Panasonic KW8M - Page 17

KW8M Eco-POWER METER
8
◆How to attach the Current Transformer (CT)
・One current transformer (CT) is needed to measure 1P2W system. Two CTs are needed to measure a
1P3W/3P3W system. Three CTs are needed to measure a 3P4W system. Using all CT should be the
same.
・Check beforehand that the thickness of the electric wire is smaller than the through-hole of the CT.
・When connecting CT, connect the secondary side to the terminal of the main unit first, and after that
wire the primary side to a load electric wire.
Incorrect order might cause an electric shock or break CT.
・The CT has polarity. Wire correctly according to the K and L marks.
Wrong direction can’t measure correctly.
・When closing clamp-on type CT, check that there is no foreign materials on the divided face. And
make sure it is closed securely once the wire is in place; if not the measurement value will be not
accurate.
・When CT’s cable is extended, it is possible to extend up to about 10m with the cable of AWG#22 or
more cross section under the environment without noise at all. Please use the thick cable as much as
possible. *Please check beforehand with the actual system in case of extending the cable.
･If there is some distortion by harmonic or waveform, it may not measure correctly. Please check with
the actual system before adopting it.
・Separate the wiring (strong electric part) of the measured voltage input terminal (operating power
supply terminal) from the CT cable. It may not satisfy the accuracy due to noise.
◇To connect CT with secondary current 5A
How to connect the unit to measure by combination with existing commercial CT
(1) Select 5A at CT type setting mode (CT-T).
(2) Set the primary current of measured commercial CT (secondary current 5A) at primary side
current of CT setting mode (CT-1).
< ex > If the measured CT is 400A/5A, set to”400”.
(3) Clamp the dedicated CT for 5A (AKW4801), which is connected to the main unit first, to
secondary side of the commercial CT. CT direction (K→L) should be set for the commercial CT
direction.
(Connection example)
With Ammeter etc.
Secondary current
Breaker
Dedicated CT for 5A
Ammeter etc.
Power supply
CT with 2nd current 5A
L K
K
L
Eco-POWER
METER
Load