3-24
IM CW240E
3.7
Performing Measurements
with Greater Precision
• After turning the power switch on, let the CW240 warm up (for more than 30
minutes) before starting to perform measurements.
• To perform measurements with higher precision, use the CW240 under the
following environment conditions:
Ambient temperature: 23 ± 5°C
Ambient humidity: 35 to 75% R.H (no condensation)
If the CW240 is installed in a location where the ambient humidity is less than
30%, use an antistatic mat, etc. to prevent electrostatic discharge.
If you move the CW240 from a location of low temperature and humidity to a
location of high temperature and humidity or, if there is an abrupt change in
the ambient temperature, condensation may occur in the CW240. If this
happens, let the CW240 stand still for at least an hour to allow it to adapt to
the new ambient temperature and for any condensation to dissolve. Then
begin operating the CW240.
• Supply the power of sine waves at 50 Hz/60 Hz.
• When using a clamp-on probe, pay attention to the following points:
<1> When performing measurements, hold the clamp-on probe so that the
conductor cable runs through the center of the clamping CT.
<2> Ensure that the orientation of the clamp to the direction of the conductor
cable (from the power supply to the load) is correct, as shown on the right.
<3> Ensure that the clamping CT is properly closed.
Power supply side
(SOURCE)
Conductor cable
Joint section
Clamping CT
Load side
(LOAD)
TIP
The CW240 obtains the measured value from voltage and current inputs.
(For computation equations, see Chapter 17, CW 240 Specifications.)
There may be cases where the CW240 shows a measurement value different from
those obtained by other equipment with different operation principles or computation
equations.