin opposite the changed
material.
Original ................................................ 01 September 2004
Total number of printed sides in this manual is 45 as listed below:
CHANGE CHANGE
PAGE No. DATE PAGE No. DATE
Title 0 01 September 2004
Title (Rear) - Blank
Effective (1) 0 01 September 2004
Effective (2) - Blank
Safety (1) 0 01 September 2004
Safety (2) 0 01 September 2004
Safety (3) 0 01 September 2004
Safety (4) - Blank
Warranty (1) 0 01 September 2004
Warranty (2) 0 01 September 2004
Contents (1) 0 01 September 2004
Contents (2) 0 01 September 2004
Contents (3) 0 01 September 2004
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1-1 0 01 September 2004
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7-6 0 01 September 2004
SD-1 0 01 September 2004
SD-2 0 01 September 2004
MD-1 0 01 September 2004
MD-2 0 01 September 2004
MD-3 0 01 September 2004
48 VOLT BATTERY CHARGER
NAB05E
Safety (Page 1)
01 September 2004
ARTIFICIAL RESPIRATION (MOUTH-TO-MOUTH)
(a) START MOUTH-TO-MOUTH BREATHING IMMEDIATELY.
SECONDS COUNT. Do not wait to loosen clothing, warm the
casualty, or apply stimulants.
(b) ASSESS RESPONSIVENESS OF CASUALTY. Do not jar
casualty or cause further physical injury (Figure 1)
(c) IF POSSIBLE, SEND A BYSTANDER TO GET MEDICAL
HELP. Do not leave casualty unattended (Figure 2)
(d) CHECK CAROTID PULSE (Figure 3)
(e) LAY CASUALTY ON HIS/HER BACK and place any
available jacket or blanket under his/her shoulders.
(f) TILT THE HEAD BACK AND LIFT THE CHIN to open the
airway (Figure 4)
(g) PINCH CASUALTY’S NOSE AND EXHALE TWO SLOW
BREATHS INTO CASUALTY (Figure 5)
(h) REMOVE YOUR MOUTH and check for breathing (Figure 6)
(i) CONTINUE GIVING ONE BREATH EVERY FIVE SECONDS
without interruption. If any air is retained in the stomach after
exhalation by casualty, press gently on stomach to expel air.
(j) IF CHEST DOES NOT RISE CHECK for obstruction in
casualty’s mouth: clear foreign material using your finger,
tissues, etc. Use chin lift and recommence mouth-to-mouth
breathing.
(k) WHILE MOUTH-TO-MOUTH BREATHING IS CONTINUED
have someone else:
(a) Loosen casualty’s clothing.
(b) Keep the casualty warm.
(l) DON’T GIVE UP. Continue without interruption until the
casualty is revived, or until a doctor pronounces the casualty
dead. Four hours or more may be required.
(m) DO NOT PROVIDE ANYTHING ORALLY while victim is
unconscious.
1
2
3
4
5
6
48 VOLT BATTERY CHARGER
NAB05E
Safety (Page 2)
01 September 2004
GENERAL RULES FOR TREATMENT FOR BURNS, BLEEDING, AND SHOCK
1. After casualty has revived, treat for injuries and shock.
2. Reassure casualty.
3. Try to make him comfortable.
4. Keep him reasonably warm but do not apply heat.
5. If thirsty, liquids may be given but no alcohol (no liquids should be given in cases of severe burns).
6. Treat burns or wounds. Infection danger in treating burns or wounds is very great so ensure hands are
clean and do not handle affected areas more than necessary.
7. Do not apply salves, grease, etc. to burns.
8. Do not remove burned clothing which adheres to the skin or break blisters.
9. Cover the burn with a dry sterile dressing, piece of sheeting, etc.
10. Bandage lightly over blisters where care must be taken to cover and not to break.
11. If severe bleeding of wound, elevate affected area, except in the case of a fracture.
12. Expose wound and apply pressure.
13. Apply dressing, pad and bandage.
14. For burns and bleeding, immobilize injured part using splints if necessary and keep patient in restful
position during removal to hospital or expert medical attention.
15. In all cases, send for medical aid immediately.
48 VOLT BATTERY CHARGER
NAB05E
Safety (Page 3)
01 September 2004
ELECTRIC SHOCK - RESCUE METHODS
Electricity can damage the body in a number of ways. It may interfere with the proper functioning of the nervous
system and the heart action, it can subject the body to extreme heat and can cause severe muscular contractions. The
path that the current of electricity takes through the body is important. Currents which pass from hand to hand or
from hand to foot may pass directly through the heart and upset its normal functioning. This threat to life is related to
the amount of current or amperage that will flow through a victim's body. Very little current (as little as 10 milliamps)
can result in severe shock or death.
Speed in the application of first aid measures is absolutely essential in cases of electrical injury. As soon as the victim
is freed safely from the source of the electrical current, if breathing has stopped, artificial respiration should be
commenced immediately. If the carotid pulse cannot be felt, external cardiac massage should be commenced
simultaneously. Resuscitation should be continued until the patient is breathing on his own or until medical aid
arrives. Survival rates can be quite high if cardio-pulmonary resuscitation is started within 3 to 4 minutes of the injury
being received.
ACT AT ONCE - DELAY OR INDECISION MAY BE FATAL
1. Turn OFF the electrical source.
2. Commence artificial respiration immediately.
3. Treat for burns, bleeding and shock.
REMOVING A CASUALTY FROM ELECTRICAL CONTACT
LOW VOLTAGE - 0 to 240 volts (household use)
Switch off the current, if possible and time permits. If the switch cannot be located immediately and the supply is
through a flexible cord or cable, the current may be shut off by removing the plug or even breaking the cable or
wrenching free. Never attempt to shut off current by cutting cord with a knife or scissors.
If the current cannot be shut off, the greatest care is necessary in removing the casualty. Household rubber gloves,
rubber or plastic hose (if there is no water in them), a dry unpainted stick or a clean dry rope can be used to free
victim.
