OM-200 08248 1 INSTRUCTION MANUAL for · 1997. 12. 23. · OM-200 08248 1 INSTRUCTION MANUAL for DC...

.

OM-200 08248 1

INSTRUCTION MANUAL

for

DC Voltage Regulator

Part No. 485972

Hobart Brothers Company Power Systems Division

Troy, Ohio 45373 U.S.A.

SAFETY-.INSTRUCTIONS AND WARNINGS FOR ELECTRICAL POWER EQUIPMENT .---. -- .- .llYL>.

ELECTRIC SHOCK can kill. Do not touch live electrical parts.

ELECTRIC ARC FLASH can injure eyes burn skin cause equipment damage and 1 ignite combustible material. Do not use power cables to'

/ I

.break lo,a+! and prevent tools from causing short circuits.

IMPROPER PHASE CONNECTION, PARALLELING, OR USE can damage this and attached' equipment. I

1: ' KPORTANT: - Protect all operating personnel. Read, understand and follow: all instructions in the Operating/Instruction Mar&l before installing, operating , or‘servicxng the equipment. available for future use by all operators.

Keep the manual 2

GENERAL

Equipment that supplies electrical power can'cause serious injury or death, or damage to other equipment or property. The operator must strictly I

j

observe all safety rules and take precautionary actions.. /

Safe practices have been developed from past experience in the use of power source equipment. While certain practices below apply only to electrically-powered equipment, other practices apply to engine-driven equipment,

j and some practices to;both.:

SHOCK PREVENTION i

Bare conductors, electrically-live

or terminals in the output circuit, or ungrounded, equipment can fatally shock a person.

j Have a certified

electrician verify that the equipment is adequately grounded and learn what / terminals and parts are electrically HOT. Avoid hot spots on machine. Use j proper safety clothing, procedures, and test equipment. I

The electrical resistance of the body is decreased when wet, permitting! dangerous currents to flow through it.

'.

equipment, do not work in damp areas. When inspecting or servicing Stand on a dry rubber mat or

, I

dry wood, use insulating gloves when dampness or sweat cannot be avoided. Keep clothing dry, and never work alone.

;

I 1. Installation and Grounding of Electrically Powered Equipment ' I

Equipment driven by electric motors (rather than by diesel or gasoline I

' engines) must be installed and maintained in accordance with the National! Electrical Code, ANSI/NFPA 70 and other a plicable codes. A poweri disconnect switch or circuit &eaker must. e g

i:

Check the nameplate for volta e, located at the equipment.

only 3-phase power is availab e, f frequency, and phase requirements.' If { connect any single- hase rated equipment

to only two nres of the 3-phase line. DO NOT CONNE T E the equipment I grounding conductor (lead) to the third live wire of the 3-phase line, as this makes the equipment frame electrically HOT, which can cause a fata= snoclc.- -e--p, I

Alwa s x

connect the grounding lead to t e grounded

if supplied in a power line cable swi.iEkdbox or b&ding ground.

separate groundin If not provided, usb'a i

of the grounding !z ead will Ensure that the current (am erage) be-adequate for the worst i! ault

capaci!y

situation. current ,

details. Refer to the National Electrical Code ANSI/NFPA 70 for

Do not remove plug ground prongs. Use correctly mating ; receptacles.

2. Output Cables and Terminals i

Inspect cables frequently for damage to the insulation and the I connectors. not overload

Re lace or repair cracked or worn cables immediately. IDo ca g les.

energized. Do not touch output terminal while.equipment Fs

I 3. Service and tiintenance I

L -----_----_- Instruction 910082 Feb 25/86 Revised

1 Page 1

Before inspecting or servicing electrically-powered equepment,. /' -. ;--take the--fullow$ng-precautions: ____-.------ - . .--

, .--' j I- 7/-. ~-~--a.---- Shut-OFF-;.~l-poweFat--t-h**~~nnac~~n -svi-tch-or--li/ne(breakere.-

before inspecting or servicing the equ pment. !? I

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I I I I I I I IC . I I I I I

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b. Lock switch OPEN (or remove line fuses) so that power cannot be turned ON accidentally.

c. Disconnect power to equipment if it is out of service.

d. If troubleshooting must be done with the unit ener ized, have another person presen ; ho is trained in turning o and providing or call n 13

P f for first aid.

the equipment

FIRE AND EXPLOSION PREVENTION

Fire and explosion are caused by electrical short circuits, combustible material near engine exhaust piping, misuse of batteries and fuel, or UII 23

1.

afe operating-or fueling cbnditions.

