Systems Operation

Usage:

Identification

SRCV GENERATOR
1. Regulator housing. 2. Bolt. 3. Exciter. 4. Bolts.

All Self Regulated Constant Voltage (SRCV) generators have an external belt driven exciter (3). It is located on the top of regulator housing (1).

The generator serial number, on the nameplate, tells four things about the generator:

1. The first group of number is the kW rating on 60 cycle generators. On 50 cycle generators it is usually one less than the kW rating.

2. The letter R is the symbol for Self Regulated Constant Voltage generator.

3. The next letter indicates the voltage rating of the generator. See Chart.

Both voltages of a (120/208) 4 wire single voltage generator can be used at the same time. On the (120-240, 200 -400 or 240-480) 10 wire dual voltage generators, the leads can be connected to get one or the other of the voltages, but not both at the same time. Rated voltage on dual voltage generators is for a line to line connection. A line to neutral connection will give 58% of the rated voltage.

NOTE: See the topic, REGULATOR CONNECTIONS in DISASSEMBLY AND ASSEMBLY for additional information on generator voltages.

4. The last group of numbers is the actual serial number of the generator in its kW and voltage rating. Serial numbers from 1 to 599 have regulators equipped with a DC Controlled Reactor. Serial numbers 600 and up have regulators equipped with a Compensating Current Transformer.

The chart that follows gives the basic characteristics of each SRCV generator.

NOTE: If a generator is connected to give performance different from that shown on the nameplate, a new nameplate should be installed on the generator. Mark the new nameplate to show the present method of connection and rated capacities.

1 60 cycle generator reworked into 50 cycle; exciter pulleys changed.

2 Radio suppressed-Bu-Docks "Deep Freeze" contract.

3 Same as 2L333 except hinged exciter.

4 Also used as single phase generator on D315 engine at 40 kW.

5 Also used as single phase generator on D315 & D315G engines at 40 kW.

6 100 kW derated to 75 kW, Radio Suppressed; Marine Corp. Contract.

7 120 Volt, 4 wire only; not reconnectable to other voltage.

8 Radio Suppressed.

9 Rewound by Hendricks Electric; also 600 series voltage regulator installed.

10 Two Bearing, clockwise rotation; rock crusher generator.

11 B100RN804 & 805 regrouped by Henricks Electric into 600 Volt.

12 Made from 4L1451 by regrouping stator into 6/3 parallel star.

13 Generator reworked by Century to physically fit D353 Engine.

14 Generator rewound by Foremost Electric.

15 Made from 3L5484 by adding stator from 4L1126 Generator and regrouping stator.

16 3L5484 Generator reworked into 120/208 volt by C.T.Co.

17 Single phase generators.

Operation Of Generators With DC Controlled Reactor Type Regulators (Serial Numbers 1-599)

WIRING DIAGRAM (TYPICAL EXAMPLE)

A. Saturable reactor.

B. Voltage droop resistor (if so equipped).

C. DC controlled reactor.

D. Voltage droop rheostat.

E. Full wave rectifier.

F. Voltage level resistor (if so equipped).

G. Blocking rectifier.

H. Voltage level rheostat.

I. Generator field.

J. Exciter armature.

K. Exciter field.

L. Exciter control field.

M. Generator armature.

Generator field (I) is connected to the engine flywheel through the generator shaft and coupling. Exciter armature (J) is belt driven from the generator shaft. Exciter field (K) is stationary and has residual magnetism. As the exciter armature turns, the coils move through the magnetic lines of flux around the exciter field. This generates an AC voltage in the exciter armature. The AC voltage is changed to DC by a commutator and brushes. The DC current flows from the brushes to generator field (I) and exciter field (K).

The current that flows to the exciter field will cause the magnetic lines of flux around exciter field (K) to get stronger. The voltage induced in the exciter armature will increase. Current flow in the exciter circuit is limited by voltage level resistor (F) and voltage level rheostat (H). The voltage level rheostat can be adjusted to control the amount of current flow in the exciter circuit. Blocking rectifier (G) prevents reverse polarity operation of the exciter.

Current flow through generator field (I) will cause magnetic lines of flux. As the generator field turns, the magnetic lines of flux move through the stationary windings of generator armature (M). This generates an AC voltage in the generator armature. Most of the AC voltage goes directly to the load. A small amount is used by the regulator circuit to control the output of the generator.

As the engine speed increases to the desired rpm, the exciter voltage increases also. This voltage is limited by the amount of field current that can flow through the resistance of voltage level resistor (F), voltage level rheostat (H), and exciter field (K). The maximum value of exciter voltage would cause so much current to flow in generator field (I) that the AC voltage induced in generator armature (M) would be more than the rated voltage.

DC CONTROLLED REACTOR TYPE REGULATOR

The regulator is used to control the exciter voltage. AC voltage from the generator armature is given to the regulator circuit at terminals 10 and 2. Full wave rectifier (E) changes the AC current to pulsating DC. This DC current then flows through exciter control field (L). The exciter field coils and the exciter control field coils are both wound on the exciter field poles. The coils are wound so that the magnetic lines of flux around one are opposite the magnetic lines of flux around the other. This is illustrated by the arrows near each coil. Because of the opposite magnetic polarities of these two fields, the effective excitation in the exciter is the difference between the magnetic fields of the two coils. A change in the amount of current flow through exciter control field (L) will cause a change in generator output voltage.

