ABB Relion 620 Series - Page 455

4.2.5.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Rotor earth-fault protection MREFPTOC Io>R 64R
4.2.5.2 Function block
Figure 230: Function block
4.2.5.3 Functionality
The rotor earth-fault protection function MREFPTOC is used to detect an earth
fault in the rotor circuit of synchronous machines. MREFPTOC is used with the
injection device REK510, which requires a secured 58, 100 or 230 V AC 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.
4.2.5.4 Operation principle
The function can be enabled and disabled with the
Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of MREFPTOC can be described using a module diagram. All the
modules in the diagram are explained in the next sections.
Figure 231: Functional module diagram
1MRS757644 H
Protection functions
620 series
Technical Manual
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