Varistor/MOV for UT61e

[nabardwell]

Also i apologize for misspeaking I meant the CE mark not the UL certification.  Both UL and GS require independent verification by a certified test facility CE does not.

[nabardwell]

Here is the newest German 61e with input protection the layout is exactly the same as the 61e that i have but with movs.  The place i found it is a German form i asked them to take more pictures of the movs and ptcs so we can see the values.
http://www.mikrocontroller.net/topic/358485

[joeqsmith]

Would be fun to see if it fairs any better than the other flavors of UT61Es out their.  The 181A is certified but dies with very little effort.   I guess it dies safely so it's ok.   

Does the GS mark require any sort of EMC testing?

[joeqsmith]

 

If your question was directed @ me (I see Mosher answered it from his perspective) ....

Only in that I agree with your post.  Rest was for OP.

[MosherIV]

I stand corrected. I was not aware that the European version had been certified. Cool 

Worth putting the MOVs in then 
(Yes, I know it does not make the Chinese model GS certified but does improve the input protection, at very least from static)

[ProBang2]

[...]
Does the GS mark require any sort of EMC testing?

The UT61e is certified to the standard of 2006 (valid at the time of the certification), so it has to survive ESD up to 4 kV.
The standard has changed IIRC in 2014 (valid from 2015) to ESD up to 8 kV, but that is not important for the UT61E.

[joeqsmith]

[...]
Does the GS mark require any sort of EMC testing?

The UT61e is certified to the standard of 2006 (valid at the time of the certification), so it has to survive ESD up to 4 kV.
The standard has changed IIRC in 2014 (valid from 2015) to ESD up to 8 kV, but that is not important for the UT61E.

So I looked up what I could find out on the GS mark.  Over and over they talk about it being a safety mark.   I found a document that shows how they refer to the IEC standards.   In the case of multimeters, looks like they follow 61010.  Imagine that.    What I did not find was any reference to 61326.    Can you point me some sort of reference that shows how the GS mark is calling out the ESD testing?   

I would like to have a 61E GS to repeat the tests on.  Wonder if it really would fair any better.   Maybe one of the GS owners would be willing to risk their meter with the same grill starter I use.   

https://www.amazon.com/MHP-Piezo-Push-Button-Ignitor/dp/B00VN1JBSW/ref=sr_1_8?ie=UTF8&qid=1468549797&sr=8-8&keywords=grill+ignitor+piezo

[ProBang2]

[...]
What I did not find was any reference to 61326.
[...]

Reference: http://www.certipedia.com/certificates/50172953?locale=en&page_number=1

[joeqsmith]

[...]
What I did not find was any reference to 61326.
[...]

Reference: http://www.certipedia.com/certificates/50172953?locale=en&page_number=1

Thank you very much for finding this.   I would really like to run one of these.   It would be funny if the grill starter still took it out.  I'll look into it.

[MosherIV]

Hi

I finaly got round to ordering and installing the MOVs.
See attached pictures.

I went with these in the end
http://cpc.farnell.com/epcos/b72210s0381k101/varistor-40-0j-385vac/dp/RE03689
These turn in at 505V DC
385V AC
and clamp at 1025V

Meaning that the input protection kicks in at 1010V DC and 770V AC.
I have no proof od this, and I do not have the equipment to test this.

I did a check on the capacitance measurement before and after and yes the MOVs do affect the capacitance measurement. It adds around 300nF to the measurement but if the delta (or relaitve) mode is used this removes the stray capacitance.

[joeqsmith]

Looks good.

I took another look at the layout of the 61E I just bought, what people have done and the GS marked meter.   Would really like to know what was used in the GS marked meters.   

What's your plan now?

[SeanB]

Thereare lower capacitance MOV's which will do the same job, albeit with lower power handling ability, but those used will work well enough.

Joe, you might want to buy a pack of them and add to any meter that has the pads, and compare to another identical meter without them. Should at least survive the test a few times.

[MosherIV]

  What's your plan now?

Erm...........
Just use the meter 

I do not have access to any test gear to check the input protection.

If I have access to PSU that can reach 1000v then I will try the meter on it.

[joeqsmith]

I already know where this particular rev of the board fails from the factory.  It's pretty much like many of the UNI-T's.  Was really hoping everyone who recommend a change would have had some data to back it up. 

I would guess that the GS meter would do better.  At least survive long enough to get to the transient generator anyway.     

Let me look into it a bit and see what I can come up with.   You can bet after I mod it, I will go ahead and test it so at lease we can see if there was any sort of gain.  The PCB layout is better and I don't think I will need to chop it up like the 181A.   

[joeqsmith]

Mosher, did you look to see if there was an adjustment for capacitance?   Actually, it may help to have some sort of full alignment procedure for it. 

[MosherIV]

Mosher, did you look to see if there was an adjustment for capacitance?   Actually, it may help to have some sort of full alignment procedure for it.

I believe there is but I am not planning on adjusting it.

Using the 'Rel' or Delta mode seems to remove the added capacitance.

[joeqsmith]

Did find a schematic for an older version of the meter.  Still may be helpful.  Most trimmers appear to be marked on the board so shouldn't be too much of a problem. 

[MosherIV]

Hi

Yeah got that schematic. I think I will leave my meter as is now.
I have a Fluke 187 on the way, new toy to play with

I might have a go at building a voltage multiplier to reach 1KV in the future.

Thanks.