ABB Relion 670 Series Technical Reference Manual page 526

Line differential protection ansi

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Voltage protection

EQUATION1616 V1 EN

When the denominator in the expression is equal to zero the time delay will be infinity.

There will be an undesired discontinuity. Therefore a tuning parameter CrvSatn is set

to compensate for this phenomenon. In the voltage interval Vpickup up to Vpickup ·

(1.0 + CrvSatn/100) the used voltage will be: Vpickup · (1.0 + CrvSatn/100). If the

programmable curve is used this parameter must be calculated so that:

EQUATION1440 V1 EN

The details of the different inverse time characteristics are shown in section

characteristics".

TRIP signal issuing requires that the residual overvoltage condition continues for at

least the user set time delay. This time delay is set by the parameter t1 and t2 for

definite time mode (DT) and by 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, and is not fulfilled again within a user defined reset time (tReset1 and tReset2 for

the definite time and tIReset1 and tIReset2 for the inverse time) the corresponding

PICKUP output is reset, after that the defined reset time has elapsed.

Here it should 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. Also notice that for the overvoltage function TOV reset time is

constant and does not depend on the voltage fluctuations during the drop-off period.

However, there are three ways to reset the timer, either the timer is reset

instantaneously, or the timer value is frozen during the reset time, or the timer value is

linearly decreased during the reset time. See figure

1MRK505222-UUS C

and figure 259.

Technical reference manual

(Equation 133)

(Equation 134)

Relion red670