Functions
2.16 Underexcitation (Loss-of-Field) Protection (ANSI 40)
SIPROTEC, 7UM62, Manual
C53000-G1176-C149-7, Release date 03.2010
138
Undervoltage Blocking
The admittance calculation requires a minimum measurement voltage. During a severe collapse (short-circuit)
or failure of stator voltages, the protection is blocked by an integrated AC voltage monitor whose pickup thresh-
old 3014 Umin is set on delivery to 25 V. The parameter value is based on phase-to-phase voltages.
The following figure shows the logic diagram for underexcitation protection.
Figure 2-55 Logic diagram of the Underexcitation Protection
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