Electrical Short Circuits and Overloads

Overloaded or shorted equipment can become hot enough to cause fires either by self destruction or causing nearby combustibles to ignite. For electrically-powered equipment, in particular, input protection to remove short circuited or heavi E

rovide primary ,

equipment from the line. y overloaded

2. Batteries _

Batteries may explode and/or give off flammable hydro en and arcing from a ru failures. When ser VI

tured battery can cause fires an % ad%?$on??" acid cing, do not smoke, cause sparking, or use open

flame near the battery.

3. Engine Fuel

Use only approved fuel container or fueling system. Fires and explosions can occur if the fuel tank is not grounded prior to or during fuel transfer. completely fill

Shut unit DOWN before removing fuel tank cap. Do not tank,

expansion overflow. because heat from the a uipment may cause fuel. Remove all spilled fuel 4

that penetrates the unit. After clean-up, MMEDIATELY, includin

open equipment doors an % any blow

fumes away with compressed air.

BC -

",; ec ar

IC FUME PREVENTION I

bon monoxide.-- Engine exhaust fumes can kill and cause health problems. ; e or vent the exhaust fumes to a suitable exhaust duct or outdoors. 'er locate engine exhausts near intake ducts of air conditioners. I

1 lILY INJURY PREVENTION I I ,ious inju

x can result from contact with fans inside some equipment.' I

.t DOWN.suc I

.ipment is equipment for inspection and routine maintenance. When

in o adjustment. E

eration use extreme care in doing necessary troubleshootin o not remove guards while equipment is operating.

I lICAL AND FIRST AID TREATMENT I

I 'st aid facilities and a qualified first aid person should be available ' each shift for immediate treatment of all injury victims. Electric

f

ck victims should be checked by a ph mediately if any abnormal signs are o served. B

sician and taken to a hospital ; I 1

EMERGENCY FIRST AID i

.l physician immediately. Seek additional assistance and use First Aid i :hnlques recommended by American Red Cross until medical help arrives. ;

a Iw !e

BREATHING IS DIFFICULT g%ve oxy en, P

if available, and have victim lie FOR ELECTRICAL SHO& turn o f power. Remove victim* if not

z;hing, begin artificial'respiration preferably mouth-to-mouth. If able pulse. begin external hea& massage. Call Emergency Rescue tad immediately.

I u

f tFI-PMENlf-PR& ..- --_ is ec a p, t

L---rep ceall- beli that cannot be easily rea II geca tlonaly iaozls on the equirnt rnon~h~yI- Order and

Page 2 Instruction 910082 Revised Feb 25186

I I

OPERATION AND MAINTENANCE MANUAL OM-200 FOR D.C. VOLTAGE REGULATOR 485972

CHAPTER 1. DESCRIPTION/OPERATION

SECTION 1. DESCRIPTION

1. Genera 1 Description i 4 A. The 485972 regulator is designed to provide 2% regulation with 500

millisecond recovery time on 28.5 volt self-excited D.C. generators, 1

requiring no more than 7 amperes shunt field excitation.

The regulator controls the output voltage of the generator by switching a power transistor in series with the generator field al- ternately on and off, varying the average fie.ld power by varying the ratio of transistor on and off time. Means are also available for current limiting and line drop compensation.

B. The voltage regulator consists of ten (10) basic interconnected circuits. They are:

(1) Voltage Detection Circuit (2) Voltage C omparison Circuit (3) Summing Applifier Circuit (4) Pulse Width Modulator Circuit

12; pi;chAn; Transistor Circuit .am in ircuit

(7) Current Limit Circuit (8) Line Drop Compensator Circuit (9) Voltage Hold-Up (12V) Circuit (10) Voltage Build Up Circuit

C. Any deviation of the generator voltage from its set, regulated level is sensed by the voltage detection and voltage compa~rison

circuits. A signal is fed from the comparison circuit to the summing amplifier where the signal is modified, (if necessary) to

account for 1 ine drop compensation or current 1 imiting. This modified signal is then fed to the pulse width modulator circuit causing the output pulses driving the power transistor.fo vary in such a manner as to bring the generator voltage back to its previously set level.

