Manual 37143A
MFR 15 - Protection Relay & Control
Page 62/119
© Woodward
Type of Monitoring
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NOTE
The following screen will not be displayed, if the parameter "
Volt.-Measuring
" is configured to
"
Phase to phase
" power measurement. (refer to Voltage Measurement on page 43).
Volt. Monitoring
----------------
Monitoring for
Phase-neutral/Phase to phase
The unit can either monitor the phase-neutral voltages (four-wire system) or the
phase-phase voltages (three-wire system). Usually, for low-voltage system (400 V
version) the phase-neutral voltages are monitored, while for the medium and high-
voltage systems (100 V-version), the phase-phase voltages are monitored. The
monitoring of the phase-phase voltages is recommended to avoid a phase-earth
fault in a compensated or isolated mains resulting in the voltage protection tripping.
The only effect on the screen "Voltage measuring" is the one described in the
above note. The settings in the screen "
Volt.-Monitoring
" do have the fol-
lowing effects on the configuration screens:
Phase-neutral:
The voltage at the terminals 1/2/3/4 is measured as a four-wire in-
stallation. All subsequent screens concerning voltage measuring refer
to phase-neutral voltage (V
Ph-N
). This is indicated in the configuration
screens by the supplement [
Phase-N
].
Phase to phase:
If the voltage system connected to the terminals 1/2/3/4 is a three-
wire system, this setting must be selected. All subsequent screens
concerning voltage measuring refer to phase-phase voltage (V
Ph-Ph
).
In the configuration screens, this is indicated by the supplement
[
V(ph-ph)
].