ABB Relion Technical Manual page 312

Section 9
Voltage protection
306
Time (s)
1000
100
10
1
1 2 3
ANSI01000373 V1 EN
Figure 140: Delays inversely proportional to the square of the overexcitation
The critical value of excitation M is determined via OEXPVPH (24) setting Pickup2.
Pickup2 can be thought of as a no-load voltage at rated frequency, where the inverse law
should be replaced by a short definite delay, t_MinTripDelay. If, for example, Pickup2 =
140 %, then M is according to equation 91.
( )
Pickup2 f
= =
M 1.40
Vn/fn
ANSIEQUATION2286 V1 EN
IEEE OVEREXCITATION CURVES
4 5 10
OVEREXCITATION IN %
1MRK 502 048-UUS A
TD = 60
TD = 20
TD = 10
TD = 9
TD = 8
TD = 7
TD = 6
TD = 5
TD = 4
TD = 3
TD = 2
TD = 1
20 30 40
(M-Emaxcont)*100)
en01000373_ansi.vsd
(Equation 91)
Technical manual