Type A circuit breaker

[pluged]

Hi can anyone tell me what did the Type A circuit breaker change to is it a type B now?
I have come across a 15 Amp Type A in a consumer unit.

What is the Zs of it please?

 

[Darkwood]

Because the prefix A is also very common to another symbol on the mcb and means something else...

Seek manufacturers details for Zs requirements.

 

[Richard Burns]

From the Beama guide to circuit breakers

Trip Type	Range of Trip (In)	Load Type	Application Load
BS EN 60898 Range
B	3 to 5 I[SUB]n[/SUB]	Resistive	Domestic, Heaters, Showers, Cookers, general socket outlets
C	5 to 10 I[SUB]n[/SUB]	Inductive	Motors, general lighting circuits, power supplies.
D	10 to 20 I[SUB]n[/SUB]	High Inductive	Transformers, motors, discharge lighting circuits, computers.
BS3871 Range (Old)
	2.7 to 4 I[SUB]n[/SUB]	Resistive	Domestic, Heaters, Showers, Cookers, general socket outlets
2	4 to 7 I[SUB]n[/SUB]	Resistive/Inductive	Small inductive switching loads, lighting and domestic circuits
3	7 to 10 I[SUB] n[/SUB]	Inductive	Motors, general lighting circuits, power supplies.
4	10 to 50 I[SUB] n[/SUB]	High Inductive	Transformers, motors, discharge lighting circuits, computers

There is no A type instantaneous tripping characteristic to avoid confusion with the abbreviation A for amperes

 

[Darkwood]

There did use to be Richard I've seen them myself...

 

[GB.Kayak]

There did use to be Richard I've seen them myself...

Happy to be further corrected, d ...

An interesting conundrum then ... Richard appears to be quoting the industry trade body, BEAMA, from the document linked here: http://www.beama.org.uk/download.cfm/docid/6bca1329-8a17-4c89-b86a629f18d74bb8. It summarises the development of standards for MCBs from BS 3871 and IEC 898 to BS EN 60898. I admit I was not around when the first standard was published and in university when the last was and have come late to the subject. I also know that sometimes things are tried, perhaps Type 'A' MCBs ... and are rapidly dropped for some 'survival of the fittest' reasons. I am surprised that they are not mentioned in the linked documents; moreover, the document specifically mentions why the nomenclature chosen excluded 'A'.

 

[Richard Burns]

Possibly before 1965 i.e before BS3871, also the disclaimer for A is on the BS60898 table (though why a 1-4 curve may be renamed as A I am nto sure).

Of course you can get RCDs of an A type (or AC or B) which is entirely different.

Then again there are other curves as well, too many for me to remember, S J K all ring bells, possibly M as well.

 

[Knobhead]

There did use to be Richard I've seen them myself...

I've fitted them.

OK they're old.

 

[pluged]

I do know that they changed the A type so it does not get mixed up with Amps (A)

Do you know what they are named name and what the Zs is please?

 

[GB.Kayak]

Possibly before 1965 i.e before BS3871, also the disclaimer for A is on the BS60898 table (though why a 1-4 curve may be renamed as A I am nto sure).

Of course you can get RCDs of an A type (or AC or B) which is entirely different.

Then again there are other curves as well, too many for me to remember, S J K all ring bells, possibly M as well.

I've fitted them.

OK they're old.

I do know that they changed the A type so it does not get mixed up with Amps (A)

Do you know what they are named name and what the Zs is please?

The issue here ... and I was too dull to point it out when I first came across the thread is that once again there is insufficient information to be able to answer the OP. I am making another assumption here, based on the document that I linked to earlier and the subsequent posts that 'A type' fuses existed ... but not within the standards that were summarised in the linked document.

pluged, what is the British or other standard to which the device that you are referring to was made? Clearly it seems unlikely that you are referring to either MCBs to BS 3871 or BS EN 60898.

 

[Pete999]

From the STROMA data sheet 15 A type A BS 3871 cb Max ZS 1.05 Ohms

 

[pluged]

From the STROMA data sheet 15 A type A BS 3871 cb Max ZS 1.05 Ohms

Thank you

 

[Pete999]

Thank you

youre welcome, pluged, plug the thanks button

 

[GB.Kayak]

From the STROMA data sheet 15 A type A BS 3871 cb Max ZS 1.05 Ohms

P, I started a thread on the subject of BS 3871 MCB time - current performance earlier in the year; following the first principles described in spark 68's post on the page linked here http://www.electriciansforums.co.uk...871-time-current-characteristics-again-2.html gives a very different result for the Zs for a 15 A type 1 MCB to BS 3871.

Zs = 0.8 x (U0 / (4 x In)) = 0.8 x (230 / (4 x 15)) = 3.07 Ω

The 4 in the (4 x In) comes from the table that Richard Burns posted, for a type 1 MCB to BS 3871, for those that do not know!

or to BS 7671 Amd 3

Zs = 3.07 x 0.95 = 2.91 Ω

I do not have a copy of BS 3871 and am therefore unable to state with absolute certainty that type A MCBs do not exist within the standard. Please would someone with a copy of BS 3871 prove incontrovertibly the existence or otherwise of type A MCBs within this standard. I am always happy to eat humble pie and expand my own knowledge but I side with 'doubting Thomas' when it comes to believing what others say!

 

[Darkwood]

They are that old GB.Kayak that you would probably have to get an old version of the BS standards to find them listed, they were discontinued decades ago.... I found one in a machine control about 15yrs ago and couldn't believe what I was seeing ..even thought it might be a manufactures printing error until I was told they existed for a very brief period.

 

[GB.Kayak]

They are that old GB.Kayak that you would probably have to get an old version of the BS standards to find them listed, they were discontinued decades ago.... I found one in a machine control about 15yrs ago and couldn't believe what I was seeing ..even thought it might be a manufactures printing error until I was told they existed for a very brief period.

So are you saying that we are talking about a Type A MCB to BS 3871? Or is it another BS?