4.8.4.2 Function block
Figure 602: Function block
4.8.4.3 Functionality
The under power factor function MPUPF is used to provide out-of-step and loss of,
or under excitation protection for small synchronous motors and generators. The
function calculates the power factor and uses a threshold of under power factor as
an indication of an out-of-step and/or loss of excitation condition.
In addition, the function can be applied as a power factor controller.
The function contains a blocking functionality. It is possible to block function
outputs, timers or the function itself.
4.8.4.4 Analog channel configuration
MPUPF has two analog group inputs which must be properly configured.
Table 1018: 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 1019: Special conditions
Condition Description
U3P connected to real meas-
urements
The function requires that any two voltage channels are con-
nected.
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.
4.8.4.5 Operation principle
The function can be enabled and disabled with the
Operation
setting. The
corresponding parameter values are "on" and "off".
1MRS759142 F
Protection functions
REX640
Technical Manual
1079
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