ABB Relion 650 Series Technical Manual page 243

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1MRK 506 326-UUS B

Trip signal issuing requires that the undervoltage condition continues for at least the user set

time delay. This time delay is set by the parameter

some special voltage level dependent time curves for the inverse time mode (TOV). If the pickup

condition, with respect to the measured voltage ceases during the delay time, the corresponding

pickup output is reset.

It is possible to block Two step undervoltage protection (UV2PTUV ,27) partially or completely, by

binary input signals or by parameter settings, where:

The voltage measuring elements continuously measure the three phase-to-neutral voltages or the

three phase-to-phase voltages. Recursive fourier filters or true RMS filters of input voltage signals

are used. The voltages are individually compared to the set value, and the lowest voltage is used

for the inverse time characteristic integration. A special logic is included to achieve the

out of 3 and 3 out of 3 criteria to fulfill the PICKUP condition. The design of Two step undervoltage

protection UV2PTUV (27) is schematically shown in

Line distance protection REL650

Technical manual

blocks all outputs

blocks all pickup and trip outputs related to step 1

blocks all pickup and trip outputs related to step 2

t1 and t2 for definite time mode (DT) and by

Voltage protection

M15326-20 v5

M15326-35 v5

1 out of 3 , 2