Products > Test Equipment
Yokogawa WT1600 Digital Power Meter
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_Wim_:

--- Quote from: capt bullshot on May 21, 2022, 11:19:06 am ---Regarding the sampling frequency / bandwidth: There's no trick at all, it just works by the nature of the matter :)

For calculating the basic values (Urms, Irms, P), the signal frequency isn't of concern at all. One just integrates over an integer multiple of the period time, no matter what the actual signal or sampling frequency is.
It's some kind of ETS, though it's not necessary to reconstruct the waveform as the sampling oscilloscopes do.

For example, in the frequency domain, a 300kHz signal gets aliased to 100kHz if a sampling rate of 200kHz is used. For Urms / Irms / real P computation it doesn't matter wether the original signal @300kHz or the aliased signal @100kHz is seen by the calculation, as long as both (U and I) signals undergo the same conversion and keep their phase relationship.
There's one corner case: a signal frequency of an exact integer multiple (including 1) of the sampling frequency gets aliased to DC, this can lead to large errors or at least confusion. Didn't check this with the Yokogawa, but I've seen instruments avoiding this by changing the sampling frequency slightly (afair the Clarke Hess does so).

The WT1600 has a harmonics analysis mode, too. Here's the whole thing a bit different: As you want to apply (usually) a FFT with rectangular window to the input signal, the sampling frequency gets synchronized to the signal frequency by means of a PLL circuit (At least this is my guess from reading the manual). This mode is quite limited in terms of fundamental frequency, maybe max. 1kHz afair. Usually you want to switch an aliasing filter into the signal path to avoid the aliasing here.

--- End quote ---

Thanks for the explanation, that indeed makes perfectly sense. I indeed now see that the harmonics are "limited" to the 25th order of a 1khz fundamental (still plenty I think for actual use).
Ice-Tea:
In case it's not abundantly clear: this unit is for sale. It's been on eBay for a bit:

https://www.ebay.de/itm/144516676626

and at the risk of stating the obvious: PMing here me cuts out eBays stake and makes it a bit cheaper if you wish.

Finally: I'm sure the Capt'n is sick'n tired of having it taking up space, so if you ask nicely I'll probably drop my pa...erh, price some more.
www.MKRD.info:

--- Quote from: Ice-Tea on September 10, 2022, 06:33:13 pm ---In case it's not abundantly clear: this unit is for sale. It's been on eBay for a bit:

https://www.ebay.de/itm/144516676626

and at the risk of stating the obvious: PMing here me cuts out eBays stake and makes it a bit cheaper if you wish.

Finally: I'm sure the Capt'n is sick'n tired of having it taking up space, so if you ask nicely I'll probably drop my pa...erh, price some more.

--- End quote ---

Since it is still for sale on eBay I put in a Purchase Order Request thru my employer to purchase this. It was actually just the one module that I needed (that is, until we blow some more modules).
Are you interested in / capable of repairing modules? I am starting to pile up smoked or degraded (failing calibration limits) modules from PZ4000, WT1600, and WT1800.

If someone else is capable of repairing these modules, contact me, I will keep blown modules till forever.

If the shunt is smoked, is it a reasonable repair job by myself, is part number known, is it easy enough to replace?

US factory thru my local sales rep said NO SUPPORT on these instruments and modules officially.

I also need help identifying part numbers for modules for WT1600 and WT1800. There are only very poor and cryptic markings of any kind, and only on the PCB once cover is removed.
www.MKRD.info:

--- Quote from: capt bullshot on May 21, 2022, 11:19:06 am ---...

--- End quote ---
So what was the statement on the limited cal sticker though, and what was the fix / what repairs were done?
There's a gap from May to Sept, and what's the relationship between capt bullshot and Ice-Tea, from different countries? Confusing... Did this switch hands to from measurements to repair?
Ice-Tea:
- Whether or not the Captain wants to take on repairs I'll leave up to him.
- Have a look at post #17 and following. If I understand correctly, the unit was repaired in the past (prior to me taking it in or the Cap'n having a go at it) but not adjusted. This caused limited cal. The Captain has since adjusted the unit and found it accurate. It's not a traceable adjust or calibration, though.
- The Captain is from Germany and I'm from Belgium but the distance is more like a state away in American terms.
- I send the unit to him for fun and giggless (ie to play around a bit with, compare it with some of his own testgear). I actually wasn't expecing there to be anything wrong with it so the repair was a highly appreciated bonus.
- In order to save a bit on shipping, the unit is still in his lab as it would save the trip from Germany to Belgium.
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