Operation Manual 37107F
MFR 3 - Multi Function Relay
© Woodward
Page 67/165
Parameter
23
Voltage system
----------------
This screen only affects the dis-
play. The watchdog screens are
defined further below.
Voltage measuring system threephase/singlephase
Three-phase network
The electrical system (generator, busbar, and mains) is a
delta system consisting of only the three external conductors (without
a neutral conductor). The N-lug (terminal 0) is not connected. Only
the phase-to-phase voltages are indicated in the display.
Single-phase network
The electrical system (generator, busbar, and mains) is a
wye system consisting of the three external conductors and a neutral
conductor. As a result, the N-lug (terminal 0) must be connected. The
phase-to-phase voltages and the phase-to-neutral voltages are indi-
cated in the display.
CAUTION
If the following parameter is configured to "singlephase" a phase/vector jump monitoring is not possi-
ble.
Parameter
24
Voltage meas.
Mains ----------
This screen affects
the protective functions.
Voltage measurement system protection
threephase / singlephase
The device can either monitor the phase-to-neutral voltages (four-wire system) or
the phase-to-phase voltages (three-wire system). Generally the phase-to-neutral
voltages are monitored when using the 400V model on low-voltage systems, and
the phase-to-phase voltages are monitored when using the 100V model for the me-
dium-high-voltage systems. Monitoring the phase-to-phase voltage is vital to pre-
vent detection of line-to-earth-faults in compensated or isolated mains applications,
which result in a voltage monitoring system fault.
singlephase
.. The voltage at the terminals 1 through 4 are measured as a four-wire
installation. All subsequent screens concerning protective functions
refer to the phase-to-neutral voltage (V
L-N
).
threephase
... The voltages at the terminals 1 through 4 are measured as a three-
wire system. All subsequent screens concerning protective functions
refer to the phase-to-phase voltage (V
L-L
).
