CURRENT SENSING - IMPROVED VOLTAGE REGULATION KIT (SC MACHINES ONLY)
The standard machine is voltage sensed and if required current sensing can be added to make the machine more flexible
to improve the voltage regulation where semi-conductor or thyristor loads are used which distort the voltage waveform of
the machine. This unit can also be used to impact on the sensing circuit of the A.V.R. to overcome voltage drops where
long cables between the generator and load are used. The unit consists of a current transformer C.T. and burden
resistor. See Fig. 20.
The components are identical to those used for the quadrature droop kit for Parallel Operation, the only difference is that
the circuit is arranged to be more sensitive between unity to 0.8 p.f. (lag) loads.
NOTES:
1. Depending on machine type, one or more main stator
cables are connected to each output terminal, insert
improved regulation C.T. on one cable only. See
Fig. 21 for C.T. position and wiring diagrams.
2. Connect to auxiliary terminals 2 - 8 (after removing
link) on two phase sensed machines and 4 - 7 (after
removing link) on three phase sensed machines.
A.V.R.
Stator Connection
Improved Voltage
Type
(Standard phase rotation)
Regulation
Fig.
C.T. Position
Two Phase
4 Wire & 6 Wire Star
20
V2
Series Star
20
V2
Sensed
12 Wire
Series Delta
20
V2
Parallel Star
20
V2
Series Zig-Zag Star
20*
W2
Three Phase
4 Wire & 6 Wire Star
20*
V2
Series Star
20*
V2
Sensed
12 Wire
Series Delta
20*
V2
Parallel Star
20*
V2
Series Zig-Zag Star
20*
U2
Fig. 21 Improved Regulation C.T. Positions
NOTES:
1. *For these stator connections the C.T. secondary leads S1 and S2 must be reversed for correct machine operation.
2. Standard phase rotation is U.V.W. when a.c. generator is rotating clockwise viewed at the drive end. For phase
rotation U.V.W. when rotating anti-clockwise refer to factory for details.
Resistance Values
Burden Resistor - 1000 ohms
C.T. Secondary - 16 ohms
39
