SE_NONE_350-05002-00_INSTRUCTION_MANUAL_KATO_PILOT_EXCITERS_(PERMANENT_MAGNET_GENERATORS)_(1)_0001.pdf

INSTRUCTION MANUAL

Kato Engineering P.O. Box 8447 Mankato, MN 56002-8447 ( 507) 625-4011

SERIAL NUMBER

10965

RELIANCE ..

ELECTR/c•o

Publication Number: 350-05002-00 Publication Date: August 1985

BEARING LUBRICATION INSTRUCTIONS

For Common Frame MG Sets

SERIAL NUMBER MODEL NUMBER TYPE NUMBER

~---l-09_6_s ___ __,f Gen.\'--__ K_2_4_96_2_0_0_0_1 __ _____.I ._I ____ 24_9_6_2 ___ __J

Grease ~--Fitting

Grease Relief Valve

Motor I

HO RIZO NT AL MG

IN COMMON WITH GE~ERA~._O_R _______ __,

/Grease / Fitting

Grease Relief Valve

Grease ~ Grease Fitting Relief '===1

Bearing

Grease Relief Valve

Top 1 •

.,Bearing/ , ' I

:I

Lower Be~ring

Grease

VERTICAL MG Fitting

Where grease fittings and grease relief valve are mounted into bearing housing, remove cover from exciter end of unit for access to fittings.

Replenish grease in bearings using the amounts of grease listed below and at intervals shown in running time hours or months, whichever occurs first. Do not overfill. Wipe excess grease from internal parts of unit.

Use a high quality NLGI Grade 2 electric motor bearing grease which will lubricate satisfactorily over a range from lowest ambient temperature expected to + 250F.

GENERATOR OR LOWER MOTOR OR TOP

Bearing Number

012-21172-00 012-21172-00

Replenish Interval in Running Time Hours

2800 2800

Replenish Interval in Months

12 12

Replenish Amount in Ounces

1.8 1.8

Publication Number: 350-01003-00 Publication Date: January 19n

INSTRUCTION MANUAL

KATO PILOT EXCITERS

(Permanent Magnet Generators)

...._. Kato Engineering P.O. Box 8447 Mankato, MN 56002-8447 U.S.A.

(507) 625-4011 I FAX (507) 345-2798

Telex 29-0786 C.P.O. 390

ELECTR1c•o

TABLE OF CONTENTS

SECTION PAGE

INTRODUCTION

II APPLICATION CONSIDERATIONS

111 TYPICAL APPLICATIONS

PMG as power source for voltage regulator PMG used for field flashing PMG as power source for de motor speed control PMG as power source for de generator voltage regulator

IV MAINTENANCE

General precautions General procedure for disassembly and <issembly of PMG

Permanent Magnet Generator Fie.:....----.

Cover for Permanent Magnet Gen. & Exciter Assy.

Exciter Field

Permanent Magnet Generator Armature

Exciter Armature & --Rotating Rectifier Assy.

...__ __ Retaining Bolt

Brushless Generator

Figure 1 Typical brushless generator with a permanent magnet generator (Pilot Exciter) used to supply field flashing or voltage regulator power.

350-01003-00

Permanent Maqnet Generator Armature

Permanent Magnet Generator Field

'-----Retaining Bolt

Covet for -""'--- Permanet

Magnet Generator

Figure 2 Typical KATO static excited ac generator with field flashing form a permanent magnet generator (Pilot Exciter).

INTRODUCTION

A permanent magnet generator (PMG) is installed as a modif ication in certain Kato generators. It delivers either 120 or 240 volt single phase ac. It functions as a pilot exciter, fur nishing power to the voltage regulator. Its output can be rectified and used for field flashing. It can be also used for any purpose where 120 or 240 volts ac is required and no other source is readily available.

The PMG is basically a revolving field single-phase ac gen erator. Its distinctive feature is the use of permanent magnets instead of electromagnets to provide the magnetic field. As in a conventional ac generator, voltage js induced in the st ationary armature when the magnetic field is rotated inside it.

When installed on a generator, the PMG stator is bolted to the endbell opposite the drive end either by itself (Figure 2) or as part of a larger assembly that includes the exciter field (Fig ure 1 ). The stator consists of armature windings in a laminat ed core which is welded to a steel frame.

The permanet magnets and soft pole tips of the revolving field are permanently attached to a steel hub by non-magnetic stainless steel bolts. The field is magnetized after the rotor is ssembled and the permanent magnet material has been per

~nanently secured in place in the magnetic circuit.

11 APPLICATION CONSIDERATIONS

Several features of the PMG make it valuable as a pilot exciter.

The first is that it requires no other current source to initiate its own voltage buildup. The advantage of the PMG in this respect is seen when it is compared with a generator using an electromagnetic field. Such a generator must rely on residual magnetism in the field core to initiate voltage buildup when it is started. The field core, not being made of permanet magnet material, retains a comparatively low and variable degree of magnetism from the previous period of operation. This re sidual magnetism may be too low to build up voltage when the generator is started, in which case the field must be flashed, that is, given an initial exciting current from an ouside source.

The PMG on the other hand can provide positive voltage build up - - - it will develop its rated output voltage provided only that it is driven at rated speed. It can therfore be used to pro vide flashing current for the exciter of the generator to which it is attached.

A second valuable feature of the PMG is that it provides a voltage source that is independent of the terminal voltage of its associated generator. If the PMG is used to power the voltage regulator, full voltage and power will be available for excitation even during heavy transients or short circuit con ditions.

A third advantage of the PMG is that its terminal voltage is designed to power the voltage regulator when driven at rated speed. This makes unnecessary the transformer that would otherwise be required if the generator output did not match the input voltage of the regulator.

A fourth advantage of the PMG results from its allowing the power output stage of the voltage regulator to be isolated from the generator output. Without a PMG, where the voltage regulator takes its power from the generator output, high fre quency interference resulting from switching transients in the voltage regulator output stage could be conducted to the load unless special filtering or isolation was previded.

