109
Two step definite and inverse time-
delayed residual
overcurrent protection (TEF1 and TEF2)
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The change in operate value is small when the phase angle deviates moderately from
65°. A deviation of 20° increases the operate value by only 6.5%.
The polarizing voltage can have a high content of harmonics relative to the fundamental
frequency when the output voltage is low, particularly when capacitive VTs are used.
To secure a correct measurement, the directional function must have an effective band-
pass filtering of the voltage. In the module, the filtering secures a correct function for
fundamental frequency polarizing voltages down to 1% of the rated voltage.
The directional function has two comparators, one operates in the forward direction
(STFW) and one operates in the reverse direction (STRV). In case of an external fault,
the capacitive current generated on the line decreases the current to the earth-fault relay
situated at the line end towards the fault. So the reverse direction comparator must have
an increased sensitivity to secure reliable blocking in case of external faults when a di-
rectional comparison or a blocking communication scheme is used. The operate current
of the reverse direction measuring element in the module is, as a fixed ratio, set at 0.6
IN> Dir.
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IN Operation
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Summary of Contents for REO 517
Page 10: ... RQWHQWV ...
Page 16: ...6 Introduction to the application manual KDSWHU QWURGXFWLRQ ...
Page 64: ...54 Blocking of signals during test KDSWHU RPPRQ IXQFWLRQV ...
Page 88: ...78 Scheme communication logic ZCOM KDSWHU LQH LPSHGDQFH ...
Page 146: ...136 Unbalance protection for capacitor banks TOCC KDSWHU XUUHQW ...
Page 166: ...156 Dead line detection DLD KDSWHU 3RZHU V VWHP VXSHUYLVLRQ ...
Page 378: ...368 Monitoring of DC analog measurements KDSWHU 0RQLWRULQJ ...
Page 384: ...374 Pulse counter logic PC KDSWHU 0HWHULQJ ...
Page 412: ...402 Serial communication modules SCM KDSWHU DWD FRPPXQLFDWLRQ ...
Page 440: ...430 LED indication module KDSWHU DUGZDUH PRGXOHV ...