4.8.1.2 Function block
Figure 378: Function block
4.8.1.3 Functionality
The underpower protection function DUPPDPR is used for protecting generators
and prime movers against the effects of very low power outputs or reverse power
condition.
The function operates when the measured active power falls below the set value.
The operating characteristics are according to definite time DT.
This function contains a blocking functionality. It is possible to block the function
outputs, timer or the function itself, if desired.
4.8.1.4 Operation principle
The function can be enabled and disabled with the
Operation
setting. The
corresponding parameter values are “On” and “Off”.
The operation of DUPPDPR can be described using a module diagram. All the
modules in the diagram are explained in the next sections.
Figure 379: Functional module diagram
Power calculation
This module calculates the apparent power based on the selected voltage and
current measurements as described in
Table 691
. The
Measurement mode
setting
determines which voltage and current measurements are to be used.
It is also possible to use positive-sequence components for calculating apparent
power, which makes the determination of power insensitive to the possible
1MRS757644 H
Protection functions
620 series
Technical Manual
729
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