HIGH VOLTAGE - 240 volts and up (industrial machines and power lines)
Do not touch any person or equipment in contact with a wire.
Use a dry unpainted pole, clean dry rope, dry rubber or plastic water hose to separate the casualty from the contact.
Keep as far away as possible.
Do not touch the casualty until he is free.
48 VOLT BATTERY CHARGER
NAB05E
Safety (Page 4)
01 September 2004
TOXIC HAZARD WARNING
There are devices used in this equipment containing BERYLLIUM OXIDE ceramic, which is non-hazardous
during normal device operation and under normal device failure conditions. These devices are specifically
identified in the equipment manual’s parts list(s).
DO NOT cut, crush or grind devices because the resulting dust may be HAZARDOUS IF INHALED.
Unserviceable devices should be disposed of as harmful waste.
48 VOLT BATTERY CHARGER
NAB05E
Warranty (Page 1)
01 September 2004
WARRANTY
Nautel Limited/Nautel Maine Incorporated, hereinafter referred to as Nautel, guarantees all mechanical and electrical
parts of the equipment for a period of thirteen months from date of shipment.
1. A "Part Failure" shall be deemed to have occurred when the part has become defective, or does not have the
characteristics required for the specified equipment performance:
(a) When the equipment is operated within the design parameters, and
(b) When the equipment is installed and adjusted according to Nautel's prescribed procedures as stated in the
instruction manual.
2. Nautel shall provide replacements for all "Parts" at no cost to the Customer when they become defective during
the warranty period, and upon the return of the defective part.
3. In the event that a "Part" fails during the warranty period and causes damage to a sub-assembly that cannot be
readily repaired in the field, the entire sub-assembly so damaged may be returned to Nautel for repair. The
repairs will be made without charge to the Customer.
4. Where warranty replacements or repair are provided under items 2 or 3, Nautel will pay that part of the
shipping costs incurred in returning the part/assembly to the Customer.
5. Warranty replacement parts and repair, which are provided under items 2 or 3, shall be guaranteed for a period
of ninety days from date of shipment or until the end of the original warranty period, whichever occurs later.
6. Nautel will not assume responsibility for any charges incurred by other than Nautel employees.
7. Nautel shall have the privilege of investigating whether failures have been caused by factors beyond its
control.
8. Nautel shall in no event be liable for any consequential damages arising from the use of this equipment.
9. When requesting a warranty repair/replacement, please provide complete and accurate information. Observe
the instructions regarding 'Equipment Being Returned to Nautel' on page two of this warranty and provide the
information requested.
10. When ordering spare/replacement parts; please provide complete and accurate information. Refer to the parts
list of this manual for ordering information. Provide as much of the information requested for 'Equipment
Being Returned to Nautel' on page two of this warranty as is practical. The information identified by an
asterisk is the minimum required.
ON-LINE PART QUOTES
Nautel provides an on-line website service (www.nautel.com/in-service.html) where requests for part quotes may
be submitted. Requests will normally be responded to within one working day.
48 VOLT BATTERY CHARGER
NAB05E
Warranty (Page 2)
01 September 2004
FACTORY SUPPORT
TECHNICAL ASSISTANCE
Nautel's field service department provides telephone technical assistance on a 24 hour, seven days a week basis.
Requests by other media (facsimile or e-mail) will be responded to the next working day if received after Nautel's
normal working hours. Contact the appropriate field service centre from the following:
U.S.A. customers use: Nautel Maine Incorporated Telephone 207-947-8200 (24 hours)
201 Target Industrial Circle Facsimile 207-947-3693
Bangor, Maine 04401
All other customers use: Nautel Limited Telephone 902-823-3900 (24 hours)
10089 Peggy’s Cove Road Facsimile 902-823-3183
B3Z 3J4 Web www.nautel.com
MODULE EXCHANGE SERVICE
In order to provide Nautel customers with a fast and efficient service in the event of a problem, Nautel operates a
factory rebuilt, module exchange service which takes full advantage of the high degree of module redundancy in
Nautel equipment. This module exchange service is operated from Nautel’s factory in Bangor, Maine and
Hackett’s Cove, Nova Scotia. These two locations allow us to provide a quick turn around service to keep our
customers on the air. During the transmitter’s warranty period, up to thirteen months from shipment, repair and
exchange of modules is at no charge to the customer. When the warranty has expired, a charge of 80% of the list
price for all exchanged modules is made. If the faulty module is returned to Nautel within 30 days, a credit is
issued reducing this charge by one half to 40% of the list price. U.S.A. customers are required to contact our
Bangor, Maine facility. Canadian and overseas customers should contact our Nova Scotia, Canada facility.
EQUIPMENT BEING RETURNED TO NAUTEL
All equipment being returned to Nautel and all requests for repairs or replacements should be marked 'field return'
and addressed to the appropriate Nautel facility.
Complete and accurate information regarding the equipment being returned will ensure prompt attention and will
expedite the dispatch of replacements. Refer to the nameplate on the transmitter and/or the appropriate
module/assembly to obtain name, type, part and serial number information. Refer to the parts list of this manual or
the appropriate service instruction manual for additional ordering information.
