38
Sub Meters
GE Multilin
5.4.1. CT Connections
Mount the current transformers (CTs) as close as possible to the meter for best accuracy. The
following table illustrates the maximum recommended distances for various CT sizes,
assuming the connection is via 16 AWG cable.
Table 5-1: CT Size and Maximum Distance
5A CT Size
Maximum Distance
(CT to Meter)
2.5 VA
10 Feet
5.0 VA
15 Feet
7.5 VA
30 Feet
10.0 VA
40 Feet
15.0 VA
60 Feet
30.0 VA
120 Feet
Field Programmable CT Primary range : 1A to
99k
A AC RMS.
CT Secondary
: 1A or 5A AC RMS (programmable)
Other values are also programmable to compensate CT errors if desired.
EPM 2000 CT burden
: 0.2 VA max. per input.
See the
Setup (Field Programming) section
for programming details.
IMPORTANT: The CT Primary and Secondary values must be User Programmed
before using the Meter. Otherwise, the readings will be wrong.
NOTE 1: With Dual - Range CTs, select the best range for programming the EPM 2000. Do
not change the range thereafter without re-programming the EPM 2000; the EPM 2000 will
read erroneous values.
5.4.2. CT Polarity
When the meter is connected using the CTs, you must maintain the correct CT polarities. CT
polarities are dependent upon correct connections of CT leads, and upon the direction the CTs
are facing when clamped around conductors. The dot on the CT must face the line side; the
corresponding secondary connection must connect to the appropriate input on the meter.
Failure to connect CTs properly results in inaccurate power readings. If your meter is not
reading power properly, it is more than likely the CT is incorrectly wired. If one or two CTs
are reversed, then Energy parameters accumulate only one phase value. If two or all the
phases of the CT are reversed, Energy will not accumulate. (Note that EPM 2000 does not
have the export energy option).
CAUTION
:
Before wiring, de-energize the CT secondary by shorting
it via a shorting block.
Under no circumstances must the CT secondary be left open-circuited,
even momentarily, when primary current is flowing. This causes high
voltages that will overheat and explode the secondary of the CT and
damage the instruments as well.