7PG2113/4/5/6 Solkor Description of Operation
6.3
CT Supervision (60CTS)
The relay has two methods of detecting a CT failure, depending on the relay model. CT Supervision is only
available in relays with four current inputs.
6.3.1 60CTS – 7PG2113/5
The current from each of the Phase Current Transformers is monitored. If one or two of the three input currents
falls below the CT supervision current setting
CTS I
for more than
60CTS Delay
then a CT failure output (
60CTS
Operated
) is given. If all three input currents fall below the setting, CT failure is not raised.
Operation of the CT supervision elements can be inhibited from:
Inhibit 60CTS
A binary or virtual input.
Figure 6.3-1 Logic Diagram: CT Supervision Function (60CTS) – 7PG2113/5
6.3.2 60CTS – 7PG2114/6
Normally the presence of negative phase sequence (NPS) current in a power system is accompanied by NPS
voltage. The presence of NPS current without NPS voltage is used to indicate a current transformer failure.
The element has a setting for NPS current level
60CTS Inps
and a setting for NPS voltage level
60CTS Vnps
If
the negative sequence current exceeds its setting while the negative sequence voltage is below its setting for
more than
60CTS Delay
then a CT failure output (
60CTS Operated
) is given.
Operation of the CT supervision elements can be inhibited from:
Inhibit 60CTS
A binary or virtual input.
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