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INSTRUCTION MANUAL
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Publication Number: 9 0750 00 990Date: January, 1979

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The SR32A Voltage Regulator is designed to regulate the output voltage of 50/60 Hertz generatorswith 32 Vdc fields. Regulation is achieved by controlling the current that the SR32A supplies to thegenerator or exciter field. The SR32A can be used on any generating system with a field excitationrequirement within its rating.

1-2. SPECIFICATIONS

Refer to Table 1-1 for the electrical specifications and to Table 1-2 for the physical specifications.

Table 1-1. Electrical Specifications.

Input Voltage 60 volts; if correct input voltage is not available, a suitablepower transformer must be used.

Frequency: 50 Hz, 60 Hz.

Volt Amps: 1200; when regulator is operated at less than maximum output,power isolation transformer rating can be determined bymultiplying input volts by DC output current.

Maximum ContinuousOutput:

32 volts, 20 amps.

Maximum 1-Minute Forcing: 45 volts, 28 amps.

Sensing Voltage: NEMA Standard 120, 208, 240, 416, 480, 600; single phase orthree phase.

Maximum Burden PerPhase:

10 VA.

Parallel Compensation: 5A input, 25 VA burden, droop adjustable to approximately 5%.

Field Resistance: 1.6 ohms minimum.

Regulation Accuracy: Within +0.5% over full range of alternator loading.

Regulator Response: Less than 17 milliseconds.

Regulator Drift: Less than +0.5% per 104°F (40°C) ambient temperaturechange.

Regulator Sensing: Single-phase or three-phase.

Power Dissipation: Less than 170 watts at continuous rating.

Voltage Adjust Range: Minimum +10% of nominal voltage.

SECTION 1

GENERAL INFORMATION

1-1. INTRODUCTION

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Table 1-2. Physical Specifications.

Overall Dimensions: 13 inches (330 mm) X 8.53 inches (217 mm) X 7.19 inches(183 mm).

Weight: Net 18 lbs. (8.16 kg); shipping 20 lbs. (9.07 kg).

Finish: Dark brown, lusterless, textured, baked enamel.

Ambient OperatingTemperature Range:

-55°C to +70°C (-67°F to + 158°F) without derating.

Storage TemperatureRange:

-65°C to +100°C (-85°F to +212°F) without degradation ofcomponents.

Vibration: Withstands up to 5 G’s at 260 Hz.

Shock: Withstands up to 15 G’s.

The model number of the voltage regulator indicates which features are included in each particularmodel. An example model number, with a key showing the manner in which features are identified,is shown in Figure 1-1. Table 1-3 lists all available features along with the model number designatorfor each.

a. Parallel compensation is controlled by either an internal adjustable resistor or an externalrheostat.

b. Single or three-phase sensing with NEMA standard voltages.

c. Internal or external voltage-adjust rheostat.

d. Stabilizing networks for use with brush or brushless rotary exciters or as a static exciter.

1-3. OPTIONAL FEATURES

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Figure 1-1. Sample Model Number

Table 1-3. Model Number Style Chart.

Sample Model Number

SR32 A 3 B 15 B 4 E

SR32 A-Surfacemounted.

1-NoParallelProvisions.

2-Parallelprovisionswithadjustableslide wireresistor.

3-Parallelprovisionswithexternalparallelrheostat.

A-No relay

B-Build-upRelay

C-Hermeticallysealed relay.

15-Selectable1-phasesensing.

16-Selectable3-phasesensing w/Fastonconnectors.

B-Cover

2-Voltageadjustrheostatinternallyinstalled.

3-Voltageadjustrheostat,suppliedseparatelywithregulator.

4-Voltageadjustrheostatinternallyinstalledw/ lockingshaft.

B-For useas staticexciter.

E-For usewithbrushlessexciter(primarilyongeneratorsrated 150kW orless) orwith allrotaryexciters.

M O D E L

VOLTAGE BUILD-UP PROVISIONS

PARALLEL PROVISIONS

SINGLE- OR THREE-PHASE SENSING

E N C L O S U R E

TYPE OF VOLTAGE ADJUSTMENT

TYPE OF STABILITY CIRCUIT

SR32 A 2 B 15 B 3

M O U N T I N G

B

D2589-0102-24-97

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Accessories are not designated in the SR model number and must be selected as separateitems. Available accessories include the following:

1. Power transformers

2 Paralleling current transformers

3 Exictation Support Systems (Series Boost Options).

4 Underfrequency - Overvoltage Control Modules

5 Manual Voltage Control Module

6 SR Regulator with RFI Suppression

7 Motor Operated Potentiometer

8 Wide Range Voltage Adjust

9 Volts-Per-Cycle Modules

10 DC Generator Voltage Control

11. VAR/Power Factor Controller

Information on these accessories may be obtained from the applicable instruction manual orproduct bulletin. Information is also available from you nearest Basler Electric SalesRepresentative or from the Factory System Sales Department.

1-4. ACCESSORIES

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2-1

Refer to Figure 2-1. The voltage regulator senses the generator voltage, compares a rectifiessample of that voltage with a reference diode (zener) voltage, and supplies the field currentrequired to maintain a predetermined ratio between the generator voltage and the referencevoltage. This unit consists of five basic circuits: a sensing circuit, and error detector, an erroramplifier, a power controller, and a stabilization network. With the exception of the powercontroller and part of the sensing circuit, all of these circuits are contained on printed circuit boardassemblies.

Figure 2-1. Input Phase Relationship.

Relay K-1 provides automatic voltage buildup form generator residual voltage. A normally closedcontact (relay de-energized) provides a current path to fire the control rectifiers to allow thegenerator residual voltage to be converted to dc by the diodes (CR13, CR14) and rectifiers(CR11, CR12). This dc voltage is then applied to the exciter field. When the generator voltagereaches approximately 75% of rated, the relay pulls in, removing the buildup circuit and allowingthe control rectifiers to regulate the generator output voltage. A minimum 3V generator residualis required for automatic voltage buildup. If residual is less than 3V, external field flashing maybe required.

