The protection uses two impedance measurement elements known as inner and
outer blinders on mho characteristics with a timer. The function calculates the
impedance. If the measured impedance stays between inner and outer blinder for
a predetermined time and moves farther inside the inner blinder, then an out of
step condition is indicated. Operate is generated if out of step is indicated and
impedance moves out of mho characteristics. The mho characteristic can be divided
into two zones so separate trips can be generated based on the zone. Operating
can also be selected to occur when the impedance is on the way into the zone or for
when the impedance is on the way out of the zone.
The function contains a blocking functionality. It is possible to block function
outputs, the definite timer or the function itself.
4.7.2.4
Analog channel configuration
OOSRPSB has two analog group inputs which must be properly configured.
Table 935: Analog inputs
Input
Description
I3P
Three-phase currents
U3P
Three-phase voltages
See the preprocessing function blocks in this document for the possible
signal sources.
There are a few special conditions which must be noted with the configuration.
Table 936: Special conditions
Condition
Description
U3P connected to real measurements
The function can work with any two voltage
channels connected but it is recommended
to connect all three voltage channels.
Improper analog channel configuration causes a validation error if the analog
channels are not completely configured or they do not match with certain settings.
For troubleshooting, check the contents of this chapter and also the preprocessing
blocks in this document. The configuration can be written to the protection relay
once the mismatch is corrected.
4.7.2.5
Operation principle
The function can be enabled and disabled with the
Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of OOSRPSB can be described using a module diagram. All the
modules in the diagram are explained in the next sections.
Protection functions
1MRS759142 F
1006
REX640
Technical Manual