60947 Zs VALUE S

[driverman]

Guys. how do I find the Zs value for a 80A 60947-2 10Ka MCB? At this point in time I don't know the make. Is this a new number for MCB's? Does it make a difference with different manufactures? Cheers

 

[shanky887614]

i looked this up before

here you go

blog.schneider-electric.com/energy-...6/iec-60898-1-iec-60947-2-tale-two-standards/

its a very interesting read and describes the differences

 

[Engineer54]

Silence must mean there is a frantic search for the correct answer. Lol!

I don't have to look up or search. An MCB cannot conform to the requirements of 60947-2, and 60947-2 do not have MCB type standardised tested time/current tripping curves.

I await spark 68's picture with interest!!

 

[shanky887614]

I don't have to look up or search. An MCB cannot conform to the requirements of 60947-2, and 60947-2 do not have MCB type standardised tested time/current tripping curves.

I await spark 68's picture with interest!!

IEC 60898-1 be used instead of IEC 60947-2?

No. Consequences can be dire if residential CBs are used instead of industrial ones. An MCB designed for indoor, pollution-free conditions would be woefully inadequate for harsh, outdoor applications that require pollution degree 3.
Or take the tripping characteristics: IEC 60898-1 clearly describes B, C and D curves with ratio to rated current, while in IEC 60947 2 the instantaneous tripping release may be adjustable according to the need of the user or pre-defined my manufacturer with ±20% tolerance. This is the reason why manufacturers in addition provide a wide scope of different curves: K, Z, MA.
Typically IEC 60898-1 certified CBs meet minimally required performance to proof proper protection of household installations: Pollution degree 2, impulse voltage 4kV, isolation voltage is the same as nominal voltage 400V. That is the reason why usually we meet limited number of printed technical information on CBs.

 

[shanky887614]

in other words there is no such zs value, you need to contact the manufacturer for the information on that breaker

 

[spark 68]

I don't have to look up or search. An MCB cannot conform to the requirements of 60947-2, and 60947-2 do not have MCB type standardised tested time/current tripping curves.

I await spark 68's picture with interest!!

Here you are,

I can zoom in a bit closer if needed.

 

[Engineer54]

It seems i am wrong, ....i've always considered 60947-2 has only relating to MCCB's and the like certainly never considered it covering MCB's, can't say i've ever seen an adjustable MCB before either. Just goes to show what a complete shambles all these different standards are in, and the confusion they ultimately create....

Well i won't be losing any sleep over it!! lol!!

 

[spark 68]

What we really need now is the OP to confirm that he actually meant an MCB and not an MCCB, that one incidentally was pulled because it is cracked around the bottom L terminal, you might be able to see it on the picture.
It is a C curve fixed, and the auxiliary block fits on the side there is a cover to remove.

 

[Engineer54]

Just checked what BEAMA has to say....

Read the last paragraph on page 19, (''Determation of maximum earth loop impedance (Zs'') makes everything as clear as mud!! lol But it is confirming my take on breakers conforming to IEC 60947-2.

 

[driverman]

Thanks for all replies. Bit of an update. It is a MCB but the actual size of it is 1 and half modual size (1.5). When time I'll read all above comments / views with interest.

 

[Tidy Max]

Technically correct E54, they are known as MCCB

The 60947-2 standard is a lot deeper though, it covers low voltage circuit breakers up to and including ACBs, the Beamer Guide just classifies them as "Low Voltage Circuit Breakers"

I don't own the standard, Net Blind Paul is the Standards guru on here.

I have here in my Possession an ABB 16A "MCB" that complies to 60947-2, it is a DPSN type that has a "C curve", it also has provisions for auxiliaries to be fitted.

Ps. will post a picture later on, my phone takes cr*p pictures, I will have to wait for my camera to charge lol

What do you mean by provisions for auxiliaries?

 

[Engineer54]

What do you mean by provisions for auxiliaries?

Provision for additional auxiliaries such as modules via a side operated mechanical connection containing shunt trip, N/O N/C contacts etc, etc, that can be operated by the MCB or trip the MCB.


Check out MCB catalogues from people like ABB, SCHNEIDER etc, and it'll show you the type and number of auxiliaries that can be fitted to their MCB ranges...

 

[driverman]

OK, this is not my thing really, head hurts! Anyway,I've tried getting MI instructions for said MCB. I have now seen one, so to confirm. It is definitely an 80Amp type "C" SP mcb, 1.5 modular wide. 60947-2. Companies that might of made it are; [FONT=&quot]YUEQING VORAX ELECTRIC CO.,LTD. [/FONT]
or even Delixi, Chint and Jinda (Ginda). MCB on a TN earthing system, therefore 5 sec disconnection time required.
MCB has company name on it.......not the manufactures!

 

[spark 68]

Okay then if the curve is fixed then use

230/(In X Type multpier) = A

A X 0.8 = max Zs

And if to amd3 multiply again by Cmin

C type multiplier worst case is X 10

 

[driverman]

Okay then if the curve is fixed then use

230/(In X Type multpier) = A

A X 0.8 = max Zs

And if to amd3 multiply again by Cmin

C type multiplier worst case is X 10

Thanks for your reply. However I'm going to be honest here. I don't understand the formula as such. What is "type multiplier"? Also amd3 / Cmin.

 

[spark 68]

I should point out here that the above formula works for all of the BSEN 60898 type MCBs, try it with lower Ampage common MCBs and you will see it works close enough to the values given in the OSG.

Applying it to fixed MCBs to 60947-2 will err on the side of caution as the manufacturers data will lead to a more accurate figure, and this may be slightly higher than this calc produces due to the way that standard is applied, this calc will still be of use where manufacturers data is not available, but only for fixed types of MCB, it will be of no use for MCCBs or above, and anything that may be adjustable or time delayed etc.