SECTION 2

THEORY OF OPERATION

2-1. FUNCTIONAL CIRCUIT

2-2. AUTOMATIC VOLTAGE BUILDUP

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In brushless exciter (or static exciter) applications, the exciter output is not available for self-excitation during heavy loading. The addition of a Series Booster Option (SBO), Patent No.3,316,479, prevents collapse of excitation by providing constant voltage to the regulator for alloperating conditions.

A. When parallel operation is required, the following additional components are required in theregulating system:

1. Resistor R252. Transformer T33. Current Transformer CT1

Two of the components, R25 and T3, are included in a parallel-equipped voltage regulator. Current Transformer CT1 is a separate item and must be interconnected as shown in Figure 3-2.

B. These components allow the paralleled generators to share reactive load and reducecirculating reactive currents between them in the following manner:

(1) The current transformer (CT1) is installed in line 2 of each generator. It develops asignal that is proportional in amplitude and phase to the line current. This current signaldevelops a voltage across resistor R25. A slider on R25 supplies a part of this voltage tothe primary of transformer T3. The secondaries of T3 are connected in series with theleads from the secondary of the sensing transformer T1 and the sensing rectifiers locatedon the printed circuit board. The ac voltage applied to the sensing rectifier bridge is thevector sum of the stepped-down sensing voltage (terminals E1 and E3) and the parallelCT signal supplied through T3 (terminals 1 and 2). The voltage supplied to the sensingrectifiers by the parallel CT is very small in relation to the signal supplied by the sensingvoltage. The regulator input sensing voltage (terminals E1 and E3) and the parallelcompensation signal (terminals 1 and 2) must be connected to the generator system soas to provide the correct phase and polarity relationship.

(2) When a resistive (unity power factor) load is applied to the generator, the voltage thatappears across R25 (and T3 windings) leads the sensing voltage by 90 degrees. Thevector sum of the two voltages is nearly the same as the original sensing voltage. Consequently, almost no change occurs in generator output voltage.

(3) When a lagging power (inductive) load is applied to the generator, the voltage acrossR25 becomes more in phase with the sensing voltage. The combined vectors of the twovoltages results in a large voltage being applied to the sensing rectifiers. Since theaction of the regulator is to maintain a constant voltage at the sensing rectifiers, theregulator reacts by decreasing the generator output voltage.

(4) When a leading power factor (capacitive) load is applied to the generator, the voltageacross R25 becomes out of phase with the sensing voltage. The combined vectors ofthe voltage results in a smaller voltage being applied to the sensing rectifiers. Theregulator reacts by increasing the generator voltage.

(5) If two generators are operating in parallel and the field excitation on one generatorbecomes excessive, a circulating current can flow between the generators. This currentwill appear as a lagging power factor (inductive) load to the generator with excessive field

2-3. MOTOR STARTING OR SHORT CIRCUIT OPERATION

2-4. PARALLEL OPERATION

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current and as a leading power factor (capacitive) load to the other. On the generatorwith the lagging power factor load, the parallel compensation circuit will cause the voltageregulator to decrease the field excitation. On the generator with the leading power factorload, the parallel compensation circuit will cause the voltage regulator to increase thefield excitation. This will minimize the circulating current between the generators. Thisaction and circuitry is called parallel droop compensation. It allows two or moreparalleled generators to proportionally share inductive loads by causing a decrease ordroop in the generator system voltage.

C. Parallel cross-current compensation (reactive differential compensation) allows two or moreparalleled generators to share inductive reactive loads with no decrease or droop in the generatorsystem output voltage. This is accomplished by the circuitry described above for parallel droopcompensation with the addition of cross-connecting leads between the parallel CT secondariesas shown in Figure 3-3, “Interconnection Diagram.” By connecting the finish of one parallel CT tothe start of another, a closed series loop is formed that interconnects the CT’s of all generators tobe paralleled. The signals from the interconnected CT’s cancel each other when the line currentsare proportional, in phase, and no system voltage decrease occurs. These regulators provide thecircuit isolation necessary for parallel cross-current compensation.

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3-1

The voltage regulator can be mounted in any position without affecting its operatingcharacteristics; however, the unit should be vertically mounted to obtain optimum cooling. Theregulator can be mounted in any location where the ambient temperature remains within -55°C to+ 70°C (-67°F to +158°F). Due to its rugged construction, the regulator can be mounted directly on the generator. The overall mounting dimensions are shown in Figure 3-1, “Outline Drawing.”

Figure 3-1. Outline Drawing.

SECTION 3

INSTALLATION AND INTERCONNECTION

3-1. MOUNTING

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A. Wire Gauge

The regulator must be connected to the generator system as instructed in this section and asshown in Figure 3-3, “Interconnection Diagram.” Number 16 gauge wire (or larger) should beused for all connections to the regulator.

B. Regulator Sensing (Terminals E1, E2, and E3)

(1) The regulator has one or two internal sensing transformers (T1 or T1+T2). These areprovided with taps for input sensing voltages of 120, 208, 240, 416, 480, and 600 Vac (refer toFigure 3-2). The model number of the unit designates single phase (T1) or three-phase(T1+T2) sensing. See the “Optional Features” section for model number interpretation. Foroperation with generator voltages above 600 volts, a potential transformer (or transformers)must be used to supply the regulator sensing voltage. This transformer should be of meteringquality. The regulator sensing circuit load is less then 10 VA; correct polarity must bemaintained to the regulator sensing input.

(2) On single-phase sensing models, the voltage sensing leads are connected to terminals E1and E3. For three-phase sensing, terminals E1, E2, and E3 are used. For precise voltageregulation, the sensing leads should be connected as close as possible to the point whereregulation is desired.

