ABB Relion REG670, Applications Manual

Page: 173 / 780

As seen in the setting examples above the sensitivity of HZPDIF function is normally
high, which means that the function will in many cases operate also for short circuits
or open current transformer secondary circuits. However the stabilizing resistor can
be selected to achieve sensitivity higher than normal load current and/or separate
criteria can be added to the operation, like a check zone. This can be either another
IED, with the same HZPDIF function, or be a check about the fault condition, which
is performed by an earth overcurrent function or neutral point voltage function.
For such cases where operation is not expected during normal service the alarm output
should be used to activate an external shorting of the differential circuit avoiding
continuous high voltage in the circuit. A time delay of a few seconds is used before the
shorting and alarm are activated. Auxiliary relays with contacts that can withstand
high voltage shall be used, like RXMVB types.
The metrosil operating characteristic is given in the following figure.
IEC05000749 V1 EN
Figure 66: Current voltage characteristics for the non-linear resistors, in the range 10-200 V, the average
range of current is: 0.01–10 mA
7.3 Generator differential protection GENPDIF
7.3.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Generator differential protection GENPDIF
I
d
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SYMBOL-NN V1 EN
87G
1MRK 502 071-UEN -
Section 7
Differential protection
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062 167
Application manual