Advice regarding inrush current please?

[HappyHippyDad]

I have just fitted 5 x 200w LED floodlights on the same switch.
I fitted 3 yesterday all worked fine. However the owner said they tripped once after I had left, no further info as to if they tripped immediately or after a while.

I have just fitted the last 2, the MCB is tripping immediately when the lights are switched on.

It also trips immediately when only 4 lights are connected.

At present they are on a type B 6A MCB.

The RCD does not trip and there is no fault to earth.

I had zero time to investigate and am returning in the morning.

My thoughts are.

1. Short circuit L-N
2. In rush current.

I know LED's can have a high in rush current, but could 3x200W LED floods (power factor 0.9) cause the MCB to trip? Could 4 or 5 cause it to trip with regards in rush current?

 

[SparkyChick]

It's most likely to be the inrush current for the drivers. Typically these are switch mode power supplies which have a fairly high inrush current due to the sizeable capacitors and inductors they contain.

Providing standard testing rules out things like shorts, IR faults etc. I would upgrade the MCB to a Type C.

 

[telectrix]

what size cable have you used? you could probably fit a 10A type C.

 

[Pete999]

I have just fitted 5 x 200w LED floodlights on the same switch.
I fitted 3 yesterday all worked fine. However the owner said they tripped once after I had left, no further info as to if they tripped immediately or after a while.

I have just fitted the last 2, the MCB is tripping immediately when the lights are switched on.

It also trips immediately when only 4 lights are connected.

At present they are on a type B 6A MCB.

The RCD does not trip and there is no fault to earth.

I had zero time to investigate and am returning in the morning.

My thoughts are.

1. Short circuit L-N
2. In rush current.

I know LED's can have a high in rush current, but could 3x200W LED floods (power factor 0.9) cause the MCB to trip? Could 4 or 5 cause it to trip with regards in rush current?

The Btype OCPD can't handle the current inrush, try a C type as SparkyChick and Tel have indicated posts 2 and 3

 

[Octopus]

Best check the R1 + R2 and the Ze and then fit the "best" MCB you can .... Tel's suggestion of a 10A type C is probably the way to go.

Do the MI's say anything about the limit on a circuit?

Is this the site where the client wants another 5 fitted?

 

[Andy78]

As above, refer to the manufacturer re expected inrush current.

I'm yet to experience this phenomenon myself to be honest. Most led I have connected to one switchway was 6 x 200W hi-bays and a B6 didn't bat an eyelid.

Hence I have never used an inrush current limiting device, but I do know they exist if you are still experiencing problems after trying a C curve device.

 

[HappyHippyDad]

what size cable have you used? you could probably fit a 10A type C.

I've used 6mm SWA due to the VD.

Best check the R1 + R2 and the Ze and then fit the "best" MCB you can .... Tel's suggestion of a 10A type C is probably the way to go.

Do the MI's say anything about the limit on a circuit?

Is this the site where the client wants another 5 fitted?

Nothing on the MI's about the limit on the circuit Murdoch.
Yes, there will be another 5 lights next year!

As above, refer to the manufacturer re expected inrush current.

I'm yet to experience this phenomenon myself to be honest. Most led I have connected to one switchway was 6 x 200W hi-bays and a B6 didn't bat an eyelid.

Hence I have never used an inrush current limiting device, but I do know they exist if you are still experiencing problems after trying a C curve device.

How does an inrush current limiting device work and how is it fitted Andy? Just incase I still have trouble with a 10A type C when the next 5 lights are fitted?

 

[Andy78]

How does an inrush current limiting device work and how is it fitted Andy? Just incase I still have trouble with a 10A type C when the next 5 lights are fitted?

Like I said, I've not used any, so you're asking the wrong fella. Just gave it you as a point of research really.

 

[HappyHippyDad]

Like I said, I've not used any, so you're asking the wrong fella. Just gave it you as a point of research really.

Cheers Andy, sorry for putting you on the spot.

 

[Octopus]

Nothing on the MI's about the limit on the circuit Murdoch.

Yes, there will be another 5 lights next year!

I would be researching the MI's for guidance - and if nothing is forthcoming you need to "prepare" your client for a higher bill as you will need to use a separate circuit for the next 5 lights

 

[Pete999]

I have just fitted 5 x 200w LED floodlights on the same switch.
I fitted 3 yesterday all worked fine. However the owner said they tripped once after I had left, no further info as to if they tripped immediately or after a while.

I have just fitted the last 2, the MCB is tripping immediately when the lights are switched on.

It also trips immediately when only 4 lights are connected.

At present they are on a type B 6A MCB.

The RCD does not trip and there is no fault to earth.

I had zero time to investigate and am returning in the morning.

My thoughts are.

1. Short circuit L-N
2. In rush current.

I know LED's can have a high in rush current, but could 3x200W LED floods (power factor 0.9) cause the MCB to trip? Could 4 or 5 cause it to trip with regards in rush current?

https://www.mouser.co.uk/new/amphen...MI3_WfkqfZ3QIVg73tCh3DTgoREAAYASAAEgKcovD_BwE

 

[plugsandsparks]

Its very difficult even if you have the data, i have MIs quoting very very high inrush but for a very small time like 2mS etc but the current can be 60A for a small led light. Trying to work out the profile is too hard as you dont have the decay rate, just a peak which is often massive. I find trial and error works best, for MCBs go high and sluggish, like Cs and Ds. For relays or any switching device, use industrial strength relays or contactors. This is after a few years going back replacing presence detectors, dusk til dawn sensors and lightwave RF relay boxes.

 

[SparkyChick]

How does an inrush current limiting device work and how is it fitted Andy? Just incase I still have trouble with a 10A type C when the next 5 lights are fitted?

I don't know for sure as I've never used one or researched one, but I suspect it's akin to a dimmer that gradually ramps up the voltage when first powered on (like the vPro dimmer modules).

By doing this, the capacitors and inductors on the input stages of the drivers have a chance to charge up to supply voltage slow and steady rather than the huge wallop you get from charging them up from nothing to 240v in an instant.

This is one of the benefits of switch mode drivers as typically many of them are capable of delivering full output load at a very wide range of input voltages.

 

[Andy78]

Cheers Andy, sorry for putting you on the spot.

Ha ha, no worries, just sorry I can't help more.

 

[Andy-1960]

This is a data sheet for a Meanwell 200w LED driver which is a popular unit used by quite a number of manufacturers.
I would imagine characteristics are similar for other brands.
They suggest 4 units on a 6A type B or 6 units on a 6A type C

ELG-200-MEAN WELL Switching Power Supply Manufacturer - https://www.meanwell.com/webapp/product/search.aspx?prod=ELG-200