Inrush current and cable size 1

[oresakri]

Hello!

I designed an outdoor LED Street Lighting with 8 poles, 2kW total. When sizing the cable I chose to use a 5x10mm2 cable (for voltage drop). Each pole has two lamps with the following data.

Power consumption at dimming:120 W
Inrush current: 47.2 A
Inrush time: 600 ms
Driver current: 700 mA
Power Factor: (Nom) 0.95

Should i take into account also the inrush current or the inrush time is too small?

Please, can someone advise on the above?

 

[itsmoked]

2kW/230V = 9A

Have you already bought the LED drivers?

You will have problems with 16 x 47A = 750A of inrush.

You should use soft-start drivers to spare yourself lots of problems.
The drivers don't often care about limited available charging current but what happens is the breakers trip frequently and if you up size the breaker too far the wiring ceases to be protected.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[itsmoked]

If you already have the drivers I suggest you run smaller wire and 3 separate circuits. This reduces the inrush to something manageable by reasonably sized breakers.

Check the driver documentation as it may suggest the maximum number of drivers per circuit.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

You may consider individual photo cells on each pole. That will avoid simultaneous inrush.
Keith, how will LED drivers respond to stepped energization through a limiting resistor?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ScottyUK]

Cable impedance will go some way toward calming down that inrush. 600ms inrush will definitely wake the breaker up, but that's a long duration for such a high inrush on what is quite a small load. Are you sure those values are accurate?

 

[itsmoked]

Most drives don't really care on the inrush as it's just charging some big cap. The photo cell idea I like. Only thing is, how do they do with charging caps as compared to lighting up ol'HID inductive ballasts?

As Scotty sez that seems a bit long for that big an inrush. Typically the inrush is about 30% bigger than the 47A listed above but only for about one millisecond.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

Inrush = 47.2 Amps
Operating Current = 0.7 Amps
Inrush = x 67
That's a little higher inrush ratio than we usually see with other equipment.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[oresakri]

I am planning to use CoreLine Tempo BVP120 LED120/NW S. Total distance is about 700m. Already, i have 3 separate circuits, but if i use smaller wire maybe will cause problems with voltage drop.

 

[itsmoked]

oresakri; A couple of things.

1) The stated INRUSH time on the data sheet is flat wrong. It is not 600ms it is 600us.
2) I suspect the BVP120 is obsolete because Phillips has no sign of it on their website. Instead they have the BVP125.

I'd suggest you go with that one because it's fully specified unlike the unmentioned BVP120.

The installation sheet for the BVP125 clearly states circuit size and circuit luminaire limits.

This found at Phillips BVP125 Installation Manual

Note they spec the breaker size and curves which is invaluable in your situation. You need only size the wire to support the running current over the distance compatible with the selected breaker. I'd tend towards "C" curve for long wire runs.


Keith Cress
kcress -

http://www.flaminsystems.com