Ill TYPICAL APPLICATIONS

In the following paragraphs, several applications of PMG's are briefly described. This material is presented for the pur pose of discussion only and should not be used for making electrical connections.

PMG AS POWER SOURCE FOR VOLTAGE REGULATOR

Figure 1 shows the general contruction and location of a PMG on a brushless ac generator. The armature of the PMG and the field of the brushless exciter are built into the same frame.

In another design not shown, these two components are sep arate. In yet another design, the exciter field is mounted in board of the bearing and endbell, and the PMG armature only is on the outboard side. In any case, the electrical shematic will resemble Figure 3.

The PMG delivers rated ac voltage to the regulator. The reg ulator, using power supplied by the PMG, energizes the exciter field. The theory of the generator and voltage regulator is the same as that described in Publication 350-01001-00 with the exception that the voltage regulator derives power from the PMG instead of the generator output.

During those periods when high current is drawn from the generator, such as during the transients caused by motor start ing or during short circuit conditions, the generator output voltage will be lowered and the current requirement of the exciter field will be raised. In an istallation where the voltage regulator receives its power from the generator output, this combination of decreased input voltage and increased output requirement may bring about collapse of generator output voltage, unless special series boost provisions are made for these circumstances.

However, in those installations where the voltage regulator is powered by a PMG, voltage and power for excitation are un affected by the drop in output voltage. Full exciter power is available for motor starting and for short circuit fault clearance.

350-01003-00

VOLTAGE REGULATOR

a: a:

0 ...

~~a: ... "' ~ "' w ::::> ~;: "'"' ffi - ~ ill 0 a: a:

AC AC F1 F2

PERMANENT

MAGNET

GENERATOR

a:

0" ... z

"'15 ill"' a:

ROTATING BRUSHLESS

EXCITER ARMATURE

AND RECTIFIERS

TO LOAD

GENERATOR

STATOR

Figure 3 PMG supplying power to voltage regulator on brushless ac generator.

STATIONARY

RECTIFIER

BRIDGE

STATIC EXCITER-REGULATOR

I I

VOLTAGE

ADJUST TO LOAD

PERMANENT

MAGNET

GENERATOR ROTATING FIELD

GENERATOR

STATOR

Figure 4 PMG used for field flashing on static excited ac generator.

PMG USED FOR FIELD FLASHING

Where positive voltage buildup is required but separate battery or rectified ac flashing sources are not easily available, a PMG can be used to advantage. It may be installed on either a brushless generator or a static excited generator. ~

A typical simplified schematic of an installation with a static exciter is shown in Figure 4. The physical location of a PMG on a static excited generator is shown in Figure 2. The rec tified output of the PMG is applied to the field through the normally closed contacts of a relay in the static exciter.

When the generator output voltage builds up to sufficient level, it actuates the relay, transferring the generator field to the static exciter. A separate relay can be wired into the circuit with a static exciter that does not include one.

PM

...J"' 0 z ~ 0 z !:

8 ;:

AC POWER TO

REGULATOR

PERMANENT MAGNET GENERATOR

SENSING VOLTAGE

TACHOMETER

ct

:J

"' w ct w w 0..

Figure 5 PMG used to power speed regulator for shunt or compound de motor.

PMG AS POWER SOURCE FOR DC MOTOR SPEED CONTROL

A PMG can be mounted on a de motor to provide ac power for speed control circuitry. A possible application is sketched in Figure 5. In this example, the strength of the flux field, and hence the motor speed, depends on the combined action of the shunt field and control winding. De current in the control winding is varied by the speed regulator. Sensing volt age is obtained from a tachometer; in other designs, a mec· hanical governor is used to provide a control signal. The regulator circuitry is powered by ac from the PMG.

PMG AS POWER SOURCE FOR DC GENERATOR

VOLTAGE REGULATOR

A PMG can be mounted on a de generator to provide ac power for the generator voltage regulator circuitry. A possible application is sketched in Figure 6. In this example the volt age regulator, powered by the PMG, senses the de output of the generator and regulates the generator field current to keep the generator output at rated voltage.

VOLTAGE REGULATOR

PERMANENT MAGNET

GENERATOR

...J w ii:

ct ct w z w

"' g g

SENSING VOLTAGE

TO REGULATOR

0 C GENERATOR

g g u

Figure 6 PMG used as power source for voltage regulator on a de generator .

IV MAINTENANCE

GENERAL PRECAUTIONS

Since there are no bearings, brushes or sliprings and no semi· conductor devices, maintenance is minimal. The unit should be kept clean and the vents should be kept open. Keep iron and steel debris away from the rotor.

No attempt should be made to unbolt and separate the parts of the rotor. Breaking the magnetic circuit would alter the permanent magnets, reducing their strength. Reassembling the rotor would not restore the magnetism to its prior state.

Avoid exposing the rotor to excessive heat or mechanical shock. If the rotor is removed and is to remain out of the machine for an extended period, a steel or iron strap or band may be wrapped around the periphery of the rotor to act as a keeper.

If the endbell on the end oppsite the PMG is removed, make sure that the movement of the shaft does not force the PMG rotor against the stator. Note that the air gap in the PMG is considerably smaller than that in a large generator. It may be necessary to remove the PMG rotor when working on the drive end bearing.

WARNING

USE EXTRA CARE WHEN REMOVING ROTOR

TO PREVENT INJURY TO HANDS DUE TO

MAGNETIC ATTRACTION BETWEEN THE

PMG ROTOR AND THE PMG STATOR OR

GENERATOR SHAFT.

GENERAL PROCEDURE FOR DISASSEMBLY AND

ASSEMBLY OF PMG

When disassembling the PMG from the generator or motor, it will be advantageous to remove the rotor first.

To remove the rotor:

1. Take out the retaining bolt and washer. Read

WARNING in general precautions section before removing PMG rotor.

