50/60 Hz input source and injects a 100 V AC voltage via its coupling capacitors to
the rotor circuit towards earth.
MREFPTOC consists of independent alarm and operating stages. The operating
time characteristic is according to definite time (DT) for both stages.
MREFPTOC contains a blocking functionality. It is possible to block function
outputs, timers or the function itself.
4.2.5.4 Analog channel configuration
MREFPTOC has one analog group input which must be properly configured.
Table 575: Analog signals
Input Description
IRES Residual current (measured or calculated)
See the preprocessing function blocks in this document for the possible
signal sources.
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.
4.2.5.5 Operation principle
The function can be enabled and disabled with the
Operation
setting. The
corresponding parameter values are "on" and "off".
The operation of MREFPTOC can be described using a module diagram. All the
modules in the diagram are explained in the next sections.
Level
detector 1
IRES
BLOCK
OPERATE
Io
ALARM
Level
detector 2
START
Timer 2
t
Timer 1
t
Figure 297: Functional module diagram
Protection functions
1MRS759142 F
516 REX640
Technical Manual
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