The following information should accompany each request:
* Model of Equipment
* Serial number of Equipment
* Name of Part/Assembly
Serial number of Part/Assembly
* Complete reference designation of Part/Assembly
* Nautel's part number of Part/Assembly
* OEM's part number of Part/Assembly
Number of hours in Use
Nature of defect
* Return shipping address
* Denotes minimum information required to order spare/replacement parts
48 VOLT BATTERY CHARGER
NAB05E
Contents (Page 1)
01 September 2004
TABLE OF CONTENTS
Section Page
1 - GENERAL INFORMATION
1.1 INTRODUCTION ...................................................................................................................................1-1
1.2 TECHNICAL SUMMARY......................................................................................................................1-1
1.3 MECHANICAL DESCRIPTION ............................................................................................................1-1
1.4 SPECIAL TOOLS AND TEST EQUIPMENT .......................................................................................1-1
2 - THEORY OF OPERATION
2.1 GENERAL .............................................................................................................................................2-1
2.2 BATTERY CHARGER OVERVIEW .....................................................................................................2-1
2.2.1 AC POWER SUPPLY OVERVIEW.......................................................................................................2-1
2.2.2 23 VDC POWER SUPPLY OVERVIEW...............................................................................................2-1
2.2.3 15 VDC POWER SUPPLY OVERVIEW...............................................................................................2-1
2.2.4 DIGITIZER OVERVIEW ........................................................................................................................2-1
2.2.5 RAMP GENERATOR OVERVIEW .......................................................................................................2-2
2.2.6 VOLTS COMPARATOR OVERVIEW...................................................................................................2-2
2.2.7 EIGHT SECOND TIMER OVERVIEW..................................................................................................2-2
2.2.8 CHARGING CURRENT CONTROL OVERVIEW................................................................................2-2
2.2.9 THYRISTOR TURN-ON OVERVIEW...................................................................................................2-2
2.2.10 FULL-WAVE RECTIFIER OVERVIEW.................................................................................................2-3
2.3 DETAILED DESCRIPTION...................................................................................................................2-3
2.3.1 AC POWER SUPPLY............................................................................................................................2-3
2.3.2 23 VDC POWER SUPPLY....................................................................................................................2-3
2.3.3 15 VDC POWER SUPPLY....................................................................................................................2-3
2.3.4 DIGITIZER .............................................................................................................................................2-4
2.3.5 RAMP GENERATOR ............................................................................................................................2-4
2.3.6 BATTERY VOLTAGE COMPARATOR ................................................................................................2-4
2.3.7 EIGHT SECOND TIMER ......................................................................................................................2-5
2.3.8 CHARGING CURRENT CONTROL .....................................................................................................2-5
2.3.9 THYRISTOR TURN-ON CONTROL.....................................................................................................2-5
2.3.10 FULL-WAVE RECTIFIER......................................................................................................................2-6
3 - INSTALLATION AND PREPARATION FOR USE
3.1 GENERAL .............................................................................................................................................3-1
3.2 TEST EQUIPMENT ...............................................................................................................................3-1
3.3 SITE REQUIREMENTS ........................................................................................................................3-1
3.3.1 ELECTRICAL POWER..........................................................................................................................3-1
3.3.2 ELECTRICAL POWER CABLE ............................................................................................................3-1
3.3.3 BATTERY CABLE .................................................................................................................................3-1
3.4 UNPACKING .........................................................................................................................................3-1
3.5 ANCILLARY PARTS ............................................................................................................................3-1
3.6 INFORMATION TO BE DETERMINED PRIOR TO FINAL INSTALLATION ....................................3-1
3.6.1 AC POWER SOURCE ..........................................................................................................................3-1
3.6.2 TYPE OF BATTERY..............................................................................................................................3-1
3.6.3 BATTERY VOLTAGE (NO LOAD)........................................................................................................3-1
3.6.4 CHARGING CURRENT ........................................................................................................................3-1
3.6.5 SPECIFIC GRAVITY .............................................................................................................................3-1
48 VOLT BATTERY CHARGER
NAB05E
Contents (Page 2)
01 September 2004
TABLE OF CONTENTS (Continued)
Section Page
3 - INSTALLATION AND PREPARATION FOR USE (Continued)
3.7 PARTS REQUIRED BUT NOT SUPPLIED .........................................................................................3-2
3.7.1 AC POWER CABLE ..............................................................................................................................3-2
3.7.2 BATTERY CABLE .................................................................................................................................3-2
3.8 INSTALLATION PROCEDURES .........................................................................................................3-2
3.8.1 PHYSICAL MOUNTING ........................................................................................................................3-2
3.8.2 SELECTING PROPER TAPS OF POWER TRANSFORMER T1.......................................................3-2
3.8.3 CONNECTION OF AC POWER WIRING ............................................................................................3-2
3.8.4 CONNECTION OF BATTERY INTERCONNECTING WIRING ..........................................................3-2
3.8.5 POSITIONING OF BATTERY TEMEPRATURE SENSOR .................................................................3-3
3.8.6 POST-INSTALLATION INSPECTION ..................................................................................................3-3
3.9 INITIAL TURN-ON PROCEDURES .....................................................................................................3-3
4 - OPERATING INSTRUCTIONS
4.1 GENERAL .............................................................................................................................................4-1
4.2 EMERGENCY SHUTDOWN PROCEDURE........................................................................................4-1
4.3 PERSONNEL SAFETY.........................................................................................................................4-1
4.4 CONTROLS AND INDICATORS .........................................................................................................4-1
4.5 TURNING ON THE BATTERY CHARGER .........................................................................................4-1
4.6 OPERATING PRECAUTIONS .............................................................................................................4-1
4.7 FAULT INDICATION.............................................................................................................................4-2
5 - ADJUSTMENT AND TESTING
5.1 GENERAL .............................................................................................................................................5-1
5.2 TEST EQUIIPMENT REQUIRED .........................................................................................................5-1
5.3 ADJUSTMENT PROCEDURES...........................................................................................................5-1
5.3.1 OPERATION OF EQUIPMENT ...........................................................................................................5-1
5.3.2 ADJUSTMENT PRE-REQUISITES .....................................................................................................5-1
5.3.3 ADJUSTMENT METHOD 1 .................................................................................................................5-1