Saturable reactor (A) acts as a valve. As the load on the generator increases the voltage will decrease. The saturable reactor will let less current flow in the regulator circuit. As the current through exciter control field (L) decreases, the effective excitation in the exciter increases. This increases the generator output and the voltage will return to the desired value. As the load on the generator decreases, the voltage will increase. The saturable reactor will let more current flow in the regulator circuit. As the current flow through the exciter control field increases, the effective excitation in the exciter decreases. This decreases the generator output and the voltage will return to the desired value.

Voltage level rheostat (H) is used to adjust the voltage output of the generator to the desired value.

When the generator is to be operated in parallel with one or more other generators, it is necessary that an adjustment be made so the generator voltage will droop as load increases on the generator. The droop circuit is connected to the exciter armature. The exciter voltage causes DC current to flow in the circuit. The voltage droop adjustment is made with the voltage droop rheostat (D). When the setting of the voltage droop rheostat is moved from zero to a higher number, the resistance in the voltage droop circuit is decreased. When the voltage droop rheostat resistance is decreased, more current can flow in the droop circuit. This current flows through the center winding of DC controlled reactor (C) and changes its magnetic characteristics so there is less resistance to the flow of AC current through the outer coils. More AC current can then flow in the regulator circuit. As a result, more DC current will flow in exciter control field (L). The effective excitation in the exciter will decrease. This decreases the generator output voltage. A small load has little effect on the voltage droop circuit. Voltage droop increases as the exciter voltage increases with added load on the generator.

Operation Of Generators With Compensating Current Transformer Type Regulators (Serial Numbers 600-Up)

WIRING DIAGRAM (TYPICAL EXAMPLE)

A. Voltage droop transformer.

B. Voltage droop control switch.

C. Saturable reactor.

D. Full wave rectifier.

E. Generator armature.

F. Generator field.

G. Exciter armature.

H. Voltage level resistor (if so equipped).

I. Blocking recitifer.

J. Voltage level rheostat.

K. Exciter field.

L. Exciter control field.

Generator field (F) is connected to the engine flywheel through the generator shaft and coupling. Exciter armature (G) is belt driven from the generator shaft. Exciter field (K) is stationary and has residual magnetism. As the exciter armature turns, the coils move through the magnetic lines of flux around the exciter field. This generates an AC voltage in the exciter armature. The AC voltage is changed to DC by a commutator and brushes. The DC current flows from the brushes to generator field (F) and exciter field (K).

The current that flows to the exciter field will cause the magnetic lines of flux around exciter field (K) to get stronger. The voltage induced in the exciter armature will increase. Current flow in the exciter circuit is limited by voltage level resistor (H) and voltage level rheostat (J). The voltage level rheostat can be adjusted to control the amount of current flow in the exciter circuit. Blocking rectifier (I) prevents reverse polarity operation of the exciter.

Current flow through generator field (F) will cause magnetic lines of flux. As the generator field turns, the magnetic lines of flux move through the stationary windings of generator armature (E). This generates an AC voltage in the generator armature. Most of the AC voltage goes directly to the load. A small amount is used by the regulator circuit to control the output of the generator.

As the engine speed increases to the desired rpm, the exciter voltage increases also. This voltage is limited by the amount of field current that can flow through the resistance of voltage level resistor (H), voltage level rheostat (J) and exciter field (K). The maximum value of exciter voltage would cause so much current to flow in generator field (F) that the AC voltage induced in generator armature (E) would be more than the rated voltage.

COMPENSATING CURRENT TRANSFORMER TYPE REGULATOR

The regulator is used to control the exciter voltage. AC voltage from the generator armature is given to the regulator circuit at terminals 10 and 2. Full wave rectifier (D) changes the AC current to pulsating DC. This DC current then flows through exciter control field (L). The exciter field coils and the exciter control field coils are both wound on the exciter field poles. The coils are wound so that the magnetic lines of flux around one are opposite the magnetic lines of flux around the other. This is illustrated by the arrows near each coil. Because of the opposite magnetic polarities of these two fields, the effective excitation in the exciter is the difference between the magnetic fields of the two coils. A change in the amount of current flow through exciter control field (L) will cause a change in generator output voltage.

Saturable reactor (C) acts as a valve. As the load on the generator increases, the voltage will decrease. The saturable reactor will let less current flow in the regulator circuit. As the current through exciter control field (L) decreases, the effective excitation in the exciter increases. This increases the generator output and the voltage will return to the desired value. As the load on the generator decreases, the voltage will increase. The saturable reactor will let more current flow in the regulator circuit. As the current flow through the exciter control field increases, the effective excitation in the exciter decreases. This decreases the generator output and the voltage will return to the desired value.

Voltage level rheostat (J) is used to adjust the voltage output of the generator to the desired value.

When the generator is to be operated in parallel with one or more other generators, it is necessary that an adjustment be made so the generator voltage will droop as load increases on the generator. The AC current to the load flows through the primary of voltage droop transformer (A). This causes a voltage to be induced in the secondary of the transformer. When the setting of the voltage droop control switch is moved from zero to a higher number, a part of the induced voltage is added to the regulator circuit. Since some voltage has been added to that given by the generator at terminals 10 and 2, the current in the exciter control field will increase. The effective excitation in the exciter will decrease. This decreases the generator output voltage.