D. Operating power for the above circuits is supplied by the genera-

tor output. The generator output voltage is fed to an emitter- follower regulator (consisting of 42, VR2, R3 and C7), this regulator limits the supply voltage to a safe level, acceptable to the components it powers. Two integrated ci rcui t (1 C) regu’lators (US, U6) are powered from the emitter-follower regulator. The IC’s are used where a stable, lower voltage is required.

. . PAGE 1

OPERATION AND MAINTENANCE MANUAL OM-200

FOR D.C. VOLTAGE REGULATOR 485972

2. Circuit Descriptions

A. Voltage Detection Circuit 1 ; I

This circuit consists of Capacitors C5, C9; Resistors, R13, R14; and a

Potentiometer R33. The resistors and potentiometer form a simple voltage , divider network where the voltage at the potentiometer wiper is merely a

portion of the generator output voltage. The capacitors reduce the effect of generator commutator ripple and brush arcing.

The output of the Voltage Detection Circuit is thus a filtered DC voltage p,roportional to the generator output.

B. Voltage Comparison Circuit

The voltage comparison circuit consists of a unity gain difference amplifier and constant voltage reference source.

The difference amplifier consists of Resistors R15, R18, R19, R20 and Gp

Amp Ul. The output of the difference amplifier is the signal at the non-

inverting input minus the signal at the inverting input, times the gain of the amplifier. The voltage at the inverting input is fed by a voltage divider network (R5, R34) and an 8 volt regulator source; always holding the voltage to this input constant. The voltage at the non-inverting input is the signal from the voltage detection circuit. Since the gain of :::. the amplifier is unity (set by the resistors), the output is the difference between these two input signals.

C. Summing Amplifier Circuit

The Summing Amplifier consists of Resistors R21, R22, R23, R24, R25, R26

and Op-Amp Ul. The resistors set the gain of the amplifier; unity. The output of the summing amplifier is the sum of the signals at the non-

inverting input, minus the sum of the signals at the inverting input.

The signals at the non-inverting input are the outputs of the Voltage Comparison Circuit and the Current Limiting Circuit. The signals at the inverting input are the outputs of the Line Drop Compensation Circuit and the Voltage Holdup Circuit.

The function of the Summing Amplifier is to modify the signal derived by the Voltage Comparison Circuit in such a manner as to allow the regulator

to provide line drop compensation, current limiting and voltage holdup.

D. Pulse Width Modulator Circuit

The pulse Width Modulator Circuit (PWM) is comprized of a triangle wave generator and a voltage comparator circuit.

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PAGE 2

AUG. 24/81


The triangle wave generator consists of Capacitors Cl, C2, C3; Resistors

Rll, R30; and two IC’s U3, U4. The square wave output of U3 (555 Timer) is integrated by an Inv

r

rting Hex Buffer U4 to produce the triangle wave.

Capacitor Cl sets the f equency of the triangle wave and Resistors R30

and Rli are sized to give symmetrical.rise and fal-1 times of the.wave.-’ Capacitors C2, C3 are for power supplying bypassing. This triangle wave ,

is fed to the non-inverting input (through R29) of the voltage comparator.

The voltage comparator circuit consists of Resistors R4, R16, R29 and Comparator U2. The signal at the non-inverting input is the generated triangle wave. The signal at the inverting input is the DC level voltage from the output of the Summing Amplifier. As the positive sloping edge of the triangle wave exceeds the DC level voltage, the comparator turns on. The comparator remains on until the negative sloping edge of the

triangle wave falls below the DC level voltage,turning the comparator off.

The duty cycle of the output pulse train is adjustable by increasing or

decreasing the DC level voltage. As the DC level increases, the duty cycle of the output pulses decreases.

The output of the Pulse Width Modulator Circuit is connected to the

Dar1 ington Power Transistor, 43. As the duty cycle of the PWM decreases, the average on time of the transistor decreases. Resistor R4 limits the available current to acceptable levels for U4 and the transistor.

E. Switching Transistor Circuit

The Switching Transistor Circuit consists of Diode CR1 and Darlington Power Transistor 43. Transistor Q3 is connected in series with the generator shunt fields; collector to generator field lead, emitter to generator negative.

