Products > Test Equipment
Yokogawa WT1600 Digital Power Meter
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capt bullshot:

--- Quote from: TERRA Operative on May 17, 2022, 01:59:26 pm ---For service mode, try switching on the instrument while pressing display button. After start up, press shift and then the display button.

https://www.eevblog.com/forum/metrology/yokogawa-wt1600-power-meter-calibration-mode/

--- End quote ---

Thanks a lot!
This works and gives access to the calibration menu. I shall setup up a suitable cal rig tomorrow and report here.
TERRA Operative:
No probs :-+ As mentioned in the TEA thread, I'll send an email directly to Yokogawa Japan and ask for service manuals etc.  :)
capt bullshot:
Good news on well it works now wednesday:

Thanks to the tip by TERRA Operative, I have now access to the calibration menu at the WT1600.
To calibrate (adjust to be correct) the shunt input, one needs a 60Hz current source at various currents from 50mA to 5A. 50mA to 2A (1.99999A indeed) does the Fluke 5100B. For 5A, I went to the basement and fetched this amplifier from a storage shelf, along with the 1mOhm shunt resistor.
Using these, the Tek clamp on CT and two 34401A, I was able transfer the 2A from Fluke to 5A through this amplifier and the 33120A generator. Now the WT1600 shows pretty good results, and nicely agrees with the second Fluke 5101B. This gives at least some confidence into this non-traceable home lab calibration.
I didn't touch the calibration of the voltage and BNC input ranges, since I found them good enough in spec at former tests.


Ice-Tea:
Coming together rather nicely!  8)
capt bullshot:
So, its test it thursday: Update from the "Fun with (Ice-)TEA" dept.

One of the key features of a precision power meter is phase alignment between voltage and current over a wide frequency range.
If you're measuring power at an phase angle near 0°, a small phase deviation between voltage and current will cause large errors in Q (reactive power).
The other way 'round, if you're measuring near 90°, the real power will be near zero while there might be quite large reactive power, and small phase errors will cause large errors in real power (P).

Every half-decent power meter does the real power calculation by multiplying u(t) by i(t) and integrating the result over a multiple of input period time. Calculation of Q might depend on the actual implementation or might not be available at all.

So for my tests, it was the natural choice to conduct the measurements at 90° phase between voltage and current over a large frequency range.

This is the first setup:



The dual channel AFG provides output signals at 90° phase. One channel is fed directly into the voltage path of the instruments. The other is routed through the high speed amplifier and a 50 Ohm load resistor into the current measurement paths. The dummy load resistor provides non-reactive response to a few MHz, it's not that good but good enough for this test.

DUT are the WT1600 and the Clarke-Hess model 2330 power meter.

This is the plot from 10Hz to 800kHz, read out real power of these instruments. Apparent power seen by the meters is about 1.27VA during the tests. Calculating errors is left to those playing along at home as an exercise to the reader, I've attached a text file with the raw values.



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