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6.4 Changing the Power Calculation Circuit Clock Frequency
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U input
I input
Multiplier Smoothing circuit P
Instantaneous power
2.37 kHz 2.44 kHz 2.604 kHz
NOTE
6.4 Changing the Power Calculation Circuit Clock
Frequency
Power measurement is carried out by direct input of the voltage and current
waveforms to a multiplier, where an instantaneous power waveform is
created. This is then passed through a smoothing circuit.
To eliminate the multiplier offset, this unit is designed to allow stable
measurement of input voltages and currents chopped at a frequency of 2.44
kHz.
However, if the input waveform includes a component with a frequency
which is an integral multiple of 2.44 kHz, the indicated power value may
fluctuate periodically. In this case, use the following procedure to change the
frequency (the clock frequency of the power measurement circuit).
1. Turn the power on.
2. Press the
SHIFT
→
ENTER
keys during self testing.
3. After self testing, the current frequency is displayed.
4. By pressing the ▼ or▲ keys change the frequency.
5. Press the
ENTER
key to enter the setting and the normal measurement mode
is returned.
6. Press the
ENTER
key again or
EXIT
key, the normal display is returned.
･ This setting is saved in backup memory. It is not changed, even by a system
reset.
･ If a backup error occurs, this is reset to 2.44 kHz. This is also the factory
default setting.
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