2. Remove the rotor.

3. If the PMG is to remain disassembled for an ex tended period, install a keeper on the rotor. Use a band of iron or steel.

4. In some designs, the exciter armature and rotat ing rectifier assembly can also be removed at this time.

To remove the stator:

1. Support the stator form an overhead crane or hoist.

350-01003-00

2. Disconnect the PMG armature leads in the con nection box. Remove any ties holding the leads to the generator frame.

3. If the exciter field is part of the same assembly as the PMG stator, repeat step 2 for the ex citer field.

4. If the rotor has not been taken off first, place thin sheets of insulating material in the air gap betweeen the rotor and stator to keep them from being forcibly attracted to each other and im peding the disassembly.

5. Remove the bolts holding the stator frame to the end bell.

6. Carefully remove the stator frame.

To assemble, reverse steps given in removal procedure.

Page 6 (blank)

Kato Engineering P.O. Box 8447 Mankato, MN 56002-8447 U.S.A.

(507) 625-4011 I FAX (507) 345-2798

Telex 29-0786 C.P.O. 390 Pnnted m U.$.A

RELIANCE ..

Fonn #350-01003-00

Publication Number: 351-01002-00A Publication Date: August 1991

Supersedes Publication Number 351-01002-00

INSTRUCTION MANUAL

KATO™ KCR 760

VOLTAGE REGULATOR

INCLUDES

PRINCIPLES OF OPERATION

INSTALLATION INSTRUCTIONS

ADJUSTMENT AND OPERATING INSTRUCTIONS

MAINTENANCE AND TROUBLESHOOTING

DRAWINGS AND GENERAL INFORMATION

Kato Engineering _.. P.O. Box 8447

Mankato, MN 56002-8447 U.S.A.

(507) 625-4011 I FAX (507) 345-2798

TELEX 29-0786 C.P.O. 390

351-01002-00A

Safety Summary

Observe the safety precautions that follow and the instructions contained in this manual when installing, operating, testing and making repairs to this equipment.

WARNING

De-energize generator set starting circuit before making repairs, connecting test instruments or removing or making connections to or within the voltage regulator. Dangerous voltages are present at the voltage regulator terminal board and within the voltage regulator when the generator set is running. These include the sensing voltage, power to the voltage regulator and the voltage regulator output. Accidental contact with live conductors could result in serious electrical shock or electrocution.

CAUTION

Regulator sensing circuit must never be opened while power is applied to the regulator input power terminals.

Loss of sensing voltage will result in maximum regulator output.

The voltage regulator de output (terminals F+ and F-) must never be opened during operation. To do so will produce inductive arcing that could destroy the exciter or voltage regulator. Therefore, never place circuit breaker contacts or voltage shutdown switch in the exciter field circuit.

CAUTION

Megger or high potential test equipment must not be used when testing the voltage regulator. Disconnect interconnecting conductors between the generator and voltage regulator when testing generator or exciter with megger or high potential test equipment. The high voltage developed by megger or high potential test equipment will destroy the solid state components within the voltage regulator.

Section 1 General Information, Specifications and Application

GENERAL

APPLICATION

STANDARD FEATURES, OPTIONS AND ACCESSORIES

A. Sensing

B. Regulator Input Power and de Output

C. Field Flashing

D. Voltage Regulator Fuse

E. Voltage Adjustment

F. Parallel Operation Components

G. Electromagnetic Interference Filters

H. Input Power Load Isolation and Voltage Matching Transformers

I. Field Circuit Breaker

J. Voltage Shutdown Switch

K. Automatic/Manual Voltage Control

SPECIFICATIONS

A. Power Output

B. Input Power

C. Sensing

D. Voltage Adjustment Range

E. Field Resistance

F. Burden Resistance

G. Paralleling

H. Fuse

I. Underfrequency Protection

J. Regulator Accuracy

K. Regulator Response

L. Thermal Stability

M. Operating Temperature

N. Storage Temperature

0. Power Dissipation

P. Shock

Q. Vibration

R. Construction

S. Dimensions

T. Weight

U. Mounting

351-01002-00A

1-1

1-1

1-1

1-1

1-1

1-1

1-1

1-2

1-2

1-2

1-2

1-2

1-2

1-2

1-2

1-2

1-3

1-3

1-3

1-3

1-3

1-3

1-3

1-3

1-3

1-3

1-3

1-3

1-3

1-3

1-3

1-4 1-4 1-4 1-4

351-01002-00A TABLE OF CONTENTS

Section 2 Principles of Operation

GENERAL

VOLTAGE REGULATOR CIRCUITS

A. Sensing Circuit During Single Generator Operation B. Sensing Circuit During Parallel Operation in Reactive Voltage Droop Compensation Mode C. Sensing Circuit During Parallel Operation in Parallel Cross-Current Compensation Mode

D. Error Detector E. Phase Control Circuit

F. Power Stage G. Field Flashing Circuit H. Stability Circuit

I. Underfrequency Limit (UFL)

MOUNTING

INTERCONNECTION

A. Single Phase 100-600 V ac Sensing B. Three Phase 100-600 V ac Sensing

C. Input Power D. Output Power

E. Grounding

F. External Voltage Adjust Rheostat

Section 3 Installation

G. Connection to Parallel Operation Reactive Voltage Droop Terminals H. UFL Circuit 50/60 and 400 Hz Selector J1 I. Voltage Regulator Fuse

ACCESSORY ITEMS

A. Voltage Shutdown (Engine Idle) Switch B. Field Circuit Breaker C. Auto/Manual Voltage Control

Section 4 Controls Adjustment and Operating Procedure

GENERAL

ADJUSTMENTS

A. Generator Voltage Adjust Rheostat (VAR) B. Nominal Voltage Range Set Adjust (R2) C. Stability Adjustment (R6) D. Parallel Voltage Droop Potentiometer (R4) E. Underfrequency Adjustment (R55)

