4.2.1.3
Functionality
The non-directional earth-fault protection function EFxPTOC is used as non-
directional earth-fault protection for feeders.
The function starts and operates when the residual current exceeds the set limit.
The operate time characteristic for low stage EFLPTOC and high stage EFHPTOC
can be selected to be either definite time (DT) or inverse definite minimum
time (IDMT). The instantaneous stage EFIPTOC always operates with the DT
characteristic.
In the DT mode, the function operates after a predefined operate time and resets
when the fault current disappears. The IDMT mode provides current-dependent
timer characteristics.
The function contains a blocking functionality. It is possible to block function
outputs, timers or the function itself.
4.2.1.4
Analog channel configuration
EFxPTOC has one analog group input which must be properly configured.
Table 502: Analog inputs
Input
Description
IRES
Residual current (measured or calculated)
See the preprocessing function blocks in this document for the possible
signal sources.
Improper analog channel configuration causes a validation error if the analog
channels are not completely configured or they do not match with certain settings.
For troubleshooting, check the contents of this chapter and also the preprocessing
blocks in this document. The configuration can be written to the protection relay
once the mismatch is corrected.
4.2.1.5
Operation principle
The function can be enabled and disabled with the
Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of EFxPTOC can be described by using a module diagram. All the
modules in the diagram are explained in the next sections.
1MRS759142 F
Protection functions
REX640
Technical Manual
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