Type B rcbos and inrush current

[Newtothis]

Does any one have a rough idea how many 24w led panel 600x600 could go on a 10 amp type b rcbo with out tripping or a 6 amp type B rcbo

I found a long circuit that complies with zs when a direct measurement is taken at its furthest point , but on length alone im sure it does not comply by calculation of zs but VD is okay

 

[pc1966]

The accurate calculation for LED lights is complicated as you need to know the driver's inrush characteristics and the MCB/RCBO trip for very short current spikes (lower then the usual few milliseconds for other cases). This site has some examples:

Learning Center - Application note - How to choose the right circuit breaker | eldoLED

When switching on an LED lighting system and nothing happens, the inrush currents of the LED driver triggered the circuit breaker. Read more.

www.eldoled.com

They get 8 * 100W drivers on a 16A B curve, so roughly a quarter of what you might expect from steady state. Going to a C-curve should roughly double that (so about half of steady state limit), but again it depends on behaviour a little out of the typical datasheet characteristics.

The volt drop only needs to be OK for the nominal load, not the inrush current. In fact, sometimes having that reduced by series resistance is a good thing - it saves on switches/contactors getting burnt contacts!

You can even go further and use a NTC (negative temperature coefficient) thermistor to reduce inrush current then to allow more or less full voltage when it has heated up:

How Do You Choose The Right Type Of NTC Thermistor To Limit Inrush Current For Capacitive Applications?

Matt Cuhadar from the Ametherm team answers a reader question about choosing the right type of NTC Thermistor to limit inrush current for capacitive applications.

www.powerelectronics.com

 

[davesparks]

Call the technical support department of the manufacturer of the RCBO, they should be able to tell you what you need to know.
[automerge]1598133343[/automerge]

I found a long circuit that complies with zs when a direct measurement is taken at its furthest point , but on length alone im sure it does not comply by calculation of zs but VD is okay

If the actual measured Zs is compliant then what is the problem?
What value have you calculated for it and how much of a difference is there between this and the measured Zs?

 

[Newtothis]

Call the technical support department of the manufacturer of the RCBO, they should be able to tell you what you need to know.
[automerge]1598133343[/automerge]


If the actual measured Zs is compliant then what is the problem?
What value have you calculated for it and how much of a difference is there between this and the measured Zs?

calculated is 110x 0.0302 = 3.322ohm
Measured is 1.5 ohm
1.5mm 10 amp type c
load is about 400w evenly spread give or take vd of about 5.8 v

 

[Vortigern]

Manufacturers data is available online for inrush currents for their products, as already stated by @davesparks however some control gear shows inrush currents of amazing amounts like 320 amps. I have watched a laboratory measurement of this IC and the duration of each light is circa 500 ms. However it is somewhat mitigated by the fact that not all lights draw simultaneously so the total draw is somewhat staggered which may account for the fact that in theory the total inrush current on 8 LED panels I installed would be something crazy like 300 A. But did not trip a type B MCB. You can get inrush limiters. Also one aspect that can be forgotten is the switching and if there are relays they can burn out and even fuse if not rated for the load on occasion.

 

[davesparks]

Manufacturers data is available online for inrush currents for their products, as already stated by @davesparks however some control gear shows inrush currents of amazing amounts like 320 amps. I have watched a laboratory measurement of this IC and the duration of each light is circa 500 ms. However it is somewhat mitigated by the fact that not all lights draw simultaneously so the total draw is somewhat staggered which may account for the fact that in theory the total inrush current on 8 LED panels I installed would be something crazy like 300 A. But did not trip a type B MCB. You can get inrush limiters. Also one aspect that can be forgotten is the switching and if there are relays they can burn out and even fuse if not rated for the load on occasion.

Cable length can also affect inrush

 

[Newtothis]

Cable length can also affect inrush

in what way?

 

[pc1966]

It is not so much the cable length as the resulting resistance. Though for very short spikes the inductive (and capacitive, oddly) part can play a role in limiting the inrush due to the added supply impedance.

 

[GBDamo]

I had 72 x 20W floods, light fitting MI stated, basically one fitting per Amp of a C type breaker.

So 6 on a C6, 10 on a C10 etc..

Seemed massive overkill.

Ended up with 9 C6 circuits, mostly with 6 on and some with 9.

Bit of a mix of MI and experience.

Manufacturers will always err on the side of caution.

I designed the circuits such that they could be split down if there were any inrush tripping issues.

 

[Newtothis]

I had 72 x 20W floods, light fitting MI stated, basically one fitting per Amp of a C type breaker.

So 6 on a C6, 10 on a C10 etc..

Seemed massive overkill.

Ended up with 9 C6 circuits, mostly with 6 on and some with 9.

Bit of a mix of MI and experience.

Manufacturers will always err on the side of caution.

I designed the circuits such that they could be split down if there were any inrush tripping issues.

this is the panel 12 of the 23w MODLED LG - High performance backlit module with VDT optic | Tamlite Lighting United Kingdom - https://www.tamlite.co.uk/product/modled-lg but i cant seem to find much info on it?