ABB 650 series, Technical Manual

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adding the input phase voltages. 3V
0
may also be input single phase by either measuring
directly from a voltage transformer in the neutral of a power transformer, or from a
secondary broken delta connection of a transformer with a wye-grounded primary.
ROV2PTOV (59N) has two steps with separate time delays. If the ground overvoltage
remains above the set value for a time period corresponding to the chosen time delay, the
corresponding TRIP signal is issued.
The time delay characteristic is setable for step 1 and can be either definite or inverse time
delayed. Step 2 is always definite time delayed.
The voltage related settings are made in percent of the global phase-to-phase base voltage
divided by √3.
9.3.7.1 Measurement principle
The residual voltage is measured continuously, and compared with the set values, Pickup1
and Pickup2 .
To avoid oscillations of the output PICKUP 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, 59N)
partially or completely, by binary input signals where:
BLOCK: blocks all outputs
BLK1: blocks all pickupand trip outputs related to step 1
BLK2: blocks all pickup 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, 59N) is schematically described
in
Figure 137 .
1MRK 502 048-UUS A
Section 9
Voltage protection
297
Technical manual