Protection Engineering Basics and Schemes Protection Engineering | Page 202

6.3.1.2 Differential Protection- Pilot:
The distance between substations will be in kilometers,
Let suppose our grid is at A, and our main substation is
from Distance B km from A, and we need to protection
the load busbar or cable between the substations, then
we commissioned differential relays on each substations
and connect both differential relays via pilot wire and
any other communication mode.
We also use interposing Current transformer here, these
ICTs will reduce main CTs secondary current of 1 A or 5 A
to mille amperes. Aim is to reduce burdens on pilot wires
or communication channels.
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