F. Manual Voltage Control Variac

FIELD FLASHING

SINGLE UNIT INITIAL OPERATION PROCEDURE

A. Automatic Mode Operation B. Manual Mode Operation ii

2-1 2-1

2-1 2-1 2-2

2-2

2-2 2-3 2-3 2-3

2-3

3-1

3-1 3-1

3-1 3-2 3-2

3-2

3-2 3-2 3-3 3-3

3-3

3-4 3-4 3-4

4-1 4-1 4-1 4-1 4-1 4-1 4-2

4-2 4-3 4-3 4-3 4-4

PARALLEL OPERATION

A. Metering B. Checks Prior to Initial Parallel Operation C. Preliminary Parallel Operation D. Paralleling Generators E. Shutting Down One or More Generators Operating Parallel

Section 5

351-01002-00A

4-5 4-5 4-5 4-5 4-6 4-7

Maintenance, Troubleshooting and Voltage Regulator Operational Test

PREVENTIVE MAINTENANCE 5-1

CORRECTIVE MAINTENANCE 5-1

TROUBLESHOOTING 5-1

TROUBLESHOOTING CHART 5-2

VOLTAGE REGULATOR OPERATIONAL TEST 5-7

Section 6 Drawings and Parts List

Figure 1 KCR 760 Outline Drawing 6-1 Figure 2 Typical Voltage Regulator - Generator Interconnection 6-2 Figure 3 Single Phase KCR 760 Voltage Rgulator Electrical Schematic 6-3 Figure 4 Three Phase KCR 760 Voltage Regulator Electrical Schematic 6-4 Figure 5 Circuit Board Schematic: KCR 760 Voltage Regulator with UFL or Volts-Per-Hertz Circuitry 6-5 Figure 6 Circuit Board Schematic: KCR 760 Voltage Regulator with Flat Regulation Option 6-6 Figure 7 Underfrequency Limit or Volts-Per-Hertz Circuitry 6-7 Figure 8 Interconnection Diagram: Parallel Voltage Droop 6-8 Figure 9 Interconnection Diagram: Cross-Current Compensation 6-9 Figure 10 KCR 760 Operational Test 6-1 O

Figure 11 Effect of Timed Gating Signal on SCA Phase Angle 6-11 Figure 12 Standard U FL Operational Threshold 6-11 Replacement Parts List 6-12 iii

L

GENERAL

SECTION 1

GENERAL INFORMATION,

SPECIFICATIONS AND APPLICATION

351-01002-00A

The KCR 760 voltage regulator consists of transformers, transistors, silicon diodes, silicon controlled rectifiers (SCR's), integrated circuits, resistors, and capacitors. The regulators are relatively unaffected by humidity, temperature, vibration, or shock and are not subject to wear from moving parts. Solid state field flashing components rather than relays are used in the field flashing and underfreq uency circuits, eliminating the possibility of contact arcing or contact failure.

APPLICATION

The KCR 760 voltage regulator is designed for operation with brush less synchronous generators. The voltage regulator controls generator voltage by regulating the amount of current it supplies the exciter field.

STANDARD FEATURES, OPTIONS AND ACCESSORIES

Features provided in standard KCR 760 voltage regulators, options available in this series, and various accessories that can be supplied with the generator set voltage regulating system are described in the paragraphs that follow. Where options are specified in the purchase order, the required circuitry changes are made within the regulator at the factory while accessories are parts that mount external to the regulator.

A. Sensing

1. Standard Sensing The basic KCR 760 regulator utilizes single phase 50/60 Hz sensing. The sensing transformer has a multi-tap primary permitting operation at sensing voltages of 100 to 600 V ac. The standard regulator includes an underfrequency limit circuit that decreases voltage in proportion to the decrease in frequency when speed drops below the UFL operational threshold. The UFL in standard 50/60 Hz sensing regulators is adjusted with an operational threshold of 48 Hz for 50 Hz application and 58 Hz for 60 Hz application.

2. Optional Sensing When specified in the purchase order the regulator can be supplied with the following variations in sensing circuitry.

a. Three phase 50/60 Hz, 100-600 V ac sensing.

b. UFL set 49.5/59.5 Hz for use with turbocharged engines.

c. Volts-per-hertz circuitry in place of UFL for applications where voltage must be proportional to frequency over a speed range from rated rpm down to approximately 112 rated speed.

d. 400 Hz, single or three phase, 100-600 V ac with 385 Hz UFL operational threshold.

e. 400 Hz with UFL threshold higher or lower than 385 Hz.

f. 50/60 Hz or 400 Hz, single or three phase 100-600 V ac with flat regulation for motor-generator set or variable frequency/constant voltage applications. Regulators with flat regulation will not include UFL or V/Hz circuitry.

B. Regulator Input Power and de Output

1. Standard Input Power and de Output

Standard KCR 760 regulator utilizes single phase, 120 V ac.:!:.10% input power and has rated maximum continuous output of 65 V de, 10 A; 90 V de, 15 A one-minute field forcing.

2. Optional Input Power and de Output When specified in the purchase order, the KCR 760 regulator may be modified to operate from single phase, 240Vac~10% input power and thereby have rated maximum continuous output of 125 V de, 10 A; 180 V de, 15 A one-minute field forcing.

C. Field Flashing KCR 760 voltage regulators include solid state field flashing circuitry.

D. Voltage Regulator Fuse

1. Standard Fuse

Standard KCR 760 regulators are supplied with a 15 A normal blow fuse in the input power circuitry within the regulator. This fuse provides voltage regulator overload protection.

1-1

2. Optional Fuse In applications where the system does not include a field circuit breaker and generator field protection. '\ ·.

is required, a smaller fuse may be used. For generator field protection, fuse amperage should be 1 % to 2 ..J times the exciter field current with rated load connected to the generator. Fuse amperage must not exceed 15 ampere or 2/3 open circuit forcing. Fuse must be normal blow type. Do not install time delay type fuse.

