triac problems..

[dacflyer]

i have a high current power pack, used for controling lights, via a light controller, like used in night clube for stage lighting /
its a 4 channel controller, its obviously designed for resistive loads only. because if i use any light with a transformer in it
( canned low voltage spot lights ) they blow the fuses, because of the transformer bucking...
is there any mod i can possibly do so that it will work with induction as well as with resistive ?

[russlk]

Take a look at the February Nuts & Volts, an article by Ray Marston shows how to connect a snubber across the triac.

[MrAl]

Hi dac,<p>Usually, you shouldnt use a triac controller
with inductive loads like transformers.
A variac might help, although they are a bit
pricy.<p>Russ:
Was that article mainly for reducing dv/dt,
or did it specifically say for driving transformers?<p>--Al

[dacflyer]

hi, the controller is connected to a light controller , it works high current lights fine
( bright / dimming / flashing etc )
but there are other lights that use transformers
( pin spots / ropelights etc )
when these are used , the transformers buck, causing fuse to blow , i am looking for something to prevent this if at all possible..

[dacflyer]

will this snubber prevent the transformers from bucking? the controller makes this power pack bright / dim / flash etc,
the controller is pretty complex, but basically it sends a signal to the power pack which works the triacs..

[L. Daniel Rosa]

I wouldn't be so quick to suspect the inductance of blowing the fuses. Light bulbs have a much lower resistance when cold than when hot. Low voltage lighting may have marginal wiring which will incrrease the warming-up interval. Multiple low voltage bulbs in parallel may be drawing too much of a surge for the fuses to accept that everything's okay.<p>Try measuring the cold resistance of the lighting circuit with the transformer disconnected. Use this to determine the startup curent. You may need to use another transformer and split the load.

[Chris Smith]

If you have a control unit and you plug it into another control unit, [low votage transformer] each stage has a loss of up to 1/3 of the total amps in wasted energy called loss. Perhaps your not taking this into consideration when you place a fuse into your unit. Saturation into the second transformer is like a fly wheel and it wont react instantly and will equal a load much greater than the running current. Like a fridge that starts, it may require amperage in the ten fold range on the surge of start up, yet it will still drop back to minimal amperage while running. You may want to replace the heavy winding transformers with switching transformers that are today standards for power. If its safe to do so, increase your fuse by 1/3 or drop your load by one third, and see if it still pops the fuse? Standard Bucking at 60 hertz should never be a problem because all units and transformers are already designed to handle these factors. If you still feel that bucking is a problem, use a saturation core transformer and this will absorb transients and hold down all major surges in either directions. But the saturation core transformer cant be switched at high rates as this will tend to have even a slower response than the standard transformer. Unless your high speed switching or doing major on/off power loads, buck will not blow a fuse because they too have these factors built in when they were designed and mostly can compensate for them. Also use slow blow fuses instead of normal ones. Also some transformers are designed for full voltage only due to the saturation ratio, and may draw 10 amps at voltages of say 20 volts, while drawing only one amp at 120 volts. Many lighting transformers that I have tested/started at low voltages using a variac, appear to be a dead short at low voltage, yet still work fine at full volts. This may be your surge factor of over draw.<p>[ February 08, 2002: Message edited by: Chris Smith ]</p>

[dacflyer]

its not the lights,, the transformers work good if its a slow on / off feature. but if they are fast flashing, the transformers growel heavely then the fuzes blow,,

[toejam]

a simple solution may be to wire the flashing circut to bypass the triac when activated. A zero crossing circut modification might work.
tj

[Chris Smith]

If the transformers growl, and circuits pop, IT IS the inductance. Those transformers are not designed for any thing but full power. I'd switch over to low inductance "Switching Power Supplies".

[mikem]

Switching the primary of a transformer on and off is hard on equipment. The inrush current is very high the power is applied and the kickback is bad when the primary is de-energized. I would switch to 120V lights and forget the transformer lights. I sell these for a living and have had many bad experiences just like yours.

[dacflyer]

hi, finnaly i got someone that knows what i am talking about .<p>the light i am using need to have the transformer,because they are....NEON<p>so is there really no way to solve this problem.....or is it not really possible?

[mikem]

Hey Dac:
You are trying to use Neon lights with a triac type dimmer pack? Two things to consider: Use a relay type controller like the American DJ SC8FC system which is a hard wired remote contoller with 8 relay channels and a 25 foot control cable.(about $135). Or as a homebrew fix, control the neon transformer with a 120V power relay with the coil connected to the dimmer pack. When the voltage gets high enough to close the relay, the neon lights. The kick-back of the relay coil should be much less than that of the neon transformer, probably not enough to cause problems.--Mike

[Chris Smith]

If you want full help on this board, you might try using the full description of what you want. I read all your posts, and no mention of neon was there. Neon doesnt need a transformer, and you could have saved a lot of posts the touble if this was your original goal?

[dacflyer]

thats alright, but won't help for dimming purposes<p>the controller that controls the triac pac
has many functions...flashing / dimming etc.
its got many patterns as well as one of the best color organs i've ever seen.except here they call the color organ a audio processor... thanx anyway.