EMR-5000
IM02602012E
LOP - Loss of Potential
Available elements:
LOP
Do not use the LOP element in combination with undelayed undervoltage protection (ANSI
27) to prevent faulty tripping.
LOP function detects the loss of voltage in any of the voltage input measuring circuits and uses the following measured
values and information to detect an LOP condition:
•
Three-phase voltages;
•
Ratio of negative-to-positive sequence voltages;
•
Zero sequence voltage;
•
Three-phase currents;
•
Residual current (I0);
•
Pickup flags from all instantaneous phase and earth overcurrent elements; and
•
Breaker status
Once an LOP condition is detected and it lasts longer than an adjustable minimum pickup time, the LOP Pickup will be
set. The LOP Block will only be set if the LOP-Block control setting is set to enabled (activated). The LOP Pickup and
LOP Block signals can both be used as logical signal to block the protective functions which use the voltage information
such as voltage restraint. The minimum pickup timer is used to prevent short time incorrect operation of the LOP
function during breaker switching-on operation.
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