E. Voltage Adjustment

1. Standard Voltage Adjust

KCR 760 voltage regulators are provided with an internal voltage range adjust potentiometer and an auto voltage adjust rheostat for remote mounting. The auto voltage adjust rheostat permits adjustment of generator voltage approximately.!.. 10% from the nominal sensing voltage.

2. Wide Range Voltage Adjust For applications where voltage must be adjusted more than ::.10% from nominal, wide range voltage adjust circuitry can be provided with the generator set. This accessory is designed for remote mounting and is electrically connected between the generator sensing lines and the regulator sensing terminals.

F. Parallel Operation Components KCR 760 voltage regulators include a parallel operation reactive voltage droop transformer (T3) and a parallel voltage droop potentiometer (R4). For parallel operation each generator must be equipped with a current transformer for sensing reactive current. The transformer may have either a 1 A or 5 A secondary.

Where 1 A current transformer is used, the secondary leads connect to regulator terminals CT• and CT1.

Where a 5 A current transformer is used, the secondary connects to regulator terminals CT• and CT5.

G. Electromagnetic Interference Fiiters When specified in the purchase order the KCR 760 regulator can be supplied with EM I filters as an external accessory.

H. Input Power Load Isolation or Voltage Matching Transformers Load isolation and voltage matching transformers are accessory items that mount external to the voltage regulator.

Load isolation transformers are available with 120 V primary, 120 V secondary (for use with standard 120 V ac input power voltage regulators), or 240 V ac primary and 240 V ac secondary (for use with 240 V ac input power regulators).

Load isolation transformers are recommended for any application where frequency of the input power to the regulator is different from the sensing frequency, such as 400 Hz motor-generator applications where regulator input power is taken from 50/60 Hz motor-generator set input power lines.

Voltage matching transformers are available for applications where available voltage is different from the voltage regulator rated input voltage.

I. Field Circuit Breaker When specified in the purchase order, the generating system can be provided with a field circuit breaker for generator field protection.

J. Voltage Shutdown Switch When specified in the purchase order, the generating system can be supplied with a switch that electrically connects in the line that supplies input power to the regulator. This protective device is recommended for engine driven generator applications not provided with field circuit breaker or underfrequency protection.

K. Automatic/Manual Voltage Control When specified in the purchase order, the generating system can be supplied with an automatic/manual voltage control module. This accessory includes a full wave rectifier and a variable transformer (variac) for manual voltage control and a three position switch. The switch allows the generator to be controlled either automatically by the voltage regulator or manually. The OFF position provides voltage shut-down by de-energizing both the voltage regulator and the manual voltage control rectifier.

SPECIFICATIONS

A. Power Output:

65 V de, 10 amperes, maximum continuous output; 90 V de, 15 A one-minute field forcing where regulator is constructed for 120 V ac input.

125 V de, 10 amperes, maximum continuous output; 180 V de, 15 A one-minute field forcing where regulator is constructed for 240 V ac input.

1-2

B. Input Power:

Single phase, 50/60 Hz, 120 V ac ± 10%; or single phase, 50/60 Hz, 240 V ac ± 10%.

NOTE: Specify regulator input and regulator power output requirement in purchase order.

Input frequency other than 50/60 Hz must be specified on the purchase order.

C.Sensing:

Standard regulators are constructed for single phase 100 V ac to 600 V ac sensing.

Three phase 100 V ac to 600 V ac available as optional feature.

Special voltage or frequency available as optional feature.

V/Hz sensing ava_ilable as optional feature.

D. Voltage Adjustment Range:

.!.10% Standard. Wide range voltage adjust available as an optional accessory.

E. Field Resistance:

6.5 n minimum; 100 n maximum for standard 65 V de regulator. 12.5 n minimum; 200 n maximum for optional 125 V de regulator.

F. Burden Resistance:

Sensing: 6 VA maximum. Input power: 2400 VA maximum for240 Vac input; 1200 VA maximum for 120 Vac input. Paralleling: 10 VA maximum.

G. Parallellng:

1 A for6% droop or 5 A for6% droop on current transformer. For 1 A connect to terminals CT• common and CT1; for 5 A connect to terminal CT• common and CT5. Factory adjusted 4% droop.

H.Fuse:

15 A maximum, ABC type fuse for voltage regulator protection.

I. Underfrequency Protection:

Except where flat regulation, V/Hz sensing or UFL with special operational threshold is specified in the purchase order, the underfrequency limit (UFL) circuit will provide underfrequency protection by reducing voltage in proportion to frequency. The UFL operational threshold where limiting starts is as follows:

1. Standard 58 Hz for 60 Hz system 48 Hz for 50 Hz system 385 Hz for 400 Hz system

2. Optional for use with generator driven by turbocharged engine

59.5 Hz for 60 Hz system

49.5 Hz for 50 Hz system

395 Hz for 400 Hz system

J. Regulator Accuracy:

Voltage regulation is maintained within~ 1/2 percent over full range of generator loading and for generator speed variations of up to 5 percent.

K. Regulator Response:

Less than 17 milliseconds.

L. Thermal Stability:

Less than.:!: Y2 percent for 40° change in ambient temperature.

M.Operatlng Temperature:

-40°C to +60°C.

N. Storage Temperature:

-60°C to +85°C.

0. Power Dissipation:

Less than 35 W at maximum continuous rating during single generator operation; less than 45 W at maximum continuous rating during parallel generator operation.

P. Shock:

Tested to withstand up to 20 g's in each axis.

1-3

Q. Vibration:

Tested to withstand 1.2 g's from 6 to 26 Hz; 0.32 in. double amplitude from 26 to 52 Hz; 5 g's from 53 to 150 Hz.

R. Construction:

Steel chassis with welded seams; zinc plated according to specification QQ-2-325, Type 11, Class 2; circuit board is silicon resin conformal coated.

