Author Topic: CAT ratings and interpretation  (Read 20091 times)

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Offline Monkeh

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Re: CAT ratings and interpretation
« Reply #75 on: October 28, 2012, 03:17:55 am »
Is there a date on that document, Dave?

Yes, the latest June 1012 version. 61010-2-033:2012

Dave.
That's interesting! Do we know what the changes were over the last 4 years for instance?

So far as I'm aware, there is no previous version of the document. I certainly don't have access to it if it exists.

There are, however, two other revisions of 61010-1, 1993 and 2001, current revision is 2010. Will supply to Dave if he wants them.
 

Offline Neilm

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Re: CAT ratings and interpretation
« Reply #76 on: October 28, 2012, 03:25:20 am »

Just check to see if it's got a third party testing stamp like TUV et.al on the back. If not then it hasn't been independently tested and certified.
BTW, there is no legal requirement to do this, you can either test it in-house, or just suspect it passes based on design. Anyone can slap a CAT rating on their meter, as there is no body to legally enforce it.
Of course, you need the CAT rating to sell into the EU now, but I believe still no law to say it has to be independently tested.

To place a meter on the market in the EU require that it meet the various directives. For multi-meters, these are the Low Voltage directive, EMC directive. In order to meet the Low voltage directive the meter would have to meet the appropriate international standard.

For the multimeter this is principally IEC61010. It would have to meet all the appropriate parts of 61010, the general requirements, the parts for the measurement circuits and the parts for any accessories that come with it as standard - for example the leads. If the meter came with rechargeable batteries, it would also have to meet IEC62133, assuming that the batteries had a non-acid electrolyte like Ni-mH or Lithium.

I do not believe that there is a requirement to put a CAT rating on the meter if it is not rated for connection to the mains.

However, most meters are so rated and many do not meet these standards. I found a very cheap meter in a market and I took it to work where we have some facilities to do CAT rating tests. I ended picking bits of the meter out of the blast case for a week.


So far as I'm aware, there is no previous version of the document. I certainly don't have access to it if it exists.


IEC61010-2-030 was a new standard. The requirements were originally in the main part one of the 2001 version.

There are a lot of changes from 61010 :2001, it now covers different versions of insulation as well as requirements for tracking on PCBs which was not covered at all in version 2001.

Neil

Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe. - Albert Einstein
 

Offline KedasProbe

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Re: CAT ratings and interpretation
« Reply #77 on: October 30, 2012, 07:58:38 pm »
Reply from Brymen, asking for info related to the updated standard and my BM869 DMM
Nice to see they had the 3rd edition in mind during design. (doesn't mean that it will pass all new test, we will find out later after re-submit)

Quote from: Brymen Product Marketing Manager
BM869 was submitted to UL to safety tests before IEC61010-1 3rd Edition (IEC61010-1:2010 and IEC61010-2-030:2010) was announced formally. UL was testing it only to IEC61010-1 2nd Edition (IEC61010-1:2001). However, BM869 designs had considered IEC61010-1 3rd Edition. It can already meet main safety requirements of IEC61010-1 3rd Edition like the protection to transient or like using the fuses with rating to the highest a.c. and d.c. RATED voltages of any BM869 measuring TERMINALS. Anyway, we will re-submit BM869 to UL to get the tests/checks updated to IEC61010-1 3rd Edition before 2nd Edition DOW (Date of Withdraw).

add-on
Quote from: Brymen Product Marketing Manager
UL probably is the biggest safety test third party in the world. It is always difficult to get product UL Listed, especially UL Listed to toughest CAT IV 1000V. BM869 and our other BM820/BM520/BM867 models should be the only products with complete multimeter functions getting UL Listed to CAT IV 1000V.
« Last Edit: October 30, 2012, 08:29:54 pm by KedasProbe »
Not everything that counts can be measured. Not everything that can be measured counts.
[W. Bruce Cameron]
 

Offline Wytnucls

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Re: CAT ratings and interpretation
« Reply #78 on: October 31, 2012, 03:52:51 am »
From the Brymen reply, it seems that the high voltage rating requirements for fuses is a new one, with IEC61010-2-030:2010. That would explain the existence of so many meters with 250V fuses. It will be interesting to see how long it takes manufacturers to upgrade their DMM models to comply with the latest standards.
 

