Dimming load- How to work it out?

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Hi

How do i work out what the dimming load it's a total load of 8x GU10 lamps.

I need to know if say when they are 10-15% they are not going to under load my dimmer pack.

Is it as simple as 400W minus say 90% for 10% of light

A bit more info
The dimmer is a Strand Tempus Dimmer pack
http://www.strandarchive.co.uk/control/tempus/tempus.html
6 channels- 40W MIN load
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Hi

But when it dims doesn't it reduce the amount of amps going in to the lamp thus decreasing the load in watts

I think i might have done it now.

Thanks
Jake
 
Amount of light is not linear to power delivered so at 10% of power likely near zero light output.

Looked at unit and it does not really define what the 40W refers to. Likely it is the load at supply voltage. With thyristor switching although average load may fall as the light is dimmed the thyristors are still switching full load.

Any Quartz halogen bulb will not like running cool and dimming them will shorten their lives.

Idea is the very hot envelope will not allow the tungsten to be deposited on it so it will re-deposit it onto the tungsten element. However the re-deposit will not be even so in the end the lamp will blow. But with a cold envelope the quartz will go black and the bulb will blow premature.

So your 8 lamps will reduce very quickly as they blow so really you need to consider it with less than 8 lamps.

To reduce light without changing colour it is better to control the number of lamps in use rather than dim the whole series of lamps.
 
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Hi

Amount of light is not linear to power delivered so at 10% of power likely near zero light output. l

10% is warmers- Warm the light up before use.

Looked at unit and it does not really define what the 40W refers to. Likely it is the load at supply voltage. With thyristor switching although average load may fall as the light is dimmed the thyristors are still switching full load.

I believe that the 40W min load is per channel.
Oh ok i didn't know that, it seems a bit odd though.

[code:1]Any Quartz halogen bulb will not like running cool and dimming them will shorten their lives.

Idea is the very hot envelope will not allow the tungsten to be deposited on it so it will re-deposit it onto the tungsten element. However the re-deposit will not be even so in the end the lamp will blow. But with a cold envelope the quartz will go black and the bulb will blow premature. [/code:1]

OK, I could probably find some different fitting that take a normal tungsten bulb.
It's for a one night event so as long as they last the night all will be fine.
They will spend most of there time chasing and less dimming. I was just checking to be honest.


[code:1]So your 8 lamps will reduce very quickly as they blow so really you need to consider it with less than 8 lamps.

To reduce light without changing colour it is better to control the number of lamps in use rather than dim the whole series of lamps.[/code:1]
How many lamps would you recommend.

we don't have enough channels for every lamp on there own circuit.
there are a total of 24 fitting but each channel of the dimmer has 8 cans on it.

No it does not reduce the amps. It reduces the time the amps flow for.

I was just going by what my amp meter was saying.
 
I think you'll struggle with a normal ammeter with modified sine waves.
As it is a stage dimmer pack designed for use with high power lamps I don't think you'll have an issue as long as you do not exceed the rating i.e. 10A per channel (using the wattage divided by supply voltage) and the supply loading.
Those dimmers however are a bit ancient! Not sure if they will have pre heat.
 
HI

I think you'll struggle with a normal ammeter with modified sine waves.
As it is a stage dimmer pack designed for use with high power lamps I don't think you'll have an issue as long as you do not exceed the rating i.e. 10A per channel (using the wattage divided by supply voltage) and the supply loading.
Those dimmers however are a bit ancient! Not sure if they will have pre heat.

The reading seemed stable, but when fading it did go a bit mental.
Good, hope fully not, problems is the last thing i want.

Yes they are very old They don't have any pre-heat function.
Thats why we pre-heat it via the lighting console before the start of a show thus the question will they be ok at 10%. Which from what i've read they will be fine the lamps seem the be the problem now.

Thanks
Jake
 
The tempus will be fine with between one and fourty 50W GU10s per channel, although if you're using the dimmer pack with 5A sockets, you are limited to twenty lamps per socket.

The minimum loading refers to the wattage of all the lamps connected to a dimmer channel that is required to allow the dimmer to function. If it has a 40W minimum load requirement then a 50W load will be fine. It doesn't matter what level the dimmer output is at, as long as there is at least 40W connected it will be happy.

If you underload the dimmer, the worst thing that will happen is it will not dim proprly, or at all. It won't do any damage tot he dimmer.

Your lamps will be fine as long as you manually pre heat them from the desk when you first power the rig up.
 

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