85
Time delayed phase and residual
overcurrent protection (TOC1)
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The definite time-delayed protection TOC1 is intended for single and two-phase system
with a rated frequency of 16 2/3, 50 or 60 Hz.
The time delayed phase overcurrent protection is non-directional and can be used as in-
dependent overcurrent protection, particularly for radially fed systems, or as back-up
function to the main distance protection. In the first case the protected zone of the time
delayed overcurrent protection reaches up to the next overcurrent protection and works
in its zone as back-up protection. The programmable time delay (definite time) of the
function allows the time selectivity through an appropriate time grading among the
overcurrent relays protecting the system.
Where the function acts as back-up for the main line protection, the trip from the over-
current protection can be activated when the main protection function is blocked (e.g.
by the fuse failure protection) or it can be active all the time.
In some cases, where it could be difficult to achieve a selective trip, the function can be
used as a helpful overcurrent signalization for the post-fault analysis.
The time delayed residual current function, IN> (earth-fault protection), serves as a lo-
cal back-up function to the main protection function. In most cases, it is used as a back-
up for the earth-fault measuring in distance protection.
The IN> function is intended to be used in solidly earthed two-phase systems.
The time delay makes it possible to set the relay to detect high resistance faults and still
perform selective trip.
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The current measuring element in one of the integrated signal processors continuously
measures the phase currents (IL1 and IL2) and the residual current (IN) in two-phase
systems. In single-phase systems it measures the line current IL1. The measured cur-
rents are compared with the set operate values I> and IN>. A recursive Fourier filter
filters the current signals, and a separate trip counter prevents high overreaching of the
measuring elements. The logical value of the current signal on the output of the digital
processor is equal to 1 if the measured current exceeds the set value.
Содержание REO 517
Страница 10: ... RQWHQWV ...
Страница 16: ...6 Introduction to the application manual KDSWHU QWURGXFWLRQ ...
Страница 64: ...54 Blocking of signals during test KDSWHU RPPRQ IXQFWLRQV ...
Страница 88: ...78 Scheme communication logic ZCOM KDSWHU LQH LPSHGDQFH ...
Страница 100: ...90 Time delayed phase and residual overcurrent protection TOC1 KDSWHU XUUHQW Equation 36 Iset IsSEC I1b 100 ...
Страница 146: ...136 Unbalance protection for capacitor banks TOCC KDSWHU XUUHQW ...
Страница 166: ...156 Dead line detection DLD KDSWHU 3RZHU V VWHP VXSHUYLVLRQ ...
Страница 171: ...161 About this chapter KDSWHU RQWURO KDSWHU RQWURO ERXW WKLV FKDSWHU This chapter describes the control functions ...
Страница 293: ...283 About this chapter KDSWHU RJLF KDSWHU RJLF ERXW WKLV FKDSWHU This chapter describes the logic functions ...
Страница 378: ...368 Monitoring of DC analog measurements KDSWHU 0RQLWRULQJ ...
Страница 379: ...369 About this chapter KDSWHU 0HWHULQJ KDSWHU 0HWHULQJ ERXW WKLV FKDSWHU This chapter describes the metering functions ...
Страница 384: ...374 Pulse counter logic PC KDSWHU 0HWHULQJ ...
Страница 412: ...402 Serial communication modules SCM KDSWHU DWD FRPPXQLFDWLRQ ...
Страница 440: ...430 LED indication module KDSWHU DUGZDUH PRGXOHV ...