ABB Relion REG670, Техническое руководство

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A definite minimum time, tMin , can be used to limit the operate time at high degrees
of overexcitation. In case the inverse delay is shorter than tMin , OEXPVPH function
trips after tMin seconds. The inverse delay law is not valid for values exceeding
Mmax. The delay will be tMin, irrespective of the overexcitation level, when values
exceed Mmax (that is, M>
V/Hz> ).
1 10
1
10
100
1000
2 40 3 4 5 20 30
k = 2
k = 3
k = 4
k = 5
k = 6
k = 7
k = 8
k = 9
k = 10
k = 20
k = 60
k = 1
OVEREXCITATION IN %
Time (s)
IEEE OVEREXCITATION CURVES
en01000373.vsd
(M-Emaxcont)*100)
IEC01000373 V1 EN
Figure 251: Delays inversely proportional to the square of the overexcitation
The critical value of excitation M is determined indirectly via OEXPVPH setting V/
Hz>> . V/Hz>> can be thought of as a no-load voltage at rated frequency, where the
inverse law should be replaced by a short definite delay, tMin . If, for example, V/
Hz>> = 140 %, then M is according to equation 131 .
( )
V Hz>> / f
M 1.40
Ur/fr
= =
IECEQUATION2286 V1 EN
(Equation 131)
Section 9
1MRK502052-UEN B
Voltage protection
524
Technical manual