MCCB with RCD settings

[Taylortwocities]

You don’t discriminate RCDs on the mA trip current, you discriminate on the basis of time.
That is what time delay RCDs are for.

 

[Bradley6969]

Out of interest,what did you set the delay,to?

It’s at 1

 

[Bradley6969]

Has anyone set one up before and could tell me? Or know how to

 

[Deleted member 26818]

Has anyone set one up before and could tell me? Or know how to

???

 

[DPG]

It's a wind up this one. Guaranteed

 

[Bradley6969]

It's a wind up this one. Guaranteed

It’s the bottom dial I can’t understand? So it just works on disconnection time but in milliseconds? So say I have no greater than 32A final circuits on TT which is 0.2 seconds then what do I set it?
No ---- take, spark I work with doesn’t know either and he’s just guesses where as I’d like to know how and why it’s set like that

 

[DPG]

But you were asking what delay a TT circuit should be set to. Are you saying you know this, but need to convert seconds to milliseconds?

To answer that, there are 1000mS in a Second.

 

[Deleted member 26818]

I think some clarification is needed.
Why are you installing this device, what is it intended to provide protection for?

 

[Yozza19]

It is a variable earth leakage modual that is used with a mccb eather bolted on or using a shunt trip module

The top part is to set trip current
Bottom is to set a time delay

They are mainly used on sub circuits or large motors ect were the time delay can offer some sort of discrimination

Remember earth leakage is cumulative

 

[Bradley6969]

But you were asking what delay a TT circuit should be set to. Are you saying you know this, but need to convert seconds to milliseconds?

To answer that, there are 1000mS in a Second.

Ok so it’s TT, in this panel you have Main MCCB/RCD one in picture then 3 X BS88 fuses which feed some electric boxes with 16A sockets with relevant 30mA RCBOs

 

[DPG]

I'm still confused. Do you not know what the regs require, or do you not get the seconds/milliseconds thing?

 

[Bradley6969]

It is a variable earth leakage modual that is used with a mccb eather bolted on or using a shunt trip module

The top part is to set trip current
Bottom is to set a time delay

They are mainly used on sub circuits or large motors ect were the time delay can offer some sort of discrimination

Remember earth leakage is cumulative

Thanks is there a way to understand how to set the time delay?

 

[Bradley6969]

It is a variable earth leakage modual that is used with a mccb eather bolted on or using a shunt trip module

The top part is to set trip current
Bottom is to set a time delay

They are mainly used on sub circuits or large motors ect were the time delay can offer some sort of discrimination

Remember earth leakage is cumulative

Thanks is there a way to understand how to set the time delay?

 

[Bradley6969]

I'm still confused. Do you not know what the regs require, or do you not get the seconds/milliseconds thing?

I’m not sure what the regs require? I know how to set trip current but not the trip delay

 

[westward10]

First you need to know what function it is required for. Secondly you need to consider upstream devices and how they are operating then the vigi module can be set to ensure coordination is achieved.

 

[Bradley6969]

First you need to know what function it is required for. Secondly you need to consider upstream devices and how they are operating then the vigi module can be set to ensure coordination is achieved.

It’s TT system so this is the upfront RCD, all there is down stream is 30mA RCBOs at boxes protecting sockets

 

[Bradley6969]

So top dial trip current I can set anywhere from 30mA to 10A
Bottom dial time delay I can set from nothing to 3 seconds

 

[Bradley6969]

So my final circuits are no greater than 32A on TT which is 0.2 seconds so I can set the trip delay to 0.3

 

[westward10]

What is the mccb which the module is fitted to supplying.

 

[Deleted member 26818]

So my final circuits are no greater than 32A on TT which is 0.2 seconds so I can set the trip delay to 0.3

No, of course not.
You have to set it to 0.2, or less.