MCCB

[frm2005]

Hi Just need a answer to this, is there a minimum amount of fault current needed to open a 25ka 63amp MCCB? On test we have a 2ka pssc.

 

[steptoe]

your specs arent very clear,

generally if its rated at say, 25kA that means it can withstand a 25kA fault without being unusable

whats is the actual rating of it?

what is the 63A ? the rating of it? then thats the current its rated at,

need a proper spec of what it actually is tbh

it cant be a 63A and a 25kA

unless you mean its PFC is 25kA

and its operational rating is 63A

 

[Blue Duck]

unless you mean its PFC is 25kA

and its operational rating is 63A

This makes sense, nothing else does...

h34r:

 

[steptoe]

This makes sense, nothing else does...

h34r:

I have a job for you,,,,,,     ]   h34r: :Sorry: :wub:

 

[Blue Duck]

Does it involve stripping pyro with an angry goose?

Or another type of job?

PM?

 

[frm2005]

Rated at 63Amp operating current 

25ka pfc as mentioned.

I want to know if this will open safely under falut? 

The consultant is adherent that we use MCCBs to protect the flats as opposed to mcbs as we have designed it.

We will have a maximum of 2ka pssc within the flats, would the mccb safely open if the submains were to develop a fault? 

 

[Andy™]

generally if its rated at say, 25kA that means it can withstand a 25kA fault without being unusable

its capable of breaking 25ka but at that fault current it may not survive

 

[Lurch]

I want to know if this will open safely under falut? 

I don't think you fully understand how to design a circuit. Your question is still vague and confusing, mainly stemming from your inability to understand how an protective device works, which is worrying.

 

[Andy™]

Rated at 63Amp operating current 

25ka pfc as mentioned.

I want to know if this will open safely under falut? 

The consultant is adherent that we use MCCBs to protect the flats as opposed to mcbs as we have designed it.

We will have a maximum of 2ka pssc within the flats, would the mccb safely open if the submains were to develop a fault? 

well id suggest that a 63A MCCB will take a bit over 63a to operate (in exactly the same way as an MCB would), and since 2ka is well below its max of 25ka...

maybe go back to college?

 

[frm2005]

Are you taking the piss? 

I know how the device works 

I have run my own electrical company for 15 years.

The fault current noted on the device is what the device can safely cut agreed I have no issues with that.

My worry is that with a low falut current of less than 1ka in some instances would the mccb open.

 

[Andy™]

am i taking the piss? from a 'electrician' who's run his own business for 15 years asking what current will be needed to trip a 63a MCCB?

have you tried the obvious of the time / current charts?

 

[frm2005]

well id suggest that a 63A MCCB will take a bit over 63a to operate (in exactly the same way as an MCB would), and since 2ka is well below its max of 25ka...

maybe go back and Read what I'm trying to say who the courgette are you to tell me to go back to college. 63amp is for overload. Our discrimination calcs show us that the devices we have chosen will operate as they should.

We have a 800amp incomer feeding individual blocks of flats, with in these blocks are additional lv panels feeding MCB boards Which feed the boards within the flats. I know what I'm doing you floppy cock. 

My question is the consultant wants us to change the MCB dis boards to MCCB distribution boards which is wrong in my opinion.

 

[Andy™]

fault current is also based on 63a you idiot. must have skipped day 5...

 

[frm2005]

Yes I did I was ******** you mum, thanks for *.*.*.* all 

 

[Andy™]

best you can come up with? you need to try a bit harder

 

[steptoe]

its capable of breaking 25ka but at that fault current it may not survive

School day, as they say,

I always thought that was the current it 'could' survive

 

[frm2005]

best you can come up with? you need to try a bit harder

It's been a long day, The consultants worry is the high falut current quoted be the DNO, however this isn't an issue further upstream 

 

[steptoe]

It's been a long day, The consultants worry is the high falut current quoted be the DNO, however this isn't an issue further upstream 

2kA   ,,,???????

:slap

thats hardly a high fault current.!!!!!!

 

[Andy™]

tell the 'consultant' that if he wants to put his name to the design of the installation then you will fit what he wants

of course a 2ka fault current is nothing special. about the only thing not capable of that is a 3036

 

[frm2005]

2kA   ,,,???????

:slap

thats hardly a high fault current.!!!!!!

the DNO has quoted 25ka, we get 2ka further upstream