Circuit Blowing Bulbs - Overpowered?
Circuit Blowing Bulbs - Overpowered?
(OP)
Hi,
I'm in the process of repairing a DJ light system with a knackered transformer. It was causing the internal fuses to blow, so i've replaced the transformer, but it's now taken to blowing the bulbs within it. I'm guessing this is due to too high a voltage, or too much current flowing, but I just need to understand exactly what the ratings I have mean.
The transformer is identical to the old one in rating. 240V input to 2 x 24V secondary outputs, in series to create 48V. I've already noticed that this is actually producing 52V with no load attached. The transformer is 300VA, used to power two 150W 24V bulbs, also in series.
When a transformer is rated at 300VA, does that mean, when it's supplying 48V on the secondary, that it will supply 6.25A, or that this is the maximum it can supply? Also, how sensitive are halogen bulbs to a couple of volts difference to the rating? If it would work, I could get hold of higher rated bulbs, but I'm not sure whether to go for the same voltage rating, but a higher wattage, or to go for the same wattage with a higher voltage?
Hope that makes sense
Cheers
I'm in the process of repairing a DJ light system with a knackered transformer. It was causing the internal fuses to blow, so i've replaced the transformer, but it's now taken to blowing the bulbs within it. I'm guessing this is due to too high a voltage, or too much current flowing, but I just need to understand exactly what the ratings I have mean.
The transformer is identical to the old one in rating. 240V input to 2 x 24V secondary outputs, in series to create 48V. I've already noticed that this is actually producing 52V with no load attached. The transformer is 300VA, used to power two 150W 24V bulbs, also in series.
When a transformer is rated at 300VA, does that mean, when it's supplying 48V on the secondary, that it will supply 6.25A, or that this is the maximum it can supply? Also, how sensitive are halogen bulbs to a couple of volts difference to the rating? If it would work, I could get hold of higher rated bulbs, but I'm not sure whether to go for the same voltage rating, but a higher wattage, or to go for the same wattage with a higher voltage?
Hope that makes sense
Cheers





RE: Circuit Blowing Bulbs - Overpowered?
Are there taps on the transformer for adjusting the turns ratio?
RE: Circuit Blowing Bulbs - Overpowered?
RE: Circuit Blowing Bulbs - Overpowered?
49V out
guessing the output changed due to fluctuations in the mains input.
RE: Circuit Blowing Bulbs - Overpowered?
The current has no control. The bulbs will draw what they want. The higher the load the lower the voltage though.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Circuit Blowing Bulbs - Overpowered?
RE: Circuit Blowing Bulbs - Overpowered?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Circuit Blowing Bulbs - Overpowered?
As the load is increased from 0 to 6.25A the output voltage will decrease to the nominal voltage.
RE: Circuit Blowing Bulbs - Overpowered?
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Circuit Blowing Bulbs - Overpowered?
http
Other factors like vibration and frequent on/off also have something to say. And some bulbs are inferior quality.
Gunnar Englund
www.gke.org
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RE: Circuit Blowing Bulbs - Overpowered?
I was wrong. The life of an incandescent filament is approximately inversely proportional to V16.
Far worse than I remembered.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Circuit Blowing Bulbs - Overpowered?
Incandescent lamps are very sensitive to changes in the supply voltage. These characteristics are of great practical and economic importance. For a supply voltage V,
Light output is approximately proportional to V^ 3.4
Power consumption is approximately proportional to V ^1.6
Lifetime is approximately inversely proportional to V ^16
Color temperature is approximately proportional to V ^0.42
So lifetime changes with sizteenth power !!!
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RE: Circuit Blowing Bulbs - Overpowered?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Circuit Blowing Bulbs - Overpowered?
A 240/48V transformer operating at full rated power with a resistive load produces 49V output with 226V input? Sounds like this isn't a 240/48 transformer but a 220/48V transformer. Output voltage should be close to nominal when running at nameplate conditions, i.e. rated voltage delivering rated current. This one isn't.
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RE: Circuit Blowing Bulbs - Overpowered?
I'm no electrician, but for the initially given bulbs it seems necessary to add loads, so a proper supply would be 13A minimum @ 24V.
RE: Circuit Blowing Bulbs - Overpowered?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com