Offline Lightages

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Re: CAT ratings and interpretation
« Reply #79 on: November 02, 2012, 02:02:41 am »
Actually, from the document I have of the IEC 61010-1 standard dated 2004:

"5.1.5.2 Measuring circuit TERMINALS
Unless a clear indication (see note below) is provided on a measuring instrument that voltage
and current measuring circuit TERMINALS are not intended to be connected to voltages to earth
above 50 V a.c. or 120 V d.c., the TERMINALS shall be marked as follows.
a) Measuring circuit TERMINALS for measurements within measurement category I (see 6.7.4)
shall be marked with the RATED voltage or current as applicable and with symbol 14 of Table
1 (see also 5.4.1 f) and g)).
b) Measuring circuit TERMINALS for measurements within measurement categories II, III and IV
(see 6.7.4) shall be marked with the RATED voltage or current as applicable and the relevant
measurement category. The measurement category markings shall be “CAT II”, “CAT III” or
“CAT IV” as applicable."


AND

"16.2 Multifunction meters and similar equipment
Multifunction meters and similar equipment shall not cause a HAZARD in any possible combination
of RATED input voltages, and settings of function and range controls. Possible HAZARDS include
electric shock, fire, arcing and explosion.
Conformity is checked by the following test.The maximum RATED voltage specified for any function is applied to each pair of TERMINALS in
turn, in every combination of function and range controls. The test source connected to the
equipment measuring TERMINALS during this test is limited to 3.6 kVA for measurement category I
or measurement category II. For measurement category III or measurement category IV, the test
circuit has to be capable of delivering 30 kVA.

During and after the tests, no HAZARD shall arise.
Multifunction meters and similar equipment are to be tested by changing the Function/Range Selector to all
possible settings while connected to the maximum rated source.”
NOTE If test probes are provided with the equipment being tested then they are to be used for the test.
Compliance is checked by testing to verify no hazard occurs when switching selector settings."


So while yes, there is no explicit statement that the fuses must not be rated below the rated voltage of other terminals it is implied. Obviously some or many manufacturers did not interpret  the above correctly or used it as a loophole. It is not a given that a 250V fuse could cause harm in a properly contained housing, but if the fuse is not rated to break the current then other hazards would arise very quickly. I would guess this is why the changes to the latest standard to explicitly  prohibit fuses not rated for the highest voltage on the equipment. But either way, if the terminal itself is not labelled for the safe voltage use on the equipment it has not met the standards since at least 2004.
« Last Edit: November 02, 2012, 02:09:47 am by Lightages »
 

Offline Wytnucls

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Re: CAT ratings and interpretation
« Reply #80 on: November 02, 2012, 03:33:15 am »
This is how I interpret the old regulations:
Assuming the meter passed the destructive 30KVA 1000V test on the A/mA ranges with its 250V fuses and the CAT III/IV tests on the Volt/Ohm ranges, the correct labelling would be CAT IV 600V CAT III 1000V on the Volt/Ohms jacks and 1A/10A MAX, according to fuse ratings, on the A/mA jacks.
I don't see the need to mark the amps jacks with a restrictive voltage if the meter passed the test, not to mention the possible confusion for users, which could lead to voltage measurement with the probes in the amps jacks.
If the meter didn't pass the 30KVA test on the A/mA ranges, it would lose its CAT rating on the Volt/Ohms range or at least be downgraded.
That would make the labelling correct on most meters built before the new regulations came into effect.
« Last Edit: November 02, 2012, 03:35:40 am by Wytnucls »
 

Offline Lightages

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Re: CAT ratings and interpretation
« Reply #81 on: November 02, 2012, 04:12:10 am »
I agree with you. The problem is that there is no requirement for actual 3rd party testing. Therefore, any company could label their meter as meeting a specific CAT rating based on the design only. Perhaps the need to force manufacturers to use fuses rated for the CAT rating stated came from some of these "legally" labelled meters failing in real world conditions and/or tests in a dangerous or harmful way. I would make an educated guess that my UT71E would explode if a 30kVA pulse was passed through the current ranges at 600V. There is no way that little glass fuse is going quench the little plasma fireball that would be created.

The problem with the word is that if there is a way to interpret something in a way that meets a spec or requirement in a way that benefits the manufacturer in cost, many will choose that over following the intent of the specification, instead they try to get around it. I suspect that is why the standard for fuses was changed.
« Last Edit: November 02, 2012, 05:12:49 am by Lightages »
 

Offline Wytnucls

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Re: CAT ratings and interpretation
« Reply #82 on: November 02, 2012, 05:01:44 am »
The datasheet for those fast glass fuses states a breaking capacity of 35A for the 500mA one and 100A for the 10A fuse, both at 250V. I'd love to see how they do at 1000V!
I can't understand why Uni-T went for those weaklings in the 71 series, when cheap ceramic fuses are available in that 205 size and the PCB had a footprint for a 3AG fuse, from the very first board revision. Not HRC, but it would have been a big improvement anyway.
Voltcraft sells the 71 series in Germany under their own brand. I wonder if the fuses were upgraded in that one.
 

