Ct Supervision (60Cts-I & Cts); 60Cts-I; Figure 5.3.1-1 Logic Diagram: Ct Supervision Function (60Cts-I) - Siemens 7SR18 Solkor Manual

5.3 CT Supervision (60CTS-I & CTS)
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.
5.3.1

60CTS-I

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-I Delay then a CT failure output
(60CTS Operated) is given. If all three input currents fall below the setting, CT failure is not raised.
An output is also given to indicate the faulted phase, 60CTS-I PhA, 60CTS-I PhB, and 60CTS-I PhC
Operation of the CT supervision elements can be inhibited from:
Inhibit 60CTS-I
60CTS-I Element
Enabled
Disabled
Inhibit 60CTS-I
60CTS I-I
<
IL1
IL2
Any 2 phases
but not all 3
IL3
Unrestricted ©2018 Siemens Protection Devices Limited
A binary or virtual input.
&

Figure 5.3.1-1 Logic Diagram: CT Supervision Function (60CTS-I)

60CTS-I Delay
&
7SR18 Description Of Operation
60CTS-I Operated
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