Omicron CPC 100, Reference Manual

Page: 133 / 382

Current Transformer
4 - 43
CT Low Power (Ratio)
Use the CTLowPower test card to measure the ratio of a low power current
transformer.
A low power current transformer contains a built-in burden, and provides an
output voltage that is directly proportional to the primary current. For both
protection and measurement only one transformer is required. A low power
current transformer provides a wide nominal current range, and operates linear
and without saturation through the entire range up to the short-circuit current.
To carry out this test, disconnect the ODU plug of the current transformer’s
secondary side from the protection relay, plug it into
CPC 100 V2AC input, and
inject current up to 800 A from CPC 100 800A AC output or up to 2000 A using
the CP CB2 current booster connected to the " EXT. BOOSTER " output to the
current transformer’s primary side.
Figure 24:
Setup for a CT ratio low
power test
Please refer to the note below.
electronic
protection
relay with
low
voltage
input (e.g.
22.5mV at
Inom)
built-in burden
shielded cable with
twisted wires