Areva MiCOM P125, Technical Manual

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Application Guide P12y/EN AP/D32
MiCOM P125/P126 & P127 Page 7/74
The directional relays have been designed to provide more functionality in terms of
protections, measuring, automatic operation and order control in any medium voltage electric
network.
The specific nature of these directional relays makes it possible to apply them to various
applications, such as: medium voltage subscriber, cable line, overhead line etc. The earth
and phase protection functions include instantaneous information and time delay information.
They can operate in networks with neutral earthed by impedance, by resonant system as
such as Petersen coil, in insulated system and in system with neutral earthed.
The protection functions can be used in conjunction with blocking so as to optimise the
performance of the protection schemes, thus reducing operating times.
The delay time for the first and second stage for directional/non directional phase and earth
fault protections can be chosen to be in definite or inverse delay time (IEC, ANSI/IEEE, CO,
RI and RECT).
Instead for the wattmetric / IeCos and inverse sequence overcurrent protection, the delay
time can be chosen in definite or inverse delay time (IEC, ANSI/IEEE, CO, RI and RECT) for
the first threshold only.
This wide choice of characteristics of triggering times makes it possible to easily adapt these
directional relays to an existing protection scheme, irrespective of other relays already
installed on the network.