Yokogawa WT1600 Digital Power Meter

[_Wim_]

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.

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]

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.

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]

...

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.

[www.MKRD.info]

My Purchase Order Request was approved, my purchasing guy should be buying this soon.
Is Instapak secure enough to travel all the way to USA? Can we pack it even "better"?
I am still curious, though, what did the limited-cal sticker say? Was it related to the module/element or to the chassis? I am buying this to pull and use the module, the chassis with only three bays is of almost no use for me right now.
And there was some flux from previous(?) repair on the module, was this cleaned up a bit as part of repair?

[Ice-Tea]

Let's see if we can wake the Captain for some of these questions. Re. packaging. Not sure if there's something better beyond Instapak. Here's a video:



Also: you or your puchasing department can also contact me directly (PM) in case you're not hellbent on lining eBays pockets even more. Use eBay if you like that extra level of protection/leverage but if you have some level of confidence in me, you can save a few $.

[capt bullshot]

My Purchase Order Request was approved, my purchasing guy should be buying this soon.
Is Instapak secure enough to travel all the way to USA? Can we pack it even "better"?
I am still curious, though, what did the limited-cal sticker say? Was it related to the module/element or to the chassis? I am buying this to pull and use the module, the chassis with only three bays is of almost no use for me right now.
And there was some flux from previous(?) repair on the module, was this cleaned up a bit as part of repair?

Regarding the packaging, I doubt it can be done better - that Instapak stuff does a nice fit around the sides of the unit, and there's some other stuff used to fill up the spaces that the Instapak didn't reach. Of course, everything can be done better - but I don't think it's necessary here.

There's a cal sticker on the plugin and one at the front side of the instrument. Can't remember what they said, the unit is packed and I couldn't find photos of these stickers.

There's some flux residue at two through hole components, looks like the common residue from handsoldering. Most probably left from a previous repair, I didn't replace or de-solder any components. IMO and from my experience nothing to be concerned about. I didn't clean anything - following the "if it isn't broken, don't try to fix it" principle. Basically the electronics is fine, just the cal coefficients of the current channel were way off. Maybe left from some attempt to adjust it without proper knowledge of how to do this. I've digitally adjusted the current ranges to my best effort, but that's no calibration in the correct meaning of calibration. I left the voltage ranges untouched.

[www.MKRD.info]

Thanks for the info!
We have a contracted on-site calibration service company, this unit will go thru a calibration anyways as soon as it is received, onsite for easier items, or mailed out if it cannot be done on-site. The main objective is for the unit (and everything else I get thru eBay these days) to pass calibration.

Have you dealt with Yokogawa Power Analyzers generally before?
It is weird that this only has a three-bay back cover installed. I wonder if expanding to six bays was just a matter of a back panel or if some electronic tweaks are also required.

Also, the general mode of failure of these 5A elements is people passing too much current thru the elements and frying shunt resistor. Do you have experience repairing shunt resistors on these modules?

It is moronic that Yokogawa is not at all interested in any support or repairs of these units. Even a WT1800 I have, even though it is still being sold "my unit's serial number is too old". What a load of horsecrap!!!

[coppice]

It is moronic that Yokogawa is not at all interested in any support or repairs of these units. Even a WT1800 I have, even though it is still being sold "my unit's serial number is too old". What a load of horsecrap!!!

I've never found what Yokogawa support is like, as I've never had one of their power meters/analysers go wrong. I've used some pretty old ones, too.

[capt bullshot]

Have you dealt with Yokogawa Power Analyzers generally before?
It is weird that this only has a three-bay back cover installed. I wonder if expanding to six bays was just a matter of a back panel or if some electronic tweaks are also required.

This has been the first Yokogawa Power Analyzer on my bench, I've seen various others before. Some 20 years ago, my job was developing "Power Quality Analyzers" which include most of the power analyzing functions the WT1600 has and a lot more PQ specific stuff, but specialized on power line frequency usage. So they had lower bandwidth (in the 5 ... 50 kHz ballpark).
I can't remember, the unit is already packed and I couldn't find photos that showed the backplane. So I can't tell whether the  connectors for ch 4..6 were fitted or not. In general, I would expect the chassis to be able to work with up to 6 channels, and this particular unit might have been a 3ch unit somewhen in the past - but that's just guessing. As you most probably already know, one can easily swap the input modules, the software maybe complains once because of the modified configuration and forces a factory reset, but otherwise this just works with any number and any combination of modules.

Edit: Looking at the photos within this thread, I'd say the back panel can take up to 4 modules, and the backplane should have all connectors for up to 6 channels fitted.

Also, the general mode of failure of these 5A elements is people passing too much current thru the elements and frying shunt resistor. Do you have experience repairing shunt resistors on these modules?

The shunt is a 100mOhm one, that of course can be easily fried by overcurrent. The input amplifier circuitry apparently is protected against overvoltages due to overload or shunt failing open, if there's enough overvoltage due to a failed open shunt, I'd suggest to check the protection circuitry, especially the 51R series resistor - as shown in one of my schematic sketches before. I've seen some components fitted at the sense side of the shunt, most probably for frequency compensation purposes. One would have to check if these are specific to the particular shunt and must be "re-adjusted" if the shunt is replaced. Otherwise, I'd expect some issues sourcing a replacement and actual replacement since they've used some small PCBs at both sides of the shunt that would have to be removed from the old and fitted to the new one, or some bodging involved in case you cannot source a mechanically identical shunt.
No, haven't done this before, as I prefer not to fry my instruments