inverter keeps cycling

[gerty]

I had a truck driver come by my classroom last week, said he had a disco in the back of his truck. He has a 35' or so box truck with 8 two tube 40watt flourescent lights, all powered from a 1500 watt inverter. Problem is , when he turns them on they cycle off and on at about 2 hz.
The dealer wired them all back to one plug which stays plugged in, the switch turns on a heavy duty realy (looks like a starter solenoid) on the primary of the inverter. The first thing I did was turn off two fixtures (they each have thier own switch) and turn on the power, the others lit without blinking. If I turn on the last 2 fixtures after the initial surge , they work also.
I 'm wondering if the inverter see's all the ballasts as dead shorts,and goes into a restart mode. Or is there too much inductance for the inverter to handle all at once, if that's the case would I need to add some resistance to the load ?

The driver said he stays on the road and wouldn't be able to come back for a while, so I'm going to have a hard time trying any fixes. Driver also tried 2 other inverters,one was a 3,000 watt and all had the same result...
What'dya think...

 

[Leftyretro]

I had a truck driver come by my classroom last week, said he had a disco in the back of his truck. He has a 35' or so box truck with 8 two tube 40watt flourescent lights, all powered from a 1500 watt inverter. Problem is , when he turns them on they cycle off and on at about 2 hz.
The dealer wired them all back to one plug which stays plugged in, the switch turns on a heavy duty realy (looks like a starter solenoid) on the primary of the inverter. The first thing I did was turn off two fixtures (they each have thier own switch) and turn on the power, the others lit without blinking. If I turn on the last 2 fixtures after the initial surge , they work also.
I 'm wondering if the inverter see's all the ballasts as dead shorts,and goes into a restart mode. Or is there too much inductance for the inverter to handle all at once, if that's the case would I need to add some resistance to the load ?

The driver said he stays on the road and wouldn't be able to come back for a while, so I'm going to have a hard time trying any fixes. Driver also tried 2 other inverters,one was a 3,000 watt and all had the same result...
What'dya think...

You probably got it correct, start-up surge for all the ballasts are too much load for the invertor. A simple fix might be installing adjustable on delay timer relays so that the lamps start up in a staggared delay, say 5 seconds for second set, 10 for 3rd, 15 for 4th, etc.

Lefty

 

[crutschow]

You probably got it correct, start-up surge for all the ballasts are too much load for the invertor. A simple fix might be installing adjustable on delay timer relays so that the lamps start up in a staggared delay, say 5 seconds for second set, 10 for 3rd, 15 for 4th, etc.

Sounds like a good solution.

Since he only had to turn off two fixtures to get it to start properly, he could probablly get by with just one or two delay relays.

 

[mneary]

I've seen other electronic controls have trouble with very low power factors (highly inductive loads). Could you try adding a moderate (60W) incandescent bulb? Although it increases the load it could damp other side effects.

 

[ecerfoglio]

I've seen other electronic controls have trouble with very low power factors (highly inductive loads). Could you try adding a moderate (60W) incandescent bulb? Although it increases the load it could damp other side effects.

Or you can correct the power factor adding a capacitor in parallel with the load (or one inside each fixture).

With a higher power factor (say 0.80) the load will use less current

 

[stevez]

Could electronic ballasts be a potential solution? I know little about the power factor and surge. While ballasts aren't cheap they might be a simple and reliable solution.

 

[gerty]

Thanks for the replies, my first suggestion to the driver(who is also the owner)was to run two switch legs. Each leg to turn on half the lights.
The driver is tighter than bark on a tree and won't spend anything to fix it now that he knows he can just pull a chain on two fixtures. I was hoping he'd bring the truck back so that I could try adding so resistance or capacitance to the circuit to see what would work best.