Operation Principle - ABB RELION 620 Series Technical Manual

Section 4
Protection functions
4.2.1.4
268
59 includes both definite time (DT) and inverse definite minimum time (IDMT)
characteristics for the delay of the trip.
The function contains a blocking functionality. It is possible to block function outputs,
timer or the function itself, if desired.

Operation principle

The function can be enabled and disabled with the Operation setting. The corresponding
parameter values are "Enable" and "Disable".
The operation of the three-phase overvoltage protection can be described using a module
diagram. All the modules in the diagram are explained in the next sections.
GUID-0C80D68A-9D22-47C6-8AAA-8E0D639764D9-ANSI V2 EN
Figure 123: Functional module diagram
Level detector
The fundamental frequency component of the measured three-phase voltages are
compared phase-wise to the set value of the Pickup value setting. If the measured value is
higher than the set value of the Pickup value setting, the level detector enables the phase
selection logic module. The Relative hysteresis setting can be used for preventing
unnecessary oscillations if the input signal slightly differs from the Pickup value setting.
After leaving the hysteresis area, the pickup condition has to be fulfilled again and it is not
sufficient for the signal to only return to the hysteresis area.
The Voltage selection setting is used for selecting phase-to-ground or phase-to-phase
voltages for protection.
For the voltage IDMT operation mode, the used IDMT curve equations contain
discontinuity characteristics. The Curve Sat relative setting is used for preventing
undesired operation.
1MAC504801-IB E
620 series ANSI
Technical Manual