S. Olmenslons:

111/2 in. (292 millimeters) x a112 in. (216 millimeters) x 43/4 in. (121 millimeters).

T. Weight:

13 pounds (5.9 kilograms).

U. Mounting:

Voltage regulator may be mounted in any position providing that sufficient space is retained about the unit for satisfactory cooling, and shock and vibration do not exceed regulator specifications.

SECTION 2

PRINCIPLES OF OPERATION

351-01002-00A

Parts comprising the KCR 760 voltage regulator are shown on the electrical schematics contained in Section 6 in this manual.

A standard single phase sensing KCR 760 voltage regulator with underfrequency limit or V/Hz sensing circuitry is described in the paragraphs that follow. Where regulator has either three phase sensing or is designed for flat regulation the following difference will apply.

1. Three phase sensing Where the three phase sensing option is included the regulator will have two sensing transformers (T1 and T3) with interconnected primary windings and interconnected secondary winding.

2. Flat Regulation Where regulator is designed for flat regulation the regulator will not have the UFL or V/Hz circuitry and the voltage applied to the reference side of the first stage differential amplifier in the error detector will be the voltage across Zener diode Z1.

VOLTAGE REGULATOR CIRCUITS

The voltage regulator senses the generator voltage, compares a rectified sample of that voltage with a reference voltage and supplies the field current required to maintain the predetermined ratio between the generator voltage and the reference voltage. Transformer T1 is the sensing transformer in a standard single phase sensing KCR 760 voltage regulator while a KCR 760 voltage regulator designed forthree phase sensing includes two sensing transformers (T1 and T3). The sensing circuitry also includes a transformer (T2) and potentiometer (R4). Transformer T2, potentiometer R4, and an external current transformer provide means of attaining reactive kVA load sharing during parallel generator operation. The parallel operation components do not affect voltage regulator operation when the generator is operated singly.

On regulators equipped with underfrequency limit (UFL) or V/Hz option, this circuitry interacts with the regulator sensing and error detector in a manner that decreases voltage during underspeed operation. A solid state flashing circuit operates each time the generator is started. The flashing circuit de-energizes when generator voltage has built up to about 70 percent of rated voltage output. Most of the circuits are contained on a printed circuit board. Parts that are individually mounted on the regulator case are the sensing transformer(s), parallel operation transformer T2, parallel voltage droop potentiometer R4, the power stage, and a fuse. External voltage adjust rheostat VAR is provided for installation on a control panel.

A. Sensing Circuit During Single Generator Operation

The voltage sensing transformer(s) provides a voltage proportional to the generator voltage output. This voltage is fed across the primary of T2 to a full wave rectifier comprised of si Ii con diodes 03, 04, 017, 018, 023, and 024. The rectified voltage is filtered by resistor R3, choke L 1 and capacitor C1. The de signal from the filter is applied to the error detector and the underfrequency limit.

Shorting the secondary parallel operation transformer T2, either by using the jumper bar across CT• and CT1, or turning R4 to its full counterclockwise position or setting the UNIT/PARALLEL switch to UNIT position, eliminates that effect of T2 during single generator operation.

B. Sensing Circuit During Parallel Generator Operation In Reactive Voltage Droop Compensation Mode Generators interconnected for reactive voltage droop compensation will proportionally share inductive reactive loads during parallel operation by a decrease in generator system voltage. This method of kVAR load sharing is described in the paragraphs that follow.

The sensing transformer(s) provides a voltage proportional to the sensing voltage. A current transformer (CT) installed in line 2 of generator develops a signal that is proportional in amplitude and phase to the line current. This signal develops a voltage across the slide-wire parallel voltage droop adjust potentiometer R4.

The tap on R4 supplies part of this voltage to the primary of transformer T2.

The voltage developed in the secondary of the sensing transformer(s) and the voltage developed in the secondary of T2 add vectorially. This action provides a voltage to the sensing diodes that is the vector sum of the stepped down sensing voltage and the parallel current transformer signal through T2. The sensing rectifier de output is filtered and applied to the error detector and underfrequency limit.

When a resistive (unity power factor) load is connected to the generator, the voltage that appears across the droop potentiometer leads the sensing voltage by 90 degrees, and the vector sum of the two voltages is nearly the same as the original sensing voltage; consequently, almost no change occurs in generator output voltage.

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When lagging power factor (inductive) load is connected to the generator, the voltage across the droop potentiometer becomes more in phase with the sensing voltage, and the combined vectors of the two voltages result in a larger voltage being applied to the sensing rectifiers. Since the action of the regulator is J to maintain a constant voltage at the sensing rectifiers, the regulator reacts by decreasing the generator output voltage.

When a leading power factor (capacitive) load is connected to the generator, the voltage across the droop potentiometer becomes out of phase with the sensing voltage and the combined vectors of the two voltages result in a smaller voltage being applied to the sensing rectifiers. Then the regulator reacts by increasing the generator voltage.

During parallel operation of two or more generators interconnected for reactive voltage droop, if field excitation on one of the generators should become excessive and cause a circulating current to flow between the generators, the circulating current will appear as an inductive load to the generator with excessive excitation and a capacitive load to the other generator( s). The para I lel components R4 and T2 wi II cause the voltage regulator of the generator with excessive field excitation to decrease the generator voltage while the voltage regulators of the other generator(s) will increase the gener:ator voltage.

C. Sensing Circuit During Parallel Generator Operation In Parallel Cross-Current Compensation Mode Parallel cross-current compensation allows two or more paralleled generators to share inductive reactive loads with no droop or decrease in the generator system output voltage when the line currents are proportional and in phase. This is accomplished by the action and circuitry described previously for parallel reactive voltage droop compensation and the interconnection of the current transformer secondaries in a closed series loop. Circulating currents cause the system to react as described previously for parallel voltage droop compensation.

A unit/parallel switch connected in each generator system eliminates the series resistance of the CT's in shut down generator sets from the CT's of the generator sets that are operating.

