I have one of those 1500 watt radiator style portableelectric heaters. Love itHowever, rather than the built in thermostat turningthe unit OFF?ON every 15 min's or so, I was thinkingit would be more efficient to use an SCR dimmer controlto vary the amt or power it gets?Does anyone know of an SCR control hefty enough tohandle this kind of resistive heating load??

Ive built them before. Check with someone who sells stage lighting.They have some humongous dimmers.Jimmie

:lace the triac=A0For example, a 800V 16AHere:Lutron C-2000 Centurion Rotary On/Off Dimmer Large Control 2000W$88 each, How much easier could it be? There's also a Centurionversion for $63, 2000W.

SCR dimmer control for portable electric heater??

Mar 21, 2010 68 Replies

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Don Klipstein 16 years ago

example, a 800V 16A

That is indeed only negligibly true, at least in general, with semiconductors other than MOSFETs and Schottky diodes, as long as you stay within a specific general chemistry (such as silicon as opposed to silicon carbide or germanium or gallium arsenide).

(Actually, this voltage drop variation with voltage rating is slightly true with bipolar transistors. 1000 volt bipolar transistors have significantly higher saturation voltage and generally less gain than ones rated 60 volts or less.)

I expect negligible to minimal difference in voltage drop between a 200 volt triac and a 600 volt one.

- Don Klipstein ( snipped-for-privacy@misty.com)

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dean 16 years ago

lace the triac

=A0For example, a 800V 16A

Here:

Lutron C-2000 Centurion Rotary On/Off Dimmer Large Control 2000W

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$88 each, How much easier could it be? There's also a Centurion version for $63, 2000W.

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Stormin Mormon 16 years ago

A variac is a variable transformer. Different than a resistor.

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Joe 16 years ago

Actually, no. Variacs are autotransformers, just like the tapped coil distribution transformer hanging on the pole outside your house. Their power losses are minimal, and they operate serenely and fuss free just supplying the voltage you dial in. Most can even supply 0 - 140 V if you need it. I keep one in my shop for calming down my monster soldering iron when working on more delicate projects. I've never found it to be even slightly warm after use. Variacs and Powerstats are used universally in chemical laboratories for controlling reactor flask heaters and such. In those environments, stray heat would be a safety problem. The Variac therefore is the best solution, IMO to the OP's problem from simplicity and cost standpoints.

Joe

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clare 16 years ago

RMS on a sine wave, yes - but a chopped sine wave responds differently.

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me 16 years ago

Thanks so much Joe!!

I learned something I didn't know today!

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JIMMIE 16 years ago

=A0For example, a 800V 16A

I dont know how practical modifying a dimmer would be but the idea is good. I have made some big ones like that and the only difference between a 300 watt one and the 2000 watt dimmer is the size of the triac.

Jimmie

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JIMMIE 16 years ago

In my opinion the OP doesn't have a problem. I was just willing to suggest a way to do what he wanted to do. I don't agree he needs to do it.

Jimmie

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Tony 16 years ago

A melting SCR? Somewhere there should have been a fuse.

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