5.3.4 ADJUSTMENT METHOD 2 .................................................................................................................5-2
5.4 FUNCTIONAL TEST.............................................................................................................................5-4
6 - MAINTENANCE
6.1 GENERAL .............................................................................................................................................6-1
6.2 SCHEMATICS/LOGIC DIAGRAMS .....................................................................................................6-1
6.2.1 COMPONENT VALUES........................................................................................................................6-1
6.2.2 GRAPHIC SYMBOLS............................................................................................................................6-1
6.2.3 LOGIC SYMBOLS .................................................................................................................................6-1
6.2.4 REFERENCE DESIGNATIONS ...........................................................................................................6-1
6.3 WIRING INFORMATION ......................................................................................................................6-1
6.4 MECHANCIAL DRAWINGS.................................................................................................................6-1
6.5 TEST EQUIPMENT ...............................................................................................................................6-1
6.6 SCHEDULED MAINTENANCE............................................................................................................6-1
6.7 CORRECTIVE MAINTENANCE...........................................................................................................6-1
48 VOLT BATTERY CHARGER
NAB05E
Contents (Page 3)
01 September 2004
TABLE OF CONTENTS (Continued)
Section Page
7 - PARTS LIST
7.1 INTRODUCTION ...................................................................................................................................7-1
7.2 FAMILY TREE .......................................................................................................................................7-1
7.3 MANUFACTURER'S INDEX ................................................................................................................7-1
7.4 HOW TO LOCATE INFORMATION FOR A SPECIFIC PART...........................................................7-1
7.5 REFERENCE DESIGNATION INDEXES ............................................................................................7-1
7.6 COLUMN CONTENT EXPLANTATION ..............................................................................................7-1
7.6.1 USE CODE COLUMN ...........................................................................................................................7-1
7.6.2 REF DES COLUMN ..............................................................................................................................7-2
7.6.3 NAME OF PART AND DESCRIPTION COLUMN ...............................................................................7-2
7.6.4 NAUTEL'S PART NO COLUMN ...........................................................................................................7-2
7.6.5 JAN, MIL or MFR PART NO COLUMN ................................................................................................7-2
7.6.6 (OEM) CODE COLUMN........................................................................................................................7-2
LIST OF ILLUSTRATIONS
Number Title Page
2-1 Timing Information ...........................................................................................................................................2-7
6-1 Waveforms .......................................................................................................................................................6-4
SD-1 Block Diagram - NAB05E Battery Charger ..................................................................................................SD-1
SD-2 Electrical Schematic - NAB05E Battery Charger .........................................................................................SD-2
MD-1 Assembly Detail - NAB05E Battery Charger............................................................................................... MD-1
MD-2 Assembly Detail - Battery Charger PWB (P/N 147-1310-08)..................................................................... MD-2
MD-3 Dimensional Information - NAB05E Battery Charger ................................................................................. MD-3
LIST OF TABLES
Number Title Page
1-1 Technical Summary .........................................................................................................................................1-1
1-2 Test Equipment................................................................................................................................................1-2
6-1 System Troubleshooting Assistance Chart.....................................................................................................6-2
6-2 Wiring List - NAB05E Battery Charger............................................................................................................6-3
7-1 Manufacturers' Code to Address Index...........................................................................................................7-3
7-2 Ref Des Index - NAB05E Battery Charger......................................................................................................7-5
48 VOLT BATTERY CHARGER
NAB05E
Page 1-1
01 September 2004
SECTION 1
GENERAL INFORMATION
INTRODUCTION
1.1 The battery charger is a pulsed current,
battery charger that will provide a constant charging
current of up to 3.0 amperes to a nominal 48 volt
battery bank. The battery charger is intended to be
used with a battery bank that has a full charge, no
load, voltage of 51.0 to 67.0 volts. The charging
current is applied to the battery bank in eight second
pulse strings, with the time between pulses
determined by the charge status of the batteries.
When the battery bank is deeply discharged, the pulse
strings will occur continuously and then decrease
towards an infinite level as the battery bank reaches
its full charge voltage.
TECHNICAL SUMMARY
1.2 Table 1-1 - Technical Summary, contains a
detailed technical summary.
MECHANICAL DESCRIPTION
1.3 The battery charger comprises an enclosed,
semi-watertight, steel cabinet with external
connections made through cable entry holes in the
bottom of the cabinet and connected to two terminal
blocks on the rear panel inside the cabinet. The
battery charger circuitry, comprising a supply
transformer; choke; two thyristors; two fuses; one
power on/off switch and a printed wiring board
(PWB) assembly, is mounted on the rear panel on a
metal plate inside the steel cabinet. A hinged door,
that can be opened by loosening six securing clamps,
provides easy access to the circuitry.
SPECIAL TOOLS AND TEST EQUIPMENT
1.4 There are no special tools required to
maintain the battery charger. Table 1-2 - Test
Equipment, lists the test equipment recommended for
calibration, testing and maintenance.
Table 1-1 Technical Summary
Equipment Name:....................................................................................................................... 48 Volt Battery Charger
Nautel Equipment Type Number:...................................................................................................................... NAB05E
Battery Charging Data:
Battery Voltage (Full charge, no load) ............................................................................................ 51.0 to 67.0 Volts
Charging Current...........................................................................................Adjustable up to 3 amperes (maximum)
.............................................. into a discharged battery
Power Requirements:
NAB05E/01.....................................................................................115 V ac (Line-to-Neutral), 50/60 Hz@ 250 VA
NAB05E/02.....................................................................................230 V ac (Line-to-Neutral), 50/60 Hz@ 250 VA
Environmental Limits:
Temperature..........................................................................................................................................-10°C to +55°C
Relative humidity ............................................................................................................................................0 to 90%
Dimensions
Height ............................................................................................................................................... 14 inches (35 cm)
Width ................................................................................................................................................ 12 inches (30 cm)
Depth .................................................................................................................................................. 6 inches (15 cm)
Weight ...............................................................................................................................................40 pounds (18.2 kg)
48 VOLT BATTERY CHARGER
NAB05E
Page 1-2
01 September 2004
Table 1-2 Test Equipment
PART, MODEL, OR TYPE NUMBER
NOMENCLATURE (EQUIVALENTS MAY BE USED) APPLICATION
Digital Voltmeter Any good quality 3 1/2 digit digital
voltmeter
Measure ac/dc voltages and
resistance during calibration and
trouble shooting procedures
DC Ammeter 5 amperes measurement capability Precise measurement of dc
charge current.
Hydrometer Any good quality hydrometer with a
calibrated specific gravity scale.
Measurement of specific gravity
of battery electrolyte.
