4.2.8.2
Function block
Figure 246: Function block
4.2.8.3
Functionality
The multifrequency admittance-based earth-fault protection function MFADPSDE
provides selective directional earth-fault protection for high-impedance earthed
networks, that is, for compensated, unearthed and high resistance earthed
systems. It can be applied for the earth-fault protection of overhead lines and
underground cables.
The operation of MFADPSDE is based on multifrequency neutral admittance
measurement, utilizing cumulative phasor summing technique. This concept
provides extremely secure, dependable and selective earth-fault protection also
in cases where the residual quantities are highly distorted and contain non-
fundamental frequency components.
The sensitivity that can be achieved is comparable with traditional fundamental
frequency based methods such as IoCos/IoSin (DEFxPDEF), Watt/Varmetric
(WPWDE) and neutral admittance (EFPADM).
MFADPSDE is capable of detecting faults with dominantly fundamental frequency
content as well as transient, intermittent and restriking earth faults. MFADPSDE can
be used as an alternative solution to transient or intermittent function INTRPTEF.
MFADPSDE supports fault direction indication both in operate and non-operate
direction, which may be utilized during fault location process. The inbuilt transient
detector can be used to identify restriking or intermittent earth faults, and
discriminate them from permanent or continuous earth faults.
The operation characteristic is defined by a tilted operation sector, which is
universally valid for unearthed and compensated networks.
The operating time characteristic is according to the definite time (DT).
The function contains a blocking functionality to block function outputs, timers or
the function itself.
4.2.8.4
Operation principle
The function can be enabled and disabled with the
Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of MFADPSDE can be described using a module diagram. All the
modules in the diagram are explained in the following sections.
1MRS757644 H
Protection functions
620 series
Technical Manual
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