(3) SR32A Voltage Regulators are factory preset for 120 Vac sensing voltage. If the sensingvoltage needs to be changed for your installation, perform the following steps.

Step 1. Remove the cover if applicable.

Step 2. Remove 9 hex screws.

Step 3. Remove the printed circuit board without disconnecting the wires.

Step 4. Locate transformer(s) T1 for single-phase sensing units (T1 and T2 for three-phase sensing units). These transformers are equipped with Fastonconnectors for changing sensing taps.

Step 5. For single-phase sensing units, move the wire that is factory connected to T1-120 terminal to the T1 terminal labeled with the desired sensing voltage.

Step 6. For three-phase sensing units, move the wire that is factory connected to T1-120 terminal to the T1 terminal labeled with the desired sensing voltage. Also, move the wire from T2-120 terminal to the T2 terminal labeled with thedesired sensing voltage.

3-2. INTERCONNECTION

CAUTION

Meggers and high potential test equipment should be used withextreme care. Incorrect use of such equipment could damagecomponents contained in the device.

WARNING

All SR32 Voltage Regulators are shipped factory preset for 120Vac sensing.

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Figure 3-2. Top View of Voltage Regulator.

(4) The regulator regulates the voltage that is applied to its sensing terminals. Therefore, itcannot correct for voltage drop in leads that may occur at points other than where theregulator sensing leads are connected. The leads that supply regulator sensing should not beused to supply power to any other equipment or to the regulator power stage (terminals 3 and4).

(5) If the generator is to be operated in parallel with other generators, the phase relationshipof sensing voltage and the parallel current transformer is very important. See “ParallelCompensation “ below for further information.

C. Field Power (Terminals F+ and F-)

(1) The model number prefix SR32 defines the amount of power (32 volts, 20 amps,continuous) the unit is designed to deliver. See the “Optional Features” section for modelnumber interpretation.

(2) The dc resistance of the field to which the regulator is connected (terminals F+ and F-)must be equal to or greater than 1.57 ohms for the SR32. If the resistance is less than thespecified minimum, a resistor must be added in series with the field. This resistor value plusthe field resistance must exceed the minimum preceding value.

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(3) Good generator voltage stability usually results when the regulator output is above 10 Vdcat no load. If the voltage is less and a voltage stability problem exists, it may be necessary toadd resistance in series with the field. The resistance raises the regulator output voltage,thereby increasing the stability signal.

Figure 3-3. Interconnection Diagram

(4) When adding resistance in series with the field, the resistor value must not restrict fieldforcing during full load conditions. The following example explains how to compute the properresistance:

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D. Input Power (Terminals 3 and 4)

(1) For input power maximums, see the “Optional Features” section. The current requirement ofthe field with which the regulator is operating will determine the actual input current. The nominalvoltage applied to the regulator input power stage (terminals 3 and 4) must be 60V for the SR32. The input power may be taken from any generator line that provides the correct voltage (line toline or line to neutral). The phase relationship of this input to the other circuits is not important.

(2) When the generator output voltage is other than 60V, a power transformer must be used tomatch the generator voltage to the regulator input. If excessive voltage is applied to the regulatorinput (terminals 3 and 4), the diodes and SCR’s in the power controller circuit may be destroyed.

(3) If the field or field flashing circuit is grounded, a power transformer must be used to isolatethe regulator input from ground. Without the use of this transformer, a ground at any point in thefield circuit and another ground in the generator output will destroy the SCR bridge.

(4) On single phase sensing models, it is recommended that the input power be taken from aphase other than the one used for input sensing.

E. Parallel Compensation (Terminals 1 and 2)

(1) In addition to the regulator provisions, a 25 VA current transformer (CT) is also required (seeFigure 3-3, “Interconnection Diagram”). The CT is connected in a generator line and shoulddeliver form 3 to 5 amperes secondary current at rated load.

(2) The CT signal/regulator sensing voltage phase relationship must be correct or the systemswill not parallel properly. On three-phase sensing models, the CT must be installed in the linethat supplies sensing voltage to regulator terminal E2. On single-phase models, the CT must beinstalled in the line that does not supply sensing to the regulator.

(3) Figure 3-4, “Reactive Differential Compensation (Cross-Current Compensation) CT’sInterconnection,” shows the correct CT polarity for L1-L2-L3 phase rotation. If the phasesequence is L1-L3-L2, the CT secondary leads must be interchanged. The correct CT secondarypolarity can be determined by the test found in paragraph 4.8.C. “Preliminary Operation.”

(4) For droop compensation, connect the CT to its respective regulator as shown in Figure 3-4.

(5) For cross-current compensation, connect each CT to its respective regulator and connectthe CT’s in series; connect the finish of the first CT to the start of the second CT, the finish of thesecond CT to the start of the third CT, etc. until all CT’s are connected. The final step will be toconnect the finish of the last CT to the start of the first CT (see Figure 3-4).

EXAMPLEAn SR32 voltage regulator is required to operate with an exciter field that has adc resistance of 1 ohm and current requirements of 7.0 Adc at no load and 15Adc at full load. Since the SR32 requires a minimum field resistance of 1.57ohms, a resistor of at least 0.57 ohms must be connected in series with the field. The regulator output will be 1.57 ohms times 7.0 A, or 11.0 Vdc, and 1.57 ohmstimes 15 A, or 23.5 Vdc, at full load. This conforms to the 10 volts minimum at noload and provides a sufficient amount of forcing at full load (up to 45 Vdc).

CAUTION

Excessive input voltage can destroy the diodes and SCR’s in thepower controller circuit. Also, failure to isolate the regulator inputfrom ground can result in destruction of the SCR bridge.