Oscilloscope Any good quality oscilloscope with a
calibrated time base.
Monitor waveforms during
trouble shooting procedures
♦Dc Power Supply Any good quality dc power supply
(0 - 70 volts)
Simulate precise, full charge, no
load, battery voltage during
calibration.
♦Variac Any good quality variac with an input
voltage rated at the ac voltage to be
applied to the battery charger. Output
voltage must be rated at a minimum of
250 Va and allow adjustment of plus or
minus ten percent of nominal input ac
voltage.
Varies ac power source voltage
during calibration.
NOTE:♦- Denotes these items of test equipment are optional. They are not necessary if the
simplified procedures of paragraph 5.3.3 are used for test and adjustment. If the
detailed test/adjustment procedure of paragraph 5.3.4 is to be used, they are required.
48 VOLT BATTERY CHARGER
NAB05E
Page 2-1
01 September 2004
SECTION 2
THEORY OF OPERATION
GENERAL
2.1 The theory of operation for the battery
charger is presented in this section. The information
is presented in detail using figure SD-2 - electrical
schematic as a reference.
BATTERY CHARGER OVERVIEW
2.2 The 48 volt dc battery charger operates on
the principle that the terminal voltage of batteries
being charged will eventually stabilize at a voltage
that can be predetermined when they are fully
charged, under no load conditions. Prior to reaching
the full-charge condition, the battery terminal voltage
will approach or reach this full charge voltage when a
charging current is being applied and then decay to a
lesser voltage when the charging current is removed.
If the battery terminal voltage is compared to a
reference voltage that is slightly less than the
full-charge, no load, terminal voltage, it will take
progressively longer for the battery terminal voltage
to decay to a level that is less than the reference
voltage as the battery approaches the full charge
condition. This feature is utilized in the battery
charger and is used to control the application of eight
second bursts of current to the batteries being charged.
When the batteries are in a discharged condition, the
eight second current bursts will occur at frequent
intervals. As the batteries approach the fully charged
condition, the eight second current bursts will occur
less frequently until the interval time is nearly infinite.
The following provides an overview of the subject
battery charger, using the block diagram shown in
figure SD-1.
2.2.1 AC POWER SUPPLY OVERVIEW:
The ac power supply consists of an EMI filter, an on/
off switch, a fuse and a power transformer. The EMI
filter, removes unwanted transients from the ac power
source. The power transformer has two identical 115
volt primary windings and two sets of secondary
windings. When the ac power source voltage is 115
vac, 60 Hz, the primary windings of the power
transformer are connected in parallel. When the ac
power source voltage is 230 V ac, 50 Hz, the primary
windings are connected in series. One set of
secondary windings provides 17.5 V ac, RMS for the
low voltage power supplies. The second set of
secondary windings provides a centre tapped 150
(75-0-75) V ac RMS for the battery charging dc
voltage source.
2.2.2 23 V DC POWER SUPPLY OVERVIEW:
The 17.5 volt ac, RMS voltage from the power
transformer is applied to a full-wave bridge rectifier.
The output of the bridge rectifier will be an
unregulated, ripple, dc voltage with a nominal level of
23 V dc. The ripple frequency will be twice the
frequency of the ac power source. Their are two
outputs from the 23 V dc power supply, one is the
unsmoothed, ripple, dc voltage and the other is a
smoothed, unregulated, 23 V dc. The dc return path
for the 23 V dc power supply is not connected to
chassis ground but is connected to the positive
terminal of the battery voltage. This point is the dc
reference level for all of the logic circuits. A light
emitting diode is connected across the 23 V dc output
and will indicate the battery charger is functioning by
turning on when 23 V dc is present.
2.2.3 15 V DC POWER SUPPLY OVER-
VIEW: The regulated 15 V dc power supply consists
of an integrated circuit device that acts as a voltage
regulator. The output of the regulator is maintained at
+15 V dc with respect to the same dc reference level
as the 23 V dc power supply, regardless of the
fluctuations in the output of the 23 V dc power supply
output.
2.2.4 DIGITIZER OVERVIEW: A logic
circuit compares the ripple dc voltage from the
unregulated 23 V dc power supply to a fixed, dc refer-
ence voltage and produces a rectangular waveform at
the ripple frequency. The frequency of the ripple and
therefore the repetition frequency of the rectangular
waveform is twice the frequency of the ac power
source. The rectangular waveform will be high (+23
V dc) when the reference voltage is more positive
than the ripple voltage. It will remain in this state for
a relatively short duration. It will switch low (dc
reference level) when the reference voltage is less
positive than the ripple voltage and will remain in this
state until the ripple voltage falls below the reference
voltage.
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2.2.5 RAMP GENERATOR OVERVIEW:
The ramp generator consists of a switching transistor
and an integrating circuit. When a 'ramp inhibit'
signal is not applied to the ramp generator from the 8-
second timer; a 'high' output from the digitizer will
turn on the transistor. When the transistor is turned
on, the voltage across the capacitor in the integrating
circuit, which is the output of the ramp generator, will
discharge to the dc reference level. When the output
of the digitizer, switches to 'low', the transistor will
turn off. The capacitor in the integrating circuit will
charge towards +23 V dc. The ramp generator's
output will be a relatively linear ramp voltage (the
R/C time constant of the integrating circuit is long at
the switching repetition rate), that increases from the
dc reference level to a positive dc voltage. A linear
ramp waveform will be generated for each half cycle
of the ac power supply voltage applied to the 23 V dc
power supply. When a 'ramp inhibit' signal is applied
to the ramp generator, the charging voltage for the
capacitor in the integrating circuit is removed and the
ramp generator's output will be maintained at the dc
reference level.
