Ct/Vt Modules - GE N60 Instruction Manual

WIRING
An LED on the front of the control power module shows the status of the power supply, as outlined in the table.
Table 3-2: Power supply LED on front panel
LED indication
Continuous on
On/off cycling
Off
3

3.3.4 CT/VT modules

The CT and VT inputs are analog current transformer and voltage transformer signals used to monitor AC power lines. The
UR-series relays support 1 A and 5 A CTs.
A CT/VT module can have current or voltage 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 channels are labeled 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 used commonly; 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withdrawn from the chassis.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.
These 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.
3-8
Power supply
OK
Failure
Failure or no power
Figure 3-6: 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
inadequate protection.
N60 NETWORK STABILITY AND SYNCHROPHASOR MEASUREMENT SYSTEM – INSTRUCTION MANUAL
CHAPTER 3: INSTALLATION