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(6) A Unit-Parallel switch shorts the parallel CT secondary to prevent any droop signal frombeing applied to the regulating system during single unit operation. The switch may not berequired on parallel droop compensation applications in which a voltage drop is unobjectionable.

(7) On parallel cross-current compensation applications consisting of more than two generators,a Unit-Parallel switch should be used if all the generators are not always on the load bus. If theswitch is not used, a voltage droop will be introduced into the system. This is because theunloaded generator voltage CT does not supply a compensating signal, but instead allows avoltage drop across the CT. This drop also causes the voltage of the incoming generator tofluctuate prior to paralleling. Ideally, this switch is an auxiliary contact on the circuit breaker thatopens when the circuit breaker is closed.

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Figure 3-4. Reactive Differential Compensation(Cross-Current Compensation) CT’s Interconnection

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The following procedures should be reviewed before initial operation is attempted. Startupprocedures are detailed in the “Initial Operation” and “Field Flashing” sections.

Do not operate the generating system at reduced speeds with the voltage regulator in operationunless adequate precautions are taken to protect the regulator. If operation at reduced speed isessential, either remove input power from the regulator or add an Underfrequency/OvervoltageModule to the system. For information on this module, see the “Optional Features” section.

Your regulator may be equipped with an input power switch to allow the removal of excitationfrom the field in an emergency or when the generator prime mover must be operated at reducedspeed . This switch is shown in Figure 3-3, “Interconnection Diagram.” If this switch is not used,it is recommended that the input power switch be temporarily installed for initial operation.

When used, the input power switch must always be installed in the input power line to theregulator (terminals 3 or 4). Do not install a switch in the field circuit (terminals F+ of F-). Also ashutdown circuit using field discharge resistors is not required and should not be used.

SECTION 4

OPERATING INSTRUCTIONS

4-1. INTRODUCTION

WARNING

All SR32A Voltage Regulators are shipped factory preset for120 Vac sensing.

4-2. OPERATION AT REDUCED SPEEDS

CAUTION

Without adequate protection, prolonged operation at speeds lowerthan normal can cause the complete destruction of the voltageregulator and the exciter field.

4-3. VOLTAGE SHUTDOWN

CAUTION

If the input power switch is installed in the field circuit (terminals F+of F-), a high flyback voltage will develop. To avoid high voltagearcing, the field circuit must never be opened during operation.

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The adjustments pertaining to the regulator and system operation are described in the followingparagraphs. These adjustments are made during initial operation and normally do not have to berepeated during the life of the regulator.

A. Stability Adjustment (R4)

This adjustment provides stable regulator operation. It controls the amount of feedback that isapplied to the error amplifier stage. Normally, the stability adjustment is factory set in theextreme clockwise (CW) position. This setting normally assures good stability, but tends to slowthe generator response time. If rotated counterclockwise (CCW), system response timequickens. However, if rotated too far CCW, the generator voltage may oscillate (hunt). If thegenerator voltage hunts, the adjustment should be rotated CW well ahead of the point whereoscillation occurs. The system voltage stability is critical at no load. If a setting is desired thatprovides the fastest possible voltage response with good generator stability, an oscilloscope orsome voltage recording device should be used.

B. Generator Voltage Adjust Rheostat (R1)

This adjustment controls the generator voltage. When adjusted to its maximum resistanceposition (CCW), minimum generator voltage is obtained. Maximum generator voltage is obtainedwith minimum resistance (CW).

C. Nominal Voltage Range Set Adjust (R3)

This adjustment varies the limits of R1. Normally R3 is set to provide R1 with and adjustmentrange of +10% of rated voltage.

Before initial operation is attempted, verify that the regulator is connected correctly as shown inFigure 3-3, “Interconnection Diagram.

The initial operating instructions should be completely reviewed and understood before systemoperation is attempted. Controls and adjustments pertinent to system operations also should bereviewed.

A. Single Unit Operation (No Load)

(1) Start the prime mover and bring up to rated speed. If a voltage shutdown switch is used(see the “Voltage Shutdown” section), close the switch to apply excitation. If this switch is notused, generator voltage will build up automatically. If field flashing is necessary, see the“Field Flashing” section below.

(2) Verify generator voltage; check for the following conditions:

a. If overvoltage (+15% or more) exists, immediately open the shutdown switch or stopthe prime mover. Determine the cause of the overvoltage. If necessary, refer to the“Troubleshooting” section.

4-4. ADJUSTMENTS

4-5. WIRING VERIFICATION

4-6. INITIAL OPERATION

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b. If voltage fails to build up, field flashing may be required. Refer to the “FieldFlashing” section.

c. If undervoltage (-15% or more) exists, stop the prime mover and determine thecause of the undervoltage. If necessary, refer to the “Troubleshooting” section.

d. If voltage build up and collapses, stop the prime mover and determine the cause ofthe collapse. If necessary, refer to the “Troubleshooting” section.

e. If voltage oscillates (hunts), refer to the “Troubleshooting” section. Voltage huntingcan be caused by an unstable prime mover.

(3) If voltage is unstable, perform the following step:

a. Loosen the locking nut on R4.

b. Rotate R4 clockwise (CW) approximately 30° beyond the point where stableoperation is obtained. If this step does not stabilize the voltage, refer to the“Interconnection” section, paragraph 3.2.C, “Field Power.”

c. Tighten lock nut on R4.

(4) To adjust the voltage range +10%, perform the following steps:

a. Verify R1 is adjusted to the center of its travel.

b. Loosen the locking nut on R3 and adjust to obtain the rated generator voltage.

c. Tighten the lock nut on R3.

(5) Load test the voltage regulator as follows:

a. Apply load to the generator.

b. Verify the voltage regulation is within +0.5%. If regulation is not within this range, refer to the “Troubleshooting” section.

c. Alternately remove and apply the load to determine if the generator voltage is stable.

d. If the generator voltage becomes unstable, adjust R4 for stable operation. If adjusting R4 does not stabilize the voltage, see paragraph 4.6.B below, “Increasing

Stability.”