The base drive to the transistor is supplied by the Pulse Width Modulator

Circuit. As the duty cycle of the PWM increases, the average on time of the transistor in turn increases. In this manner, varying the ‘transistor on and off times, varies the average generator field power.

Diode CR1 is a “Flyback” diode shunt across the generator exciter fields. When transistor Q3 turns off, the current through the exciter fields is maintained by flowing through the diode.

F. Damping Ci rcui t

The damping circuit consists of Capacitor C4 and Resistor R7. The damping circuit detects changes in the generator output and feeds a transient current to the Pulse Width Modulator Circuit in such a manner as to oppose

the sensed change.

The function of the Damping Circuit is to prevent oscillation and reduce

the transient response time following load changes.

AUG 24/81 l-l

_.. PAGE 3


G. Current Limit Circuit

The current limit circuit )cons’ists of a single stage transistor amplifier and a voltage comparator ci rkui t. The driving signal to the transistor

amplifier is obtained by sensing the voltage drop across the generator

interpole winding. The amplifier circuit consists of Resistors Rl, R2, R6;-: , Potentiometer R31, ~32; Capacitors ~8, C6 and Transistor Ql.

When the generator current reaches a level such that the interpole voltage

exceeds the threshold voltage of the transistors emitter-base junction, the transistor conducts. Capacitor ~8 reduces the effect of brush arcing

and commutator ripple. Resistor R6 1 imits the base current to a safe

level, as Rl, R2 and R31 limit the collector current to acceptable levels.

The voltage gain of the amplifier is controlled by Potentiometer R32.

The output voltage developed at C6 is proportional to the generator load current.

The voltage developed at ~6 is fed to the non-inverting input of the com- -- .._ parator circuit (through Ul used as a unity gain,‘hfgh impedance amplifier). The comparator circuit consists of Resistors R27, ~28, R10 and Comparator u2. A reference voltage (set by a potentiometer from the control panel) is fed to the inverting input. When the voltage ,(pr_oportional to current) ---. ____ exceeds the ~01 tage of the reference (inverting $npuc) i--t&. comparator turns on. This signal is fed to the Summing Amplifier.

Once the pre-set value of current is reached, the Current Limit Circuit

causes the regulator to decrease the generator voltage in such a manner that this value of current is not exceeded.

H. Line Drop Compensation Circuit

The Line Drop Compensation Circuit consists of Diodes CR2, CR3 and Op-Amp

Ul. A portion of the voltage developed in the transistor amplifier of the Current Limiting Circuit (wiper of R31) is fed through a unity gain amplifier (for high impedance) to the input of the Summing Amplifier. Diodes CR2, CR3 limit the maximum voltage signal from the Line .Drop

Compensator Circuit to approximately 1.4 Volts.

The Line Drop Compensator Circuit causes the regulator to increase the generator voltage with load such that the voltage at the load end of the generator output cables remains constant despite the load cable voltage

drop.

I. Voltage Hold-Up Circuit

The Voltage Hold-Up Circuit consists of Resistors, R8, R9, R12, R17; Diode VRl and Comparator U2.

The Non-inverting input of the comparator is held constant by Zener Diode VRl. Resistor R12 limits the current to the diode to safe levels.

-‘l-l AUG 24-181 - . .-..-

-PAGE 4 ‘. ..^



Resistors R8, R17 form a voltage divider network across the 27V regu-

lator ci rcui t. This portion of voltage is fed to the inverting input. As the generator vol tagjeiIfalls towards zero, the regulated-. -27V fol lows the generator voltage. When the generator voltage fall s to approximately 12V, the comparator turns on. Resistor R27 is sized to limit the current through the comparator to a safe level. When the comparator t turns on, the signal is fed to the Summing Amplifier.

The function of the Voltage Hold-Up Circuit is to limit the voltage to which the generator can fall when in the current limit mode. Should the voltage fall below 12 volts, the output contactor.would open, de-ener- gizing the load.

J. Voltage Build-Up Circuit

The Voltage Build-Up Circuit consists of Relay Kl, Capacitor Cl0 and Voltage Regulator ~6. When the generator is rotating at or near normal operating speed, voltage build up begins from residual magnetism. This -*- residual voltage biases the transistor full on. This causes full generator voltage to be applied to the shunt field and the resulting self excitation increases the generator voltage. ~6 reaches the pull-in voltage of the relay,

When the output voltage of the contacts open al lowing.5+s--

the regulator to assume the controlling operation.

