Ct/Vt Modules - GE G30 Instruction Manual

3.2 WIRING
An LED on the front of the control power module shows the status of the power supply:
LED INDICATION
CONTINUOUS ON
ON / OFF CYCLING
OFF
3
A CT/VT module can have voltage or current inputs on channels 1 through 4 inclusive, or channels 5 through 8 inclusive.
Channels 1 and 5 are intended for connection to phase A, and are labeled as such in the relay. Likewise, channels 2 and 6
are intended for connection to phase B, and channels 3 and 7 are intended for connection to phase C.
Channels 4 and 8 are intended for connection to a single-phase source. For voltage inputs, these channel are labelled as
auxiliary voltage (VX). For current inputs, these channels are intended for connection to a CT between system neutral and
ground, and are labelled as ground current (IG).
To connect the module, size 12 American Wire Gauge (AWG) is commonly used; the maximum size is 10 AWG.
CT/VT modules can be ordered with a standard ground current input that is the same as the phase current input. Each AC
current input has an isolating transformer and an automatic shorting mechanism that shorts the input when the module is
withdrawn from the chassis. There are no internal ground connections on the current inputs. Current transformers with 1 to
50000 A primaries and 1 A or 5 A secondaries can be used.
CT/VT modules with a sensitive ground input are also available. The ground CT input of the sensitive ground modules is 10
times more sensitive than the ground CT input of standard CT/VT modules. However, the phase CT inputs and phase VT
inputs are the same as those of regular CT/VT modules.
The above modules have enhanced diagnostics that can automatically detect CT/VT hardware failure and take the relay
out of service.
CT connections for both ABC and ACB phase rotations are identical as shown in the Typical wiring diagram.
The exact placement of a zero-sequence core balance CT to detect ground fault current is shown as follows. Twisted-pair
cabling on the zero-sequence CT is recommended.
3-12
POWER SUPPLY
OK
Failure
Failure
Figure 3–13: CONTROL POWER CONNECTION
Verify that the connection made to the relay terminals for nominal current of 1 A or 5 A matches the
secondary rating of the connected CTs. Unmatched CTs can result in equipment damage or inade-
quate protection.
G30 Generator Protection System
3 HARDWARE

3.2.4 CT/VT MODULES

GE Multilin