B. Increasing Stability

(1) Instability may occur when the no-load field requirements of the exciter or generator arenear the minimum working voltage of the regulator. Increased stability may be obtained byadding a resistor in series with the field. See the “Interconnection” section, paragraph 3.2.C,“Field Power.”

(2) An unstable governor is frequently the cause of generator voltage instability. If a stabilityproblem persists after performing the steps in 4.6.A, and 4.6.B, thoroughly check thegovernor.

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The following procedure is for use on systems that do not build up generator voltage and have nofield flash provision incorporated. Usually, there is sufficient residual magnetism to allow thegenerator voltage to build up without an additional flashing circuit. See the “Automatic VoltageBuildup” section.

A. With the prime mover at rest (not rotating), apply a dc flashing source across terminal F+ andF- on the regulator. The positive of the flashing source must be connected to F+ and thenegative must be connected to F-.

B. If automatic field flashing is required, a dc source not in excess of 125V should be used. Thecircuit must be interconnected as shown in Figure 3-3, “Interconnection Diagram.” The flashingsource must not provide more than 50% of the current required for no-load output. The blockingdiode in series with the regulator F- terminal prevents the regulator output from flowing into theflashing source.

The following paragraphs describe the procedure for operating two or more generator sets inparallel.

A. Prerequisites

To ensure proper parallel operation, the following requirements must be met:

(1) The voltage regulating systems must cause the generators to share the total KVAR load.

(2) The speed governing system must cause the generators to share the total KW load.

B. Preliminary Instructions

(1) A review of the operation of components that facilitate operation is recommended. These include components external to the regulator as well as components within theregulator. See section 2.4, “Parallel Operation.”

(2) It is essential that the paralleling signal at terminal 1 and 2 of the regulator have theproper phase relationship with the sensing voltages at terminals E1, E2 (if used), and E3. Verify the connections to these terminals are exactly as shown in Figure 3-3,“Interconnection Diagram.”

(3) If cross-current compensation is desired, the paralleling CT’s must be connected asdescribed in paragraph 3.2.E, “Parallel Compensation.” A CT must be selected that willfurnish 3 to 5 amperes at rated generator load current.

(4) Prior to operation, the slide adjustment of resistor R25 on each regulator should beset to the same position: near the end of R25 (farthest from the terminal strip). Thisadjustment provides maximum droop signal .

4.7 FIELD FLASHING

CAUTION

The flashing source cannot be grounded unless a power isolationtransformer is used.

4-8. PARALLEL OPERATION

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C. Preliminary Operation

(1) Before attempting to parallel two or more generator sets, it is recommended that theindividual sets be tested as follows to verify that the paralleling features function properly:

a. Place each set in operation in accordance with paragraph 4.6.A, “Single UnitOperation, No Load.”

b. Verify the paralleling CT secondary is not shorted; unit/parallel switch inPARALLEL position.

c. Apply 25% to 100% unity power factor load to set under test. Generator voltageshould change less than 1%. If governor is set for droop operation, frequencyshould decrease.

d. Apply 25% to 100% 0.8 power factor (inductive) load. Voltage should droop from4% to 6% with rated load. If voltage rises instead of drooping, reverse the CTsensing leads.

(2) During the tests, verify voltage and speed do not drift or jump erratically. Also, generatorvoltage sequence can be verified during the tests.

D. Conditions Necessary for Paralleling

To prevent damage to the generator or the prime mover or both, paralleling should be attemptedonly when the speeds (frequencies) are equal, at the instant when the generator voltages arealso equal. That is, the generators have the same phase sequence of voltage and the voltagesare in phase.

E. Metering

To initiate paralleling and to check for proper parallel operation, all generators should beequipped with the following monitoring equipment:

(1) AC Voltmeter (1 or 2)(2) Frequency Meter (1 or 2)(3) Synchroscope or set of lights; used to indicate an in-phase condition(4) Ammeter, ac (1 per set)(5) KW meter (1 per set)(6) KVAR or Power Factor Meter (1 per set)(7) Field ammeters

F. Sequence of Operation (Parallel)

(1) The following instructions contain the proper procedure for paralleling generators. This procedure should be completely reviewed, understood and walked through before paralleling is attempted.

a. Start generator set No. 1.

b. Close circuit breaker connecting No. 1 to bus.

c. Adjust voltage and frequency to nominal.

d. Apply load. If possible, load should be 10% or more of unit KW rating.

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e. Start generator set No. 2.

f. Adjust No. 2 voltage to nominal.

g. Adjust No. 2 speed to slightly higher than speed of No. 1.

h. Observe synchroscope or synch lights. When No. 2 is in phase with No. 1, closethe circuit breaker connecting No. 2 to the bus.

i. Immediately after closing breaker, verify indication on ammeter for set No. 2. Ammeter should read well within the rating of the generator. If reading is beyondthe generator’s rating, shut down the system and refer to the “Troubleshooting”section. If operation is unstable, see paragraph 4.8.F(3). If stable, proceed tothe next step.

j. Adjust speed of No. 2 to the point where each set is carrying the desired shareof kW load.

k. Adjust voltage of No. 2 until ammeter readings of both sets are near minimum.

l. If KVAR or power factor meters are available, adjust voltage adjust rheostat forequal or proportional KVAR or power factor readings.

m. If sets are equipped with power factor meters instead of kW meters, alternatelyadjust the speed and voltage on No. 2 until the ammeter readings areproportional and the power factor readings are equal.

n. With full load applied, readjust the speed and voltage on No. 2 until the desiredload division is obtained.

(2) The best adjustment is obtained when both sets are supplying the same percentageof rated current, kW or power factor readings are equal, or the sum of the ammetercurrents of the sets is minimum.