2.2.6 VOLTS COMPARATOR OVERVIEW:
The battery voltage comparator circuit utilizes a logic
circuit that compares the battery terminal voltage to a
temperature compensated, adjustable, reference
voltage. The reference voltage is preset to a level that
is slightly below the fully charged, no load, terminal
voltage of the battery. The fully charged, no load
terminal voltage of batteries with different electrolyte
will differ. The precise no load, voltage; of the
batteries to be charged must be obtained from the
battery manufacturer. When the battery terminal
voltage decays to a level that is below the reference
voltage, the output of the logic circuit generates a
'master reset' signal for an eight second timer. If the
battery terminal voltage does not decay to a level that
is below the reference voltage, the 'master reset' signal
is not generated. A temperature sensor, that is
monitoring the ambient air in the vicinity of the
batteries, automatically changes the reference voltage
with changes in temperature. This feature reduces
boiling off of battery electrolyte, when the ambient
temperature is high, by lowering the reference voltage
as the sensed temperature increases and effectively
increasing the time required to generate a 'master
reset' signal as the batteries approach their fully
charged condition.
2.2.7 EIGHT SECOND TIMER
OVERVIEW: An oscillator/timer integrated circuit
device is used as the eight second timer. In the
absence of a 'master reset' signal, the output of the
eight second timer will apply a 'ramp inhibit' signal to
the ramp generator. When a 'master reset' is applied,
the timer will remove the 'ramp inhibit' signal for
eight seconds and then reapply it until the next 'master
reset' signal is generated.
2.2.8 CHARGING CURRENT CONTROL
OVERVIEW: The charging current control circuit
consists of an operational amplifier that produces an
adjustable dc voltage as its 'control voltage'. The
control voltage is proportional to the differ-ence
between a dc reference and a dc voltage (charging
current voltage) that is representative of the battery
charging current. The 'charging current voltage' is
developed across a resistor in the battery charging
circuit. The dc reference voltage is adjusted, during
calibration, to a level that represents the maximum
charge current to be applied to the batteries. When
current is being applied to the batteries at the desired
magnitude, the 'charging current voltage' will be equal
to the dc reference voltage. The resultant 'control
voltage' output will stabilize to a level that will cause
the 'thyristor control' pulse to be generated during the
portion of each ac power supply voltage half cycle
that will result in the average dc voltage output, of the
switched full-wave rectifier, maintaining the charging
current at the desired level. If the charging current
attempts to change, as the result of the internal
resistance of the battery changing, the 'control voltage'
output will change in the appropriate direction
(increase if less current is required or decrease if more
current is required) and cause the 'thyristor control'
pulse to be generated later or earlier in each ac power
supply voltage half cycle and maintain the charging
current at the desired level.
2.2.9 THYRISTOR TURN-ON OVERVIEW:
The thyristor turn-on control consists of a comparator
and a switching transistor. The comparator compares
the voltage level of the ramp generator's output to the
'control voltage' output of the charging current control
circuit. When the ramp generator's output is less
positive than the 'control voltage', the comparator's
output will be a high (+23 V dc) level and the switch-
ing transistor will be turned off. An output will not be
produced by the thyristor turn-on control circuit.
When the ramp voltage goes more positive than the
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'control voltage', the comparator's output will switch
to a low (dc reference) level and cause the switching
transistor to turn on. A positive voltage, 'thyristor
control' pulse will be applied to the control gate of
both thyristors in the switched full-wave rectifier
circuit. Since the ramp voltage increases linearly with
time and it is reset to the dc reference voltage, at the
start of each half cycle of the ac voltage applied to the
unregulated 23 volt dc bridge rectifier, the level of the
'control voltage' will determine at what point of time,
relative to the start of each ac voltage half cycle, the
leading edge of the 'thyristor control' pulse will occur.
As the 'control voltage' goes more positive, the
leading edge of the 'thyristor control' pulse will occur
at a progressively later period of time. As the 'control
voltage' goes less positive, the leading edge of the
'thyristor control' pulse will occur at an earlier period
of time.
2.2.10 FULL-WAVE RECTIFIER
OVERVIEW: The switched full-wave rectifier
circuit produces a dc voltage that maintains the battery
charging current at the preset, desired level when a
'thyristor control' pulse is applied. The circuit consists
of two thyristors that have the ac voltage on the centre
tapped secondary (75-0-75 volts RMS ac) of the ac
power supply applied to their anodes. The voltage on
each anode is 180 degrees out of phase with the other;
but, since they are obtained from the same transformer
as the ac power source for the unregulated 23 volt dc
bridge rectifier, the crossover point for each half cycle
will be synchronized with the start of the ramp
waveform output of the ramp generator. The
'thyristor control' pulse will occur at some point of
time during each half cycle. Each thyristor will only
turn on when its anode is positive relative to its
cathode and it will remain on for the remainder of that
half cycle. The output of the switched full- wave
rectifier circuit will be dc voltage pulses with an
average value determined by the period of each half
cycle that the thyristors are turned on. When the
'thyristor control' pulses occur at the appropriate time,
this average dc voltage will maintain the battery
charging current at the desired, preset level. A choke
is installed in the centre tapped ac return path to filter
the average dc voltage. It also contains a free
wheeling diode that prevents oscillations when the
'thyristor control' pulses are removed and the current
in the choke collapses.
DETAILED DESCRIPTION
2.3 The following provides an in-depth under-
standing of complex or non-obvious circuit functions.
The descriptions are keyed to the block diagram
referenced in paragraph 2.2 and expand on the
associated block diagram descriptions.
2.3.1 AC POWER SUPPLY: The ac power
source (115 volts ac RMS, 60 Hz or 230 volts ac
RMS, 50 Hz) is connected between TB1-4 (line) and
TB1-5 (neutral) with the ac ground connected to the
safety ground stud. The ac line is applied thru EMI
filter U2 thru POWER switch S1, thru fuse F1, thru
TB1-1 to one side of power transformer T1's primary
windings. The ac neutral is connected to the other
side of T1's primary windings thru TB1-2. Power
transformer T1 has two identical 115 volt primary
windings. Two sets of secondary windings provide
the step down voltages required by the battery
charger's dc power supplies. One set of secondary
windings provides 17.5 V ac, RMS and the other set
provides a centre tapped 150 (75-0-75) V ac RMS.
