Time Delay - ABB RES670 Technical Manual

1MRK 511 408-UUS A
10.2.6.2
10.2.6.3
10.2.6.4
Phasor measurement unit RES670 2.2 ANSI
Technical manual

Time delay

The time delay for Overfrequency protection SAPTOF (81) is a settable definite time
delay, specified by the setting tDelay.
TRIP signal issuing requires that the overfrequency condition continues for at least the
user set time delay, tDelay. If the PICKUP condition, with respect to the measured
frequency ceases during this user set delay time, and is not fulfilled again within a user
defined reset time, tReset, the PICKUP output is reset, after that the defined reset time
has elapsed. It is to be noted that after leaving the hysteresis area, the PICKUP
condition must be fulfilled again and it is not sufficient for the signal to only return
back to the hysteresis area.
The total time delay consists of the set value for time delay plus
minimum trip time of the pickup function (80 - 90 ms).
Blocking
It is possible to block overfrequency protection SAPTOF (81) partially or completely,
by binary input signals or by parameter settings, where:
BLOCK: blocks the START and TRIP outputs
BLKTRIP: blocks the TRIP output
If the measured voltage level decreases below the setting of IntBlockLevel, both the
PICKUP and the TRIP outputs are blocked.
Design
The frequency measuring element continuously measures the frequency of the positive
sequence voltage and compares it to the setting PUFrequency. The frequency signal is
filtered to avoid transients due to switchings and faults in the power system. The time
integrator operates due to a definite delay time. The design of overfrequency protection
SAPTOF (81) is schematically described in figure 108.
Section 10
Frequency protection
M14958-13 v7
M14958-24 v9
M14958-9 v8
311