Current Transformer Installation
Overview
A current transformer (CT) produces a voltage
output signal directly proportional to the current
flowing in the conductor around which it is
positioned. The output signal from the CT is sent
to the meter and the current flow in the primary
circuit calculated. A CT is required for each phase.
•
Only CT’s listed by the manufacturer should
be used. Under NO CIRCUMSTANCES use any
other type of CT as severe damage or injury
may result.
•
Current transformers are marked with the
ratio between the maximum primary current
and the maximum secondary signal. For
example a 200 A:333 mV CT produces a 333
mV output signal when the maximum rated
200 A is flowing through the primary.
•
It is best to match the CT primary as closely
as possible to the maximum expected
current to get the best accuracy. This is
because CT’s are less accurate at low loads
than they are at full load.
•
If using a 200 A CT you will need to input a
figure of 200 into the Eniscope meter
settings menu. Information on how to
complete this, can be found in the
commissioning section, under meter setup.
C
Electricity Monitoring
ii CT Installation
Polarity
•
CT’s are direction sensitive and must
be fitted the correct way around. CT’s are
marked with an arrow on the body to
indicate which direction they should face
around the cable or buss-bar. The arrow
must point towards the load or in the
direction of normal power flow.
•
The CT outputs must be connected to the
meter the correct way round, otherwise
the meter will not register correctly (i.e.
negative readings). Current transformers
are supplied with secondary leads black
and white in colour which must be
connected to the correct terminals on
RJ12 adaptor.
•
The CT’s must be connected to the correct
phase inputs on the meter. The meter
will not register correctly if the CT for L1
is connected to the inputs for L3 current,
for example.
•
Unused CT inputs should be shorted
together to avoid spurious readings.
Please follow the instructions on the next pages for a successful installation
[ E N S C O P E H Y B R I D M A N U A L ]
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