2.3.2 V DC POWER SUPPLY: 17.5 V ac,
RMS, from power transformer T1, is applied to
full-wave bridge rectifier A1U1. The resultant output
of A1U1 is a nominal 23 V dc, which is not regulated
and contains a ripple component that is twice the
frequency of the ac power source. This ripple dc
voltage is applied to the inverting input of comparator
A1U3A and thru diode A1CR1 to smoothing
capacitor C1. Smoothing capacitor C1 smooths the
unregulated 23 V dc output to an acceptable level,
while RF bypass capacitor A1C1 removes any high
frequency component. The negative side of the 23 V
V dc power supply is not connected to chassis ground
but is connected to the positive voltage side of the
battery charging voltage (positive battery terminal).
This point is the dc reference level for all of the logic
circuits. Light emitting diode DS1 will turn on when
the 23 V dc power supply is producing an unregulated
23 V dc output.
2.3.3 15 V DC POWER SUPPLY: The
smoothed unregulated 23 V dc is applied to the input
of 15 V dc regulator A1U1. The output of 15 V dc
regulator A1U1 is maintained at +15 V dc with
respect to the dc reference level, regardless of the
fluctuations in the unregulated 23 V dc, provided it
remains above 15 V dc.
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2.3.4 DIGITIZER: The digitizer consists of
operational amplifier A1U3A, which is employed as a
comparator, and its associated components. Resistors
A1R3/R4 form a voltage divider that applies a
nominal +0.18 V dc, from their junction, to the
non-inverting input of A1U3A as a reference voltage.
The unregulated, 23 volt dc ripple voltage, from the
23 volt dc power supply is applied to A1U3A's
inverting input. When the ripple voltage is less
positive than the reference voltage on its
non-inverting input, the output of A1U3A will be high
(23 V dc). When the ripple voltage is more positive
than the reference voltage, the output of A1U3A will
be low (dc reference level). Since each ripple in the
23 volt dc ripple voltage input represents one half
cycle of the ac power source, the resultant output of
A1U3A is a rectangular waveform that goes high
shortly after the start of each half cycle of the ac
power source; remains high for a relatively short
period of time and then goes low for the remainder of
the half cycle. The repetition frequency of the
rectangular waveform will be twice the frequency of
the ac power source.
2.3.5 RAMP GENERATOR: The ramp
generator consists of A1Q1, resistors A1R5/R6/R7
and capacitor A1C4. The rectangular waveform
output of A1U3A is applied to the base of transistor
A1Q1, which is employed as a switching transistor.
Resistors A1R5/R6 form a voltage divider that
ensures A1Q1's base does not exceed a nominal 2.0 V
dc when the output of A1U3A is 'high'. When the
rectangular waveform is 'high', A1Q1 will be forward
biased and it will turn on. When the rectangular
waveform is 'low', A1Q1 will be reverse biased and it
will turn off. Resistor A1R7 and Capacitor A1C4
form an integrating circuit that has a relatively long
time constant at the repetition frequency of the rec-
tangular waveform. When A1Q1 is turned on,
capacitor A1C4 will discharge instantly to the dc
reference level thru A1Q1. When A1Q1 is turned off,
capacitor A1C4 will charge towards 23 V dc thru
A1R7. A1Q1 will turn on again while A1C4 is in the
relatively linear portion of its charging curve,
resulting in a relatively linear ramp waveforms. The
switching action of A1Q1 is controlled by transistor
A1Q2, which in turn is controlled by the status of the
eight second timer. When A1Q2 is turned on, the
collector of A1Q1 will be clamped to the dc reference
level and the switching action of A1Q1 will be
inhibited. When A1Q2 is turned off, it is effectively
removed from the circuit and has no influence on
A1Q1. The output of the ramp generator will be an
eight second string of linear ramp waveforms, that are
synchronized with the start of each half cycle of the ac
power source, each time the eight second timer is
enabled. During the remainder of the time, the ramp
generator's output will be clamped to the dc reference
level.
2.3.6 BATTERY VOLTAGE
COMPARATOR: The battery voltage comparator
circuit consists of operational amplifier A1U3D,
which is employed as a comparator; OR gate A1U5D;
temperature transducer and their associated
components. The voltage present on the negative
battery terminal is applied to a voltage divider formed
by resistors R2/A1R11. The resultant voltage at their
junction will be a negative voltage that is
approximately nine percent of the sensed voltage.
Resistor A1R22 and zener diode A1CR2 form a
voltage clamp that is connected between this negative
voltage and +15 V dc. The resultant voltage at the
junction of A1R22/ CR2, which is applied to the
inverting input of A1U3D, is clamped to a voltage
that is 9.0 V dc more positive than the negative volt-
age at the junction of R2/A1R11. This voltage is
representative of the battery voltage and will always
be a positive voltage, that will be the least positive
when the battery terminal voltage is maximum and
will go more positive as the battery terminal voltage
decays. Resistors A1R23/R24/R25 and temperature
transducer form a second voltage divider; that
provides an adjustable, temperature compensated,
positive, dc voltage to the non- inverting input of
A1U3D as a reference voltage. Potentiometer A1R24
is adjusted, during calibration, to provide a reference
voltage that is the same as or marginally more positive
than the voltage applied to the inverting input of
A1U3D, when the batteries are fully-charged. When
the battery terminal voltage is maximum, the voltage
on A1U3D's inverting input will be less positive than
the reference voltage on its non-inverting input and
the output of A1U3D will be 'high' (23 V dc). When
the battery terminal voltage decays to a level that will
cause the voltage on A1U3D's inverting input to be
more positive than the reference voltage on its
non-inverting input, the output of A1U3D will switch
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to low (dc reference level). Resistors A1R26/R27 are
connected as a voltage divider to ensure the voltage
applied to A1U5B-6 does not exceed +15 V dc when
the output of A1U3D is 'high'. The output of OR gate
A1U5B follows and inverts logic level changes on the
output of A1U3D, provided the input to A1U5B-5 is
being held 'low' by the 'Q' output of oscillator/timer
A1U4. Capacitor A1C8 and resistor A1R21 form a
differentiating circuit, that provides a positive voltage
pulse, as the output of the battery voltage comparator,
when the battery voltage decays below the reference
level and the output of A1U3D goes 'low'. A1U5-
B-5's input will be held 'high' and hold the output of
A1U5B 'low' when oscillator/timer is counting
through one of its eight second periods. This feature
prevents A1C4 from generating a positive voltage
pulse, to reset the eight second timer, once the timer
has started to count.
