P54x/EN MR/La4 Measurements and Recording
(MR) 8-12
MiCOM P543, P544, P545 & P546
MR
1.4.5 Rms. voltages and currents
Rms. phase voltage and current values are calculated by the relay using the sum of the
samples squared over a cycle of sampled data.
1.4.6 Demand values
The relay p
roduces fixed, rolling and peak demand values, using the reset demand menu
cell it is possible to reset these quantities via the user interface or the remote
communications.
Fixed demand values
The fixed demand value is the average value of a quantity over the specified interval; values
are produced for each phase current and for three phase real and reactive power. The fixed
demand values displayed by the relay are those for the previous interval, the values are
updated at the end of the fixed demand period.
Rolling demand values
The rolling demand values are similar to the fixed demand values, the difference being that a
sliding window is used. The rolling demand window consists of a number of smaller
sub-periods. The resolution of the sliding window is the sub-period length, with the displayed
values being updated at the end of each of the sub-periods.
Peak demand values
Peak demand values are produced for each phase current and the real and reactive power
quantities. These display the maximum value of the measured quantity since the last reset
of the demand values.
1.4.7 Settings
The foll
owing settings under the heading measurement set-up can be used to configure the
relay measurement function.
Menu text Default settings Available settings
MEASUREMENT SETUP
Default Display Description
Description/Plant Reference/
Frequency/Access Level/3Ph + N
Current/3Ph Voltage/Power/Date
and Time
This setting can be used to select the default display from a range of options, note that it is
also possible to view the other default displays whilst at the default level using the and
keys. However once the 15 minute timeout elapses the default display will revert to that
selected by this setting.
Local Values Primary Primary/Secondary
This setting controls whether measured values via the front panel user interface and the
front courier port are displayed as primary or secondary quantities.
Remote Values Primary Primary/Secondary
This setting controls whether measured values via the rear communication port are
displayed as primary or secondary quantities.
Measurement Ref. VA
VA/VB/VC/A/B/C
Using this setting the phase reference for all angular measurements by the relay can be
selected. This reference is for Measurements 1. Measurements 3 uses always IA local as
a reference.
Measurement Mode 0 0 to 3 step 1
This setting is used to control the signing of the real and reactive power quantities; the
signing convention used is defined in section 1.4.4.
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