DEMA CPM 310 G, User Manual

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RMS Current and Frequency Measurements Menu
RMS Current Measurements Menu measures
amplitudes of current waves of frequencies from 50 Hz
/ 60 Hz (1st order harmonic) to 500 Hz / 600 Hz (10th
order harmonic) to evaluate the root mean square
value of the line primary current and displays the
momentary and peak results. The menu contains:
• R, S, T line and N RMS current values, and
 Momentary network frequency value.
The values displayed on the menu are the network
primary values.
As DEMA CPM 310 G evaluates the primary current
values by utilizing the information acquired from the
secondary signals and the CT Settings menu, the
values at the
CT Settings
menu must be set correctly to
make sure
RMS Current Measurements Menu
displays
correct evaluations.
RMS current values are measured and displayed within
the range of (0.1-40.0) I
n
and (0.1-40.0) I
en
. Values
lower than the base limit will neither be measured nor
be displayed, while values exceeding the upper limit
will be evaluated and displayed as 40 I
n
or 40 I
en
.
If the S1 (BIGDISP) button is pressed on the menu, the
ampermeter interface (shown at the bottom picture) is
displayed. This ampermeter shows all the current
values in the largest visual format possible, to make it
easier for the operator to observe the current readings.
Pressing any other button than the Reset button will
lead the screen to the RMS Current Measurements
menu.
Below the I
r
, I
s
, I
t
and I
n
values, the momentary
frequency measurement is displayed. Note that this
measurement will not be able to be done if no current
can be measured from the CTs (e.g. when the circuit breaker is in open position) and the
f
value will
be displayed as “XX.XX”, as on the top picture.
WARNING!
To ensure the correct operation and measurements of DEMA CPM 310 G relays, the Frequency
parameter at the
System Settings
Menu has to be set correctly! Inappropriate settings may cause in
protection faults and incorrect measurements!
The
Frequency
parameter in the
System Settings
Menu is set to 50 Hz by default. If the network
nominal power frequency is 50 Hz, no changes are needed to be done on the control; however, if the
network nominal power frequency is 60 Hz, the following address is to be followed to set the
parameter correctly to ensure safe and expected functionality of the unit:
Main Screen » Menu » System Settings » Frequency » 60 Hz □
Main Screen » Menu »
Measurements » RMS Current
Digital Ampermetre