ABB RELION REX640 Technical Manual page 570

Protection and control

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Protection functions

The START output is activated once

is activated once

are valid. Reset timer is started if any of the above three conditions is not

valid. If the fault is transient and self-extinguishes, START output stays activated

until the elapse of reset timer (setting Reset delay time). After OPERATE output

activation, START and OPERATE outputs are reset immediately, if any of the above

three conditions is not valid. The start duration value START_DUR, available in the

Monitored data view, indicates the percentage ratio of the start situation and the

set operating time.

Operate delay time has elapsed and the above three conditions

If detection of temporary earth faults is not desired, the activation of

START output can be delayed with setting

setting can also be used to avoid restarting of the function during long

lasting post-fault oscillations, if time constant of post-fault oscillations is

very long (network losses and damping is low).

To keep the operate timer activated between current spikes during

intermittent or restriking earth fault, the

to a value exceeding the maximum expected time interval between fault

spikes (obtained at full resonance condition). Recommended value is at

least 300 ms.

Start delay time has elapsed. OPERATE output

Start delay time . The same

Reset delay time should be set

1MRS759142 F

Technical Manual