AUG 24/81 l-l

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PAGE 6

AUG 24/81

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SECTION 2. ADJUSTMENTS

1. General

i 4 There are three multi-turn potentiometers and one single turn potentiometer which are factory set for proper generator operating characteristics.

Should re-adjustment become necessary, please refer to the following:

A. 28.5 Volt Adjustment

The regulating voltage in the 28.5 volt range is determined by the position of the wiper arm of the Potentiometer R33, clockwise (CW) rotation decreases the voltage level that the unit operates. Con- versely counterclockwise (CCW) rotation increases the voltage level. Any adjustment of this potentiometer will affect the operation of the

14 Volt range (if supplied).

B. 14 Volt Adjustment

The adjustment of the potentiometer, R34, should be made only after the 28.5 Volt range has been set. optional 14 volt output,

If the unit is equipped with the set the -vo&$ge range switch in the 14 Volt

position. Clockwise rotation decreases the voltage level, counterclockwise increases the voltage level.

Adjustment of this potentiometer will not affect the 28.5 Volt regulating range.

C. Line Drop Compensation

Line drop compensation allows the voltage at the load end of the output cable to remain constant despite the voltage drop associated with

the output cable. Clockwise rotation of the line drop compensation Potentiometer R31, increases compensation. This- potentiometer should be set for flat regulation of voltage at the load end when delivering rated load current.

D. Current Limiting

The current limiting Potentiometer R32, must be adjusted in conjunction with the current limiting rheostat located on the control panel of the

unit. Set the dial on the current limiting rheostat to 600 amps. With

a loadbank, apply 800A-900A load. Clockwise rotation-of R32 wi 11 cause output current to fall off. Counterclockwise rotation will cause output current to rise. Potentiometer R32 should be adjusted such that the

1 rheostat. output current matches the dia

This adjustment is factory set

in the field.

1 setting of the front pane

and should not normally need adjusting

AUG 24/81 l-2

PAGE 1



l-2

PAGE 2

AUG 24;81


SECTION 3. TROUBLESHOOTING

1. Genera 1 i 4

Troubleshooting is an orderly process of checking and eliminating possible causes of trouble until the exact cause of a trouble is found.

2. Troubleshooting Chart

The troubleshooting chart lists information in the following manner:

Trouble Possible Cause

Remedy

The information contained in the following list is not all possible causes of failures. If the cause of a trouble is an uncommon one and cannot be located by use of the list, the individual circuits must be completely checked.

A. Generator voltage wi 11 not bui Id up to normal.

(I) Voltage b ui Id-up circuit relay (Kl) normally closed contacts open. Replace relay.

(2) Generator residual voltage too low. Flash exciter fields with “Push To Bui Id Up Voltage” switch.

B. Generator voltage builds up until relay actuates; then fa.lls back. (1) Integrated circuit U4 failed. Replace U4. (2) Integrated circuit U3 failed. Replace U3.

C. Generator voltage builds up to dangerously high levels. Flashing

relay (Kl) does not actuate. (1) Voltage regulator U6 failed. Replace ~6. (2) Relay Kl defective. Replace Kl. .(3) Capacitor Cl0 shorted. Replace ClO.

D. Generator voltage builds up to a dangerously high level; flashing relay (Kl) actuates, but voltage is not controllable with voltage adjusting potentiometer R33.

(1) Transistor 43 shorted. Replace 43. (2) Integrated Circuit Ul fai led. Replace Ul .-‘y (3) Integrated circuit U2 fai led. Replace U2. (4) Capacitor C5 shorted. Replace C5. (5) Voltage comparison potentiometer R33 open. Replace R33.

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AUG 24/8f -

PAGE 1

I I OPERATION AND MAINTENANCE MANUAL OM-200


E. Generator voltage is unstable, oscillates.

(1) Capacitor C4 shorted.'! Replace C4. (2) Capacitor Cg open. Repl'ace Cg.

F. Generator voltage falls off when load is applied.

(1) Transistor Ql shorted. Replace Ql.

(2) Current limit rheostat (front panel) shorted. Replace rheostat.

PAGE 2

AUG 24181

Cover OM-200Safety Warnings and Cautions1-1 Description/Operation1-2 Adjustments1-3 Troubleshooting

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