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CT Selection for Restricted Earth Fault protection

CT Selection for Restricted Earth Fault protection

CT Selection for Restricted Earth Fault protection

(OP)
The 6.6kV Star side of an 7.5MVA transformer is earthed through current limiting resistor to 300mA. The CT on the earthed side are 1250/1A. The phase CT on the Transformer are 800/1A. Will the mismatch on the CT ( 1250 and 800) be a problem? If not a problem how are these CT connected including the relay to show zero amps. If yes there is a problem, how can I solve it

RE: CT Selection for Restricted Earth Fault protection

Babambu,
It is not an issue if you are using a low impedence protection for REF.

RE: CT Selection for Restricted Earth Fault protection

normally numeric relays have large setting ranges. Siemens relay can matching 5A-CT secondary with 1A-CT secondary

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