D. Error Detector The error detector circuitry consists of a voltage adjust circuit, a voltage divider, a two-stage differential amplifier, and an internal minor feedback filter. The voltage adjust circuit consists of an external voltage adjust rheostat VAR, a voltage range adjustment R2, and fixed resistor R1. Full travel of the external voltage adjust provides 2:..10% adjustment of the generator output voltage from nominal. The voltage range adjustment R2 establishes the maximum and/or minimum voltage adjust limit of VAR. The voltage adjust circuit and a voltage divider consisting of resistors R5 and R71 determine the input signal to the first differential amplifier.

The first differential stage is comprised of transistors 01 and 02, resistors R9 through R23, capacitor C3, Zener diode Z1, and circuitry within the underfrequency limit. Underfrequency limit (UFL) provides a reference voltage to the base of transistor 02 as described in the UFL circuit description. During generator operation at rated frequency the reference signal is constant and identical to the Zener voltage. Voltage from the sensing circuit which is proportional to the generator voltage is applied to the base of transistor

01. When 01 base voltage is different from the reference voltage applied to the base of 02, there will be a difference in 01 collector current with respect to 02 collector current.

The current from the collector of transistor 01 is divided by resistors R9 and R16 and injected into the base of the second stage differential amplifier transistor 03. Similarly, the current from the collector of transistor 02 is divided by resistors R14 and R15 and injected into the second stage differential amplifier transistor

04. Resistors R10 and C3 help to prevent oscillations at high frequencies. The second stage differential amplifier amplifies the output of the first stage differential amplifier. Components included in the second stage differential amplifier are transistors 03 and 04, and resistors R24 through R27. The collector voltage of transistor 03 controls the phase control circuit. The minor feedback filter consists of resistor RB and capacitor C2. The filter removes any remaining ac from the de signal.

E. Phase Control Circuit The phase control circuit consists of diodes D5 and D6, resistors R28 through R32, capacitors C6 and C7, Zener diode Z2 and programmable unijunction transistor (PUT) 05.

The phase control circuit is a"ramp and pedestal" control that regulates the phase angle of the power controller circuit SCR's by controlling the "turn on" signal it supplies to the gate of the SCR's. An exponential ramp voltage that starts from a voltage pedestal provides the "turn on" gating signal. Because the ramp voltage starts from the voltage pedestal, a small change in the amplitude of the pedestal voltage results in a large change in SCR phase angle.

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J

The amplitude of the pedestal voltage is determined by the collector current of second stage differential amplifier transistor 03. Zener diode Z2 serves as a voltage clamp and resistors R31 and R32 are a voltage divider which determines the threshold of the programmable unijunction transistor 05. The output of PUT 05 is applied to the gate of the power controller SCR's through resistors R43 and R44.

F. Power Stage (Power Controller)

The power stage supplies the generator exciter field current. The power stage consists of an SCA/diode bridge rectifier. The power stage input is either single phase 120 V ac or single phase 240 V ac depending on regulator design. The output of the power stage is regulated by the "turn on" gating signal its SCR's receive from the phase control circuit. The circuit includes a free wheeling diode for field discharge of the inductive exciter field load and a fuse (F1) in its input power line.

G. Field Flashing Circuit The flashing circuit includes the power stage SC R's, field effect transistor ( FET) 06, transistors 07 through 010, resistors R34 through R46, diodes 07 through 011 and capacitor CB. Transistors 08 and 09, and resistors R34, R36, R37, R38, R40 and R41 comprise a Schmidt trigger circuit. The Schmidt trigger turns on when an increasing voltage is present with magnitude approximately 70% of the nominal 24 V de output of the sensing rectifiers, and turns off when a decreasing voltage is present with magnitude of approximately 30% of the nominal output of the sensing rectifier.

When the Schmidt trigger is off, FET 06 is on. This action turns on transistors 010 and 07 which supply current to fire slave SCR1 located on the circuit board. Slave SCR1 fires the silicon controlled rectifiers SCR1 and SCR2 in the regulator power controller circuit which, when on, supply current to the exciter field.

When the Schmidt trigger turns on, FET 06 turns off. This action turns off transistors 010 and 07 which removes the gating signal to slave SCR1 and in turn the gating signal of the flashing circuit from the power controller SCR's.

H. Stability Control

The stability circuit is a rate feedback RC network. It consists of capacitors C4 and C5, resistors R7, R19 and R20, and stability adjust potentiometer R6. This RC network injects a stabilizing signal from the regulator output which helps to prevent generator voltage oscillation.

I. Underfrequency Limit (UFL)

NOTE: The underfrequency limit circuitry is not included when regulator includes the flat regulation option.

Where regulator is supplied with the V/Hz sensing option, operation and construction of the V/Hz circuitry is similar to the underfrequency limit.

The UFL provides a reference voltage to the error detector which is constant when the generator output frequency is higher than a predetermined limiting frequency. When the generator is operating slower than the predetermined UFL operational threshold, the UFL will provide the error detector with a reference voltage that is proportionally lower.

The reference voltage to the UFL is supplied by Zener diode Z1. The UFL operational threshold for standard 50 Hz, 60 Hz, and 400 Hz KCR 760 regulators are given in Section 1 in this manual. The operation of the various components comprising the UFL assembly is described in the paragraphs that follow.

The voltage from the sensing transformer is rectified by diodes 019 and 021 and the rectified signal is applied to a Schmidt trigger consisting of operational amplifier IC2A, and resistors R47 through R51. A 24 V de peak-to-peak square wave is generated at the output of IC2A at double the frequency of the sensing voltage.