(3) Closing the circuit breaker for set No. 2, step 4.8.F(1)h, may result in improperoperation. The ammeter reading may be very high and the circuit breaker may opendue to current overload or reverse power play, Isolate this problem to a faulty speedor faulty voltage regulating system by performing the following steps:

a. Parallel the generators as instructed in 4.8.F(1), steps (a) through (h).

b. Immediately after closing the circuit breaker, observe the kW or power factormeters. If a high ammeter reading is accompanied by a large kW unbalance, afaulty speed regulating system is indicated. If a high ammeter reading isaccompanied by a KVAR unbalance, a faulty voltage regulating system isindicated.

(4) An alternate method of isolating the cause for the preceding problem is to parallelthe generators using manual voltage control (if available). If proper operation isobtained, a faulty voltage regulating system is indicated. If not, a faulty speedregulating system is indicated.

NOTE

To obtain best results, final adjustments should be made with fullload on the bus.

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(5) If a faulty voltage regulating system is indicated, verify the wiring and reviewparagraph 3.2.E, “Parallel Compensation (Terminals 1 and 2),” before removing theregulator. It has been found that most problems encountered with the voltageregulator in attempting to parallel generators are due to improper wiring.

(6) To parallel additional generator sets, repeat the procedure for paralleling set No. 2.

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5-1

The Voltage Regulator should be inspected on a regular basis to ensure that the unit is free frommoisture and accumulations of dust. When inspecting the unit, check that all parts are securelymounted and that all electrical connections are clean and secure. Any accumulation of dustshould be removed from the unit with a soft brush or with an air line that has a moisture trap.

Repairs to the regulator can be made by following the “Troubleshooting” section. Due to aprotective transparent conformal coating, repairs to the printed circuit board are difficult andshould not be attempted.

Table 5-1 lists parts and assemblies that have maintenance significance. When ordering anypart from Basler Electric Company, always specify the description of the item, the completemodel number, the unit serial number, the part number, and the quantity required.

Table 5-1. Replacement Part List.

Reference Description Basler Part Number

CB Circuit Board Assembly Used on SR32 __________*

CR11, CR12 Silicon Controlled Rectifier 07754

CR8, CR13, CR14,CR15, CR16 Diode 07267

T3 Transformer BE 09024 002

----------------- Sensing Transformer(s) Used on SR32 ___________*

L1 Filter Choke BE 08794 003

K1 Relay 02686

R25 Paralleling Rheostat 02662

R1 Voltage Adjust Rheostat 03456

*Use model number. See “Optional Features” section for interpretation of model number.

The more common generator system malfunctions and the appropriate repair actions are listed inTable 5-2.

SECTION 5

MAINTENANCE, REPLACEMENT PARTS, ANDTROUBLESHOOTING

5-1. PREVENTIVE MAINTENANCE

5-2. CORRECTIVE MAINTENANCE

5-3. REPLACEMENT PARTS

5-4. TROUBLESHOOTING

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Table 5-2. Troubleshooting Chart

MALFUNCTIONTEST OR INSPECTION

CORRECTIVE ACTION

1. VOLTAGE DOES NOT BUILD UP TO RATED VALUE.

Step 1. Check for low residual voltage and/or incorrect polarity relationship between exciteroutput and generator field.

If either condition exists, flash the generator field.

If neither condition exists, proceed to Step 2.

Step 2. Verify that the Voltage Shutdown Switch is closed.

If the Voltage Shutdown Switch is open, close the switch.

If the Voltage Shutdown Switch is closed, proceed to Step 3.

Step 3. Verify that the prime mover is operating at rated speed.

If the prime mover is not operating at rated speed, adjust speed.

If prime mover is operating at rated speed, proceed to step 4.

Step 4. Incorrect or missing voltage at regulator power input terminals (3 & 4).

If this condition exists, repair wiring.

If this condition does not exist, proceed to step 5.

Step 5. Verify regulator output voltage at terminals F+, F-, and A-.

If voltage is incorrect or missing, repair wiring and/or adjust/repair regulator.

If voltage is correct, proceed to step 6.

Step 6. Verify that generator output is neither shorted nor overloaded.

If generator output is shorted, remove short and repair wiring.

If generator is overloaded, shed excess load.

If generator output is not overloaded or shorted, proceed to step 7.

Step 7. Verify that the External Voltage Adjust Potentiometer (R1) is properly wired.

If the External Voltage Adjust Potentiometer is incorrectly wired, reconnect wiringproperly.

If the External Voltage Adjust Potentiometer is correctly wired, proceed to step 8.

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Table 5-2. Troubleshooting Chart - Continued.


CORRECTIVE ACTION

1. VOLTAGE DOES NOT BUILD UP TO RATED VALUE - Continued.

Step 8. Verify that the exciter wiring is correct.

If the exciter wiring in incorrect, reconnect the exciter.

If the exciter wiring is correct, proceed to step 9.

Step 9. Check for a defective exciter.

If exciter is defective, repair or replace the exciter.

If the exciter is not defective, proceed to step 10.

Step 10. Verify the regulator’s sensing transformers are on the correct taps.

Change taps for the correct nominal voltage.

Step 11. If the above steps fail to correct the malfunction, replace or repair the voltageregulator.

2. VOLTAGE BUILDS UP UNTIL RELAY ACTUATES, THEN DECAYS.

Step 1. Check for a defective Voltage Adjust Rheostat (R1) and/or defective associatedcircuitry.

If the circuitry is defective, repair the circuit/wiring.

If the rheostat is defective, replace the rheostat.

If neither the rheostat or the circuit is defective, proceed to step 2.

Step 2. Check for input power to terminals 3 and 4 (Brush-type Rotary Exciters ONLY. Allothers proceed to step 3.)

If power is not present, check and repair wiring as necessary.

If power is present, proceed to step 3.

