ABB REG650 ANSI, Technical Manual

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9.3.7.1 Measurement principle
The residual voltage is measured continuously, and compared with the set values,
U1> and U2> .
To avoid oscillations of the output START signal, a hysteresis has been included.
9.3.7.2 Time delay
9.3.7.3 Blocking
It is possible to block two step residual overvoltage protection (ROV2PTOV) partially
or completely, by binary input signals where:
BLOCK: blocks all outputs
BLKST1: blocks all startand trip outputs related to step 1
BLKST2: blocks all start and trip inputs related to step 2
9.3.7.4 Design
The voltage measuring elements continuously measure the residual voltage.
Recursive Fourier filters filter the input voltage signal. The single input voltage is
compared to the set value, and is also used for the inverse time characteristic
integration. The design of Two step residual overvoltage protection (ROV2PTOV) is
schematically described in
Figure 137 .
1MRK 502 048-UEN A
Section 9
Voltage protection
273
Technical manual