The 24 V de square wave from the Schmidt trigger is fed to the first stage of a two-stage monostable multivibrator where it is decreased to a 5 V de peak-to-peak square wave at double the frequency of the sensing voltage. The 5 V de square wave is applied to the second stage of the monostable multivibrator. The monostable multivibrator output pulse is uniform in amplitude and duration for each input pulse. Thus, the average voltage level of the collective pulses at the output of the monostable multivibrator is directly proportional to the frequency of the pulses. The monostable multivibrator output is fed into a four-pole Butterworth low pass filter comprised of operational amplifier IC2B and IC2C, resistors R60 through R66, and capacitors C13 and C18. This filtering circuit does the actual averaging of the collective pulses from the monostable multivibrator. Amplifier gain is set at level where its output equals the Zener reference at rated 60 Hz or 400 Hz operation by resistors R65, R66 and capacitor C16. Where operated at rated frequency of 50 Hz, the circuit is set for 50 Hz operation by removing jumper J1. This action adds R57 to the circuit.

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Diode 012 and integrated circuit IC2D form a voltage clamping circuit. If the voltage from the Butterworth filter is equal to that of the Zener reference, the UFL output to the error detector will be the same as the Zener reference and the UFL will have no effect on regulator operation. However, when the voltage from the filter decreases as occurs during underspeed operation of the generator, the reference voltage applied to the error detector is less than the Zener reference. This action will cause the error detector differential signal to proportionally increase in a manner that results in a proportionally later turn-on signal to the regulator output SCR's. The regulator then decreases excitation and a lowering of generator output voltage occurs.

A resistive network consisting of resistors R54 and R56 and potentiometer R55 determines the underfrequency limit operational threshold. Zener diode Z3 and capacitors C9 and C10 protect the integrated circuits from damage should excessive voltage spikes occur.

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MOUNTING

SECTION 3

INSTALLATION

351-01002-00A

The voltage regulator can be mounted in any position without affecting its operating characteristics. The voltage regulator is convection cooled. Sufficient space should be retained about the regulator for heat dissipation, making electrical connections and controls adjustments. The voltage regulator can be mounted in any location where shock and vibration is not excessive and the ambient temperature does not exceed its ambient operational limits.

INTERCONNECTION

The regulator must be connected to the generator system as instructed in this section and as shown in the connection diagram provided with the generator set. An overall outline drawing that shows the location of regulator mounting provision and identifies parts of the voltage regulator is contained in Section 6. Also contained in Section 6 are typical interconnection diagrams and electrical schematics of the voltage regulator. Number 14 gauge or larger wire should be used for connections to the voltage regulator.

WARNING

De-energize generator set starting circuit before making repairs, connecting test Instruments or removing or making connections to or within the voltage regulator. Dangerous voltages are present at the voltage regulator terminal boards and within the voltage regulator when the generator set Is running. These Include the sensing voltage, power to the voltage regulator and the voltage regulator output. Accidental contact with llve conductors could result In serious electrlcal shock or electrocutlon.

CAUTION

Megger or high potential test equipment must not be used when testing the voltage regulator. Disconnect Interconnecting conductors between the generator and voltage regulator when testing generator or exciter with megger or high potential test equipment. The high voltage developed by megger or high potential test equipment wlll destroy the solid state components within the voltage regulator.

A. Single Phase 100-600 V ac Sensing (Terminals E1 and E3) Standard KCR 760 voltage regulator designed for sing le phase sensing has an internal sensing transformer (T1) as shown on Figure 3. This transformer is provided with taps on the primary winding for sensing voltages of 100 to 139, 200 to 228, 216 to 265, 375 to 458, 432 to 528 and 540 to 600 V ac. The transformer primary winding taps are identified with the corresponding nominal voltages which are 120, 208, 240, 416, 480, and 600 V ac. To obtain proper operation the internal wire from voltage regulator terminal E3 must be connected onto the correct primary tap on transformer T1. Electrical wires within the regulator connect to the sensing transformer secondary winding as shown on Figure 3.

CAUTION

Regulator sensing circuit must never be opened whlie power Is applied to the regulator Input power terminals. Loss of sensing voltage wlll result In maximum regulator output.

B. Three Phase 100-600 V ac Sensing (Terminals E1, E2 and E3) Where regulator is designed for three phase sensing the regulator includes two sensing transformers (T1 and T3) as shown on Figure 4.

Except when otherwise specified in the purchase order, the regulator sensing transformers will both include multi-tap primary winding for use with the sensing voltages described in the preceding "Single Phase 100-600 V ac Sensing" procedure.

To obtain proper operation the internal wire from voltage regulator terminal E3 must be connected to correct primary winding tap on transformer T1, and the internal wire from voltage regulator terminal E2 must be connected to the corresponding primary winding tap on transformerT3. Electrical wires within the regulator connect to the sensing transformers secondary winding as shown on Figure 4.

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C. Input Power (Terminal P1 and P2)

Before making electrical connections, refer to the wiring diagram provided with the generator. Connect input power in accordance with appropriate steps that follow.

1. Where regulator is designed for 120 V ac.2:..10% input power and 65 V de maximum continuous output, connect single phase 120 V ac power to terminals P1 and P2. Refer to Section 1 for recommended use of load isolation and voltage matching transformers.

NOTE: Jumper wire J3 on regulator circuit board is installed when regulator input power is 120 V ac2" 10% and removed when input power is 240 V ac :!:..10%.

2. Where regulator is designed for 240 V ac ± 10% input power and 125 V de maximum continuous output, connect single phase 240 V ac power to terminals P1 and P2. Refer to Section 1 for recommended use of load isolation and voltage matching transformers.

3. Where regulating system is supplied with electromagnetic interference filters, connect as shown on the wiring diagram provided with the generator set.

D.Output Power (Terminals F+ and F-)

1. Be sure regulator output matches the generator exciter rating. KCR 760 voltage regulator designed for

120 V ac input is designed for 65 V de maximum continuous output. KCR 760 voltage regulator designed for 240 V ac input is designed for 125 V de maximum continuous output.

2. Correct polarity must be maintained between the regulator output and exciter field.

3. Field resistance for 65 V de regulator…