Step 3. If the above steps do not correct the malfunction, replace or repair the voltage regulatoras necessary.

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CORRECTIVE ACTION

3. VOLTAGE HIGH AND UNCONTROLLABLE WITH VOLTAGE ADJUST RHEOSTAT -

Step 1. Check for sensing voltage at terminals E1, E2, and E3.

If sensing voltage is not present, repair wiring.

If sensing voltage is present, proceed to step 2.

Step 2. Check that the transfer switch (if used) is in AUTO position. (If transfer switch is notused, proceed to step 3.)

If transfer switch is not in AUTO position, place in AUTO.

If transfer switch is in AUTO position, proceed to step 3.

Step 3. Check for a shorted external Voltage Adjust Potentiometer (R1).

If Voltage Adjust Potentiometer is shorted, replace Voltage Adjust Potentiometer.

If Voltage Adjust Potentiometer is not shorted, proceed to step 4.

Step 4. Verify that the sensing transformer is set to the proper tap.

If transformer tap is improperly selected, reconnect to proper tap.

If transformer tap is properly selected, proceed to step 5.

Step 5. Check for a faulty relay (K1).

If relay K1 is defective, replace relay.

If relay K1 is not defective, proceed to step 6.

Step 6. If the above steps fail to correct the malfunction, replace or repair the voltage regulatoras necessary.

4. VOLTAGE HIGH AND CONTROLLABLE WITH VOLTAGE ADJUST RHEOSTAT.

Step 1. Check that the sensing transformer is set to the proper tap.



Step 2. Check that Voltage Range Adjust Potentiometer (R3) is not set too high.

If Voltage Range Adjust Potentiometer is set too high, adjust potentiometer.

If Voltage Range Adjust Potentiometer setting is within limits, proceed to step 3.

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CORRECTIVE ACTION

4. VOLTAGE HIGH AND CONTROLLABLE WITH VOLTAGE ADJUST RHEOSTAT - Continued.

Step 3. Check that the Voltage Adjust Potentiometer (R1) resistance is not too low.

If the Voltage Adjust Potentiometer resistance is too low, replace potentiometer withone of the proper value.

If the Voltage Adjust Potentiometer resistance is proper, proceed to step 4.

Step 4. Verify that the sensing leads are properly connected to the generator and regulator.

If the sensing leads are improperly connected, reconnect properly.

If the sensing leads are properly connected, proceed to step 5.

Step 5. Verify that three-phase sensing is applied to regulator. (Three-phase sensing modelsonly. For single-phase sensing models, proceed to step 6.)

If single-phase sensing is applied, reconnect for three-phase sensing.

If three phase sensing is applied, proceed to step 6.

Step 6. Verify the accuracy and connection of the voltmeter.

If voltmeter is improperly connected, reconnect voltmeter properly.

If voltmeter is defective, replace voltmeter.

If voltmeter is connected properly and not defective, proceed to step 7.


5. VOLTAGE LOW AND CONTROLLABLE WITH VOLTAGE ADJUST RHEOSTAT.

Step 1. Check that the sensing transformer is set to the proper tap.



Step 2. Check that Voltage Range Adjust Potentiometer (R3) is not set too low.

If Voltage Range Adjust Potentiometer is set too low, adjust potentiometer.

If Voltage Range Adjust Potentiometer setting is within limits, proceed to step 3.

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CORRECTIVE ACTION

5. VOLTAGE LOW AND CONTROLLABLE WITH VOLTAGE ADJUST RHEOSTAT - Continued.

Step 3. Check that prime mover is operating at rated speed.

If prime mover is operating below rated speed, adjust prime mover speed to rated.


Step 4. Verify that the sensing leads are properly connected to the generator and regulator.

If the sensing leads are improperly connected, reconnect properly.

If the sensing leads are properly connected, proceed to step 5.

Step 5. Verify the accuracy and connection of the voltmeter.

If voltmeter is improperly connected, reconnect voltmeter properly.

If voltmeter is defective, replace voltmeter.

If voltmeter is connected properly and not defective, proceed to step 6.


6. POOR REGULATION.

Step 1. Verify that exciter/generator field requirements are not in excess of voltage regulatorcapability.

If regulator application is incorrect for regulator, contact Basler Electric.

If regulator application is within regulator limits, proceed to step 2.

Step 2. Verify that input voltage at terminals 3 and 4 is of the correct value.

If input voltage is incorrect, apply correct voltage to terminals 3 and 4.

If input voltage is correct, proceed to step 3.

Step 3. Check that the voltmeter is connect to the same location as the regulator sensing.

If voltmeter is not connected to same location as the regulator sensing, reconnectvoltmeter.

If voltmeter is properly connected, proceed to step 4.

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CORRECTIVE ACTION

6. POOR REGULATION - Continued.

Step 4. Check that the generator output waveform is not distorted due to harmonic content(Regulator senses average voltage; meter may be indicating RMS values.)

If this condition exists, consult the generator manufacturer.


Step 5. Check that the UNIT/PARALLEL switch (if installed, if not go to step 6) is in thePARALLEL position when the generator is paralleled and in the UNIT position whenthe generator is operating alone. Also check that the switch functions properly.

If the switch is not in the proper position, set switch to correct position.

If the switch is defective, replace switch.

If the switch is set to the proper position, proceed to step 6.

Step 6. Check that load is not unbalanced as regulator averages all three phases together. (Three-Phase Sensing ONLY. All others proceed to step 7.)

If load is unbalanced, balance load.

If load is balanced, proceed to step 7.

Step 7. Verify that prime mover is operating at rated speed.

If prime mover is not operating at rated speed, change prime mover speed to rated.


Step 8. Check for fault in either exciter or generator.

If a fault exists, correct fault condition.

If a fault does not exist, proceed to step 9.


7. POOR VOLTAGE STABILITY.

Step 1. Verify that the generator frequency is stable.