Offline Wytnucls

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Re: CAT ratings and interpretation
« Reply #83 on: November 02, 2012, 08:30:02 am »
Here is the certificate of conformity (2009) from Conrad for the UT-71 German brother (Voltcraft VC920):
For those who don't know Conrad, they have the biggest brick and mortar electronic shop network in Germany, selling equipment all over Europe and Eastern Europe as retailers and also online.

The fuses are the same in both versions:
Fuse 1 for protecting the mA range:
0.5 A 250 V fast-acting 5 x 20 mm (F0.5A 250V)
Fuse 2 for protecting the 10A range:
10 A 250 V fast-acting 5 x 20 mm (F10A 250V)
« Last Edit: November 02, 2012, 08:57:09 am by Wytnucls »
 

Offline Lightages

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Re: CAT ratings and interpretation
« Reply #84 on: November 02, 2012, 08:41:04 am »
Wow, Conrad really stuck their neck out on that one. The UT71E does not have any 3rd party testing as far as I can see and the Voltcraft rebadge is being guaranteed by Conrad only!
 

Offline Wytnucls

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Re: CAT ratings and interpretation
« Reply #85 on: November 02, 2012, 09:20:46 am »
Yes, they sure did, but knowing how the German companies operate, they must have done some testing of their own or put the meters through a German safety audit, as litigation would put the reputation of the company at risk.
They also produced their own operating manual for the meters, in several languages.

VOLTCRAFT® products are developed in the “Conrad Technology Centre (CTC).
They have been selling these UT71 clones since 1995.
« Last Edit: November 02, 2012, 09:48:18 am by Wytnucls »
 

Offline T4P

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Re: CAT ratings and interpretation
« Reply #86 on: November 03, 2012, 07:45:30 pm »
Rebadges not clones.
They do the independent testing and probably upgraded the fuses, i remember seeing a UT61X from a german company for slightly more with upgraded fuses
 

Offline Lightages

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Re: CAT ratings and interpretation
« Reply #87 on: January 16, 2013, 06:29:43 am »
Further information from Brymen in relation to a question I sent them on the altitude specification in the manuals:


Altitude up to 2 000 m is the normal environmental condition (clause 1.4.1) in IEC61010-1 safety regulation. Altitude above 2 000 m is specified as extended environmental condition (clause 1.4.2), and all CLEARANCES shall be multiplied by an applicable factor. They are:

 1.14 at 2001 to 3000 m
 1.29 at 3001 to 4000 m
 1.48 at 4001 to 5000 m
 
Per altitude <2000 m, BM869 is a CAT IV 1000V design using clearance of 14 mm, which is, in turn, 1.75 times of 8 mm as in the one step lower CAT III 1000V & CAT IV 600V requirements. It is then a CAT III 1000V & CAT IV 600V design up to 5000 m, the highest altitude as specified in the regulation.

Best Regards,
Gary Wang/Brymen
Product Marketing Manager
 

Offline safetyfirst

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Re: CAT ratings and interpretation
« Reply #88 on: October 08, 2013, 05:50:21 pm »
Here is the timing on the new standards (from http://www.ul.com/global/eng/pages/offerings/industries/healthsciences/ul61010/):

UL 61010 Part 1 - 2nd edition (published 7/12/04) combined the three previous UL standards into a single standard
 - UL 61010A-1 for laboratory equipment
 - UL 61010B-1 for test and measurement equipment
 - UL 61010C-1 for process control equipment into a single standard.

UL 61010-1 2nd edition is completely aligned with the current edition of IEC 61010-1, except for some U.S. national differences. Since the effective date for this standard is January 1, 2014, and all products that only mee the 1st edition must be withdrawn.

There are other dates:

October 1, 2013 -- EU date of cessation for IEC 61010-1 2nd edition.
January 1, 2014 -- UL 61010A-1, UL 61010B-1 and UL 61010C-1 will be withdrawn.
June 1, 2014 -- All new product submissions that are in the scope of IEC61010-2-033 must comply with this standard and UL61010-1 3rd edition
January 1, 2018 -- UL 61010-1 2nd edition will be withdrawn.

We are now in the middle of the transition.  All new submitted products must meet the new requirements.  Previously approved products can continue (until 2018?).  Based on this thread, a safer DMM should meet the 3rd edition requirements
 

Offline Lightages

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Re: CAT ratings and interpretation
« Reply #89 on: October 08, 2013, 05:55:10 pm »
Thanks for the update.
 


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