2.3.7 EIGHT SECOND TIMER: The eight
second timer circuit consists of oscillator/timer A1U4;
OR gate A1U5D, which is connected as an inverter;
transistor A1Q2 and their associated components.
Oscillator/timer A1U4 is an integrated circuit device
that has been connected to produce a 'high' (15 V dc)
on its 'Q' output for eight seconds after the application
of a positive voltage pulse to its master reset input. Its
'Q' output will revert to a 'low' (dc reference level),
after this eight second period and remain there until
the next application of a positive voltage pulse to its
master reset input.for eight seconds after the
application of a positive voltage pulse to its master
reset input. When the 'Q' output of A1U4 is held 'low'
(between eight second counting periods), inverting
gate A1U5D will apply a 'high' to the base of
transistor A1Q2. A1Q2 will be forward biased and
turned on. It's collector/emitter junction will be a
short circuit to the dc reference level. This short
circuit will clamp the collector of transistor A1Q1 to
the dc reference level and inhibit the operation of
transistor A1Q1. When A1U4's 'Q' output is held
'high', during the eight second counting period;
inverting gate A1U5D will apply a 'low' to the base of
transistor A1Q2. A1Q2 will be reverse biased and
turned off. It's collector/emitter junction will be an
open circuit and it will have no influence on the
operation of transistor A1Q1.
2.3.8 CHARGING CURRENT CONTROL:
The charging current control circuit consists of
operational amplifier A1U3C and its associated
components. Operational amplifier is connected as a
fixed gain, linear amplifier that has a gain factor of
approximately 100 to 1. The voltage drop across
resistor R1, as the result of the battery charging
current passing thru them, is applied to the
non-inverting input of A1U3C. Resistors A1R17/R18
form a voltage divider that applies an adjustable,
reference voltage to the inverting input of A1U3C.
Potentiometer A1R18 is adjusted, during calibration,
to provide a dc control voltage, at the output of
A1U3C, that will ultimately control the turn on time
of thyristors Q1/Q2 and maintain the charging current
to the batteries at the desired level. Capacitor A1C7
filters any ac ripple component on the output of
A1U3C and maintains its control voltage output as a
smoothed dc. If the voltage drop across R1 decreases,
the non-inverting input of A1U3C will go less
positive than its inverting input. The output of
A1U3C will go less positive and cause thyristors
Q1/Q2 to turn on earlier during each positive half
cycle applied to their anodes. If the voltage drop
across R1 increases, the non-inverting input of
A1U3C will go more positive than its inverting input.
The output of A1U3C will go more positive and cause
thyristors Q1/Q2 to turn on later during each positive
half cycle applied to their anodes.
2.3.9 THYRISTOR TURN-ON CONTROL:
The thyristor turn-on control circuit consists of
operational amplifier A1U3B, which is connected as a
comparator; transistor A1Q3, which is connected as a
switching transistor and their associated components.
The positive voltage going, linear, ramp waveform
from capacitor A1C4 is applied to the inverting input
of A1U3B, while the variable, positive, dc control
voltage from A1U3C is applied to A1U3B's non- i-
nverting input. During the period of time the linear,
ramp waveform on A1U3B's non-inverting input is
less positive than the control voltage on its inverting
input, A1U3B's output will be 'high' (23 V dc).
Transistor A1Q3 will be reverse biased and turned off.
When the linear, ramp waveform voltage goes more
positive than the control voltage, A1U3B's output will
switch to a 'low' (dc reference level). A1Q3 will be
forward biased and turned on. When A1Q3 turns on,
a positive voltage pulse is produced at the junctions of
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A1R13/R15 and A1R14/R16 as the output of the
thyristor control circuit. Since the linear ramp
waveforms occur at twice the frequency of the ac
source voltage and their dc reference starting point
coincides with the start of each half cycle of this ac
voltage, the level of the control voltage applied to
A1U3B's non-inverting input will determine when,
during each half cycle of the ac source voltage, the
positive voltage pulses will occur. Any increase in
the control voltage will cause the positive voltage
pulses to occur later, while any decrease will cause
them to occur earlier. Refer to figure 2-1 for timing
information.
2.3.10 FULL-WAVE RECTIFIER: The
switched full-wave rectifier circuit consists of
thyristors Q1/Q2, which are connected as a full- wave
rectifier; free wheeling diode CR1, inductor L1 and
the 150 volt ac, centre tapped secondary winding of
power transformer T1. The centre tap of T1's
secondary winding is connected to TB2-1, thru
inductor L1 as the negative voltage terminal for
voltages developed by the switched full-wave
rectifier. The 75-0-75 RMS ac voltage from T1's
secondary winding is applied to
the anodes of thyristors Q1 and Q2, with the anode of
each 180 degrees out of phase with the other.
Whichever thyristor has a positive voltage on its
anode will turn on when the positive voltage pulse,
from the thyristor turn-on control circuit, is applied to
their control gates. The conducting thyristor will
remain turned on until its anode goes negative.
Current pulses will be applied to the batteries being
charged each time the anode voltage of the conducting
thyristor exceeds the battery terminal voltage.
Inductor L1 and the internal capacitance of the battery
will smooth these current pulses to an average value.
The timing of the positive voltage pulses, applied to
the thyristor control gates, is controlled, as described
in paragraphs 2.3.8 and 2.3.9, to ensure they occur
during the portion of each half cycle that will maintain
the average dc current at the desired charging current
level. Freewheeling diode CR1 prevents oscillation in
inductor L1 during abrupt changes in current flow
thru L1.
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Figure 2-1 Timing Information
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