Design - ABB RES670 Technical Manual

Relion 670 series, phasor measurement unit

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Frequency protection

blocks the START and TRIP outputs

blocks the TRIP output

blocks the RESTORE output

If the measured voltage level decreases below the setting of IntBlockLevel, both the

PICKUP and the TRIP outputs are blocked.

Design

Rate-of-change frequency protection (SAPFRC, 81) measuring element continuously

measures the frequency of the selected voltage and compares it to the setting

PUFreqGrad. The frequency signal is filtered to avoid transients due to power system

switchings and faults. The time integrator operates with a definite delay time. When

the frequency has returned back to the setting of RestoreFreq, the RESTORE output is

issued after the time delay tRestore, if the TRIP signal has earlier been issued. The sign

of the setting PUFreqGrad is essential, and controls if the function is used for raising

or lowering frequency conditions. The design of SAPFRC (81) is schematically

described in figure 110.

1MRK 511 408-UUS A

Phasor measurement unit RES670 2.2 ANSI

Technical manual

M14970-34 v7

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