ABB RET650 Technical Manual page 233

1MRK 504 135-UEN A
Technical manual
delay in s
1800
under -
inverse delay law
excitation
overexcitation
0
M=V/Hz>
V/Hz>
IEC09000114 V1 EN
Figure 99: Restrictions imposed on inverse delays by
A definite maximum time of 1800 seconds is used to limit the operate time at low
degrees of overexcitation of V/Hz>. Inverse delays longer than 1800 seconds will not
be allowed. In case the inverse delay is longer than 1800 seconds, OEXPVPH trips
tMax, see figure 99.
A definite minimum time (tMin), can be used to limit the operate time at high degrees
of overexcitation for V/Hz>. In case the inverse delay is shorter than tMin, OEXPVPH
function trips after tMin seconds.
tMin
M - V/Hz>
Overexcitation M-V/Hz>
max
M
Excitation M
max
E (only if f = fr = const)
E
max
IEC09000114-1-en.vsd
Section 9
Voltage protection
227