ABB Relion 670 series, Technical Reference Manual

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1 10
1
10
100
1000
2 40 3 4 5 20 30
TD = 2
TD = 3
TD = 4
TD = 5
TD = 6
TD = 7
TD = 8
TD = 9
TD = 10
TD = 1
OVEREXCITATION IN %
Time (s)
IEEE OVEREXCITATION CURVES
en01000373_ansi.vsd
(M-Emaxcont)*100)
TD = 60
TD = 20
ANSI01000373 V1 EN
Figure 273: Delays inversely proportional to the square of the overexcitation
The critical value of excitation M is determined indirectly 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 144 .
( )
Pickup2 f
M 1.40
Vn/fn
= =
ANSIEQUATION2286 V1 EN
(Equation 144)
The Tailor-Made law allows a user to design an arbitrary delay characteristic. In this
case the interval between M = Pickup1 , and M = Mmax is automatically divided into
Section 8
1MRK505222-UUS C
Voltage protection
536
Technical reference manual