Technical Data
4.7 Differential Protection (ANSI 87G/87M) for Generators and Motors
SIPROTEC, 7UM62, Manual
C53000-G1176-C149-7, Release date 03.2010
477
Influencing Variables for Pickup Values
Figure 4-6 Pickup Characteristic for Use as Generator or Motor Differential Protection
Figure 4-7 Influence of Frequency in Generator or Motor Differential Protection
where:
I
DIFF
Differential current = |I
1
+ I
2
|
I
NObj
Nominal current of the protected object
I
Xf
Current at any frequency within specified range
Power supply direct voltage in range 0.8 ≤ U
Aux
/U
AuxN
≤ 1.15 ≤ 1 %
Temperature in range 23.00 °F (–5 °C) ≤ Θ
amb
≤ 131.00 °F (55 °C) ≤ 0.5 % / 10 K
Frequency in range 0.95 ≤ f/f
N
≤ 1.05 ≤ 1 % (see also Figure 4-7)
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