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89
Time delayed phase and residual
overcurrent protection (TOC1)
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In case of extremely short or not fully transposed parallel lines, the false residual current
must be measured or calculated when maximum sensitivity is desired. The residual cur-
rent is proportional to the load current.
General criteria for the primary current setting value of the time delayed residual over-
current protection is given in the formula below:
(Equation 34)
The residual protection must not operate under any high load conditions. If the system
is in a stressed situation due to loss of some parallel line the observed line must not be
tripped due to increased residual current caused by load current increase.
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If Is is the primary setting operating value of the function, then the secondary setting
current (Is
SEC
) is:
(Equation 35)
where I
SEC
is the secondary rated current of the main CT and I
PRIM
is the primary rated
current of the main CT.
The relay setting value is given in percentage of the secondary base current value, I
1b
,
associated to the current transformer input I1. The value for IP> and IN> is given from
the formula:
Where:
IRmax
is the maximum permissive residual current flowing in the protection unit
during any service conditions and
Ifmin
is the minimum residual fault current that the relay has to clear.
1.3
and
0.7
are safety factor values.
1.3 IRmax
⋅
Is
0.7 If min
⋅
<
<
Is
SEC
I
S EC
I
PRIM
--------------
Is
⋅
=
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 ...