INSTRUCTION MANUAL - gen-powercontrols.com

1 INSTRUCTION MANUALFORVOLTAGE REGULATORM odel: SR32 APart Number: 9 0750 00 104 Publication Number: 9 0750 00 990 Date: January, 1979 Revision G: March, 19971-1 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 SPECIFICATIONSR efer to Table 1-1 for the electrical specifications and to Table 1-2 for the physical 1-1. Electrical Voltage60 volts; if correct input voltage is not available, a suitablepower transformer must be :50 Hz, 60 Amps:1200; when regulator is operated at less than maximum output,power isolation transformer rating can be determined bymultiplying input volts by DC output ContinuousOutput:32 volts, 20 1-Minute Forcing:45 volts, 28 voltage :NEMA Standard 120, 208, 240, 416, 480, 600; single phase orthree Burden PerPhase:10 Compensation:5A input, 25 VA burden, droop adjustable to approximately 5%.

2 Field ohms Accuracy:Within + over full range of alternator Response:Less than 17 Drift:Less than + per 104 F (40 C) ambient Sensing:Single-phase or Dissipation:Less than 170 watts at continuous Adjust Range:Minimum +10% of nominal 1 GENERAL INFORMATION1-1. INTRODUCTION1-2 Table 1-2. Physical Dimensions:13 inches (330 mm) X inches (217 mm) X inches(183 mm).Weight:Net 18 lbs. ( kg); shipping 20 lbs. ( kg).Finish:Dark brown, lusterless, textured, baked OperatingTemperature Range:-55 C to +70 C (-67 F to + 158 F) without TemperatureRange:-65 C to +100 C (-85 F to +212 F) without degradation :Withstands up to 5 G s at 260 :Withstands up to 15 G 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.

3 Table 1-3 lists all available features along with the model number designatorfor Parallel compensation is controlled by either an internal adjustable resistor or an Single or three-phase sensing with NEMA standard Internal or external voltage -adjust Stabilizing networks for use with brush or brushless rotary exciters or as a static OPTIONAL FEATURES1-3 Figure 1-1. Sample Model NumberTable 1-3. Model Number Style Model relayB-Build-upRelayC-Hermeticallysealed , useas usewithbrushlessexciter(primarilyongener atorsrated 150kW orless) orwith BUILD-UP PROVISIONSPARALLEL PROVISIONSSINGLE- OR THREE-PHASE SENSINGENCLOSURETYPE OF voltage ADJUSTMENTTYPE OF STABILITY CIRCUITSR32A2B15B3 MOUNTINGBD2589-0102-24-971-4 Accessories are not designated in the SR model number and must be selected as separateitems.

4 Available accessories include the following:1. Power transformers2 Paralleling current transformers3 Exictation Support Systems (Series Boost Options).4 Underfrequency - Overvoltage Control Modules5 MANUAL voltage Control Module6SR Regulator with RFI Suppression7 Motor Operated Potentiometer8 Wide Range voltage Adjust9 Volts-Per-Cycle Modules10 DC Generator voltage Control11. VAR/Power Factor ControllerInformation 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 ACCESSORIES2-1 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.

5 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 2-1. Input Phase 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 .

6 A minimum 3V generator residualis required for automatic voltage buildup. If residual is less than 3V, external field flashing maybe 2 THEORY OF OPERATION2-1. FUNCTIONAL CIRCUIT2-2. AUTOMATIC voltage BUILDUP2-2In 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 ,316,479, prevents collapse of excitation by providing constant voltage to the regulator for alloperating 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 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.

7 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.

8 (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 .

9 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 field2-3. MOTOR STARTING OR SHORT CIRCUIT OPERATION2-4. PARALLEL OPERATION2-3current 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.

10 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 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.