If the frequency is unstable, consult with the governor manufacturer.

If the frequency is stable, proceed to step 2.

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CORRECTIVE ACTION

7. POOR VOLTAGE STABILITY - Continued.

Step 2. Verify that voltage does not fluctuate to the point when K1 either energizes or de-energizes.

If this condition occurs, refer to MALFUNCTION 2.


Step 3. Verify that the sensing voltage and input power are not taken from the same powerisolation transformer secondary.

If the above condition exists, reconnect sensing to a separate source.

If the above condition does not exist, proceed to step 4.

Step 4. Verify that R4 is not maladjusted.

If R4 is maladjusted, adjust R4 to proper setting.

If R4 is not maladjusted, proceed to step 5.

Step 5. Verify that the no-load field voltage is at rated.

If the no-load field voltage is below rated, refer to paragraph 3-2c,

If the no-load field voltage is at rated, proceed to step 6.

Step 6. Check for fault in either exciter or generator.

If a fault exists, correct fault condition.

If a fault does not exist, proceed to step 7.


8. VOLTAGE RECOVER SLOW WITH LOAD CHANGE.

Step 1. Verify that the correct regulator is being used for the application.

If the incorrect regulator is being used, contact Basler Electric.

If the correct regulator is being used, proceed to step 2.

Step 2. Verify that R4 is not maladjusted.

If R4 is maladjusted, adjust R4 to proper setting.

If R4 is not maladjusted, proceed to step 3.

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CORRECTIVE ACTION

8. VOLTAGE RECOVER SLOW WITH LOAD CHANGE - Continued.

Step 3. Verify that the generator frequency is stable.

If the frequency is unstable, consult with the governor manufacturer.

If the frequency is stable, proceed to step 4.


9. PARALLEL GENERATORS DO NOT DIVIDE REAL KW LOAD EQUALLY.

Consult with the governor manufacturer for improving the power sensing of the governor and/oradjustment of the governor droop setting.

10. NO REACTIVE DROOP COMPENSATION CAN BE OBTAINED FOR PARALLELGENERATORS.

Step 1. Verify that the tap on R25 is not set to the minimum position.

If the tap is set to the minimum position, adjust R25 to obtain the required droop.

If the tap is set properly, proceed to step 2.

Step 2. Verify that the Parallel CT provides the required 3 to 5 A secondary current.

If the CT does not provide the required 3 to 5 A secondary current, refer to paragraph3-3.

If the CT does provide the required 3 to 5 A secondary current, proceed to step 3.

Step 3. Verify that terminals 1 and 2 of the regulator are not shorted by the UNIT/PARALLELswitch.

If the switch is set to UNIT, set switch to PARALLEL.

If the terminals are shorted, replace the switch and/or repair the wiring.

If the terminals are shorted, proceed to step 4.


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CORRECTIVE ACTION

11. PARALLEL GENERATORS DO NOT DIVIDE REACTIVE KVAR LOAD EQUALLY.(Circulating Reactive Current Between Generators.

Step 1. Verify that the tap on R25 is not set to the minimum position.

If the tap is set to the minimum position, adjust R25 to obtain the required droop.

If the tap is set properly, proceed to step 2.

Step 2. Verify that the Parallel CT provides the required 3 to 5 A secondary current.

If the CT does not provide the required 3 to 5 A secondary current, refer to paragraph3-3.

If the CT does provide the required 3 to 5 A secondary current, proceed to step 3.

Step 3. Verify that the paralleling CT's polarity is correct.

If the CT's polarity is incorrect, reverse the CT secondary leads.

If the CT's polarity is correct, proceed to step 4.

Step 4. Verify that the paralleling CT is in the correct generator phase (line).

If the CT is not in the correct phase, place CT in correct line.

If the CT is in the correct phase, proceed to step 5.

Step 5. Check that all paralleled generators have the same type of sensing (either single-phaseor three-phase).

If all paralleled generators do not have the same type of sensing, adjust R25 tocompensate.

If all paralleled generators do have the same type of sensing, proceed to step 6.


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ATTACHMENT AGENERATING UNIT DATA SHEET

This sheet, when filled out at the time of installation, will save valuable time in any futureemergency as a ready reference for generator equipment specifications. Use the back of thesheet for additional data or records of maintenance.

Unit No. ______________ Location _____________________________________________

Date Installed _________ Installed by _____________________ Date in Service ________

1. ENGINE Manufactured by ________________________ Model No. ____________

Serial No. ___________________________ HP Cont. @ _________ RPM

Type: � Gas � Gasoline � Diesel � Gas Turbine � Steam Turbine

� Normally Aspirated � Supercharged � Turbosupercharged

2. GOVERNOR Manufactured by ______________________ Model No. ______________

Serial No. ___________________________ Sensing ________________

3. GENERATOR Manufactured by ______________________ Model No. ______________

Serial No. _______________________ RPM ___________Service Factor

Output : ____ KV/KVA ____CPS ____ PF ____ Volts _____ Phase ____

____ Delta ______Wye ____ Short Circuit _______ Parallel Operation

____ Number of Leads

Field: No Load______Volts _______Amps: Full-Load _____ Volts ______ Amps

Overload _____ Volts ______Amps: Resistance _____Cold______ Hot

4. EXCITER Manufactured by ___________ Model No. _________________________

Serial No. ___________________________ kW: ______________RPM

Type: � Brush Rotary � Brushless Rotary � Static

Output: No Load______Volts ______ Amps: Full-Load ______ Volts ______ Amps

Overload _____Volts ______ Amps: Resistance _____ Cold_______ Hot

5. REGULATOR Basler Electric Model _______________________ Serial No. _________

Series Boost Option Model No. __________________________________

RFI Model No. _______________________________________________

CT’s ________ PT’s _______ Parallel Operation ___________

Isolation Transformer ________

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