switching ballasts

davelerave · Sep 17, 2011

can someone clear this up for me?

is switching electronic ballasts more severe on contacts than switching magnetic?

and also according to this spec
Steinel
it can switch 8 electronic ballasts max

or 500watt of standard(low-frequency with cap) fluorescent lighting

do i have that right ?for magnetic -you add the wattage but don't need to count ballasts

thanks

Marvo · Sep 17, 2011

The 8 electronic ballasts you refer to are highly capacitive so their PF will be a big issue for switching if uncorrected. They stipulate the magnetic ballasts at a pf of 0.5.

I would just add the wattage for whatever lighting you're using and decide which category it falls under to make sure you're not overloading the switch.

You could always do the customer a favour and add some pf correction to bring the load back to linear.

MarkieSparkie · Sep 18, 2011

Hi Dave, the short answer to your question is NO. Magnetic ballasts are inductive, whereas electronic ballasts are capacitive, either can cause adverse effects to switching contacts, eg. burning and erosion, if the reactance is high enough and uncompensated and/or the contacts unprotected by snubber networks.
It is generally accepted good practice to allow 20% "headroom" on any fluorescent lamp/switch gear loading to maximise longevity of the switching device. For example say the manufacturer of the switching device says the device will switch 500W of CFLs uncompensated, then the actual maximum load I would design for would be 500W x 0.8 = 400W to ensure reliability.