[SOLVED] Driving contactor coil with dimmer

[adnan_merter]

Hello everybody, first i apologize if this a repetitive question, i checked the forum and couldnt see a relevant topic.

Recently i bought a contactor for my project but accidentally i bought one with a 24vac coil instead of 220vac coil. I tried to exchange it but no luck.

I have an option buying 220/24vac transfomer but if possible i would like to use a dimmer circuit. The coil draws not more than 1 amp.

 

[barry]

I'd be really reluctant to try and use a dimmer here. A dimmer does not lower the voltage, it only turns the AC off for part of the cycle. Plus, standard light dimmers are not designed for inductive loads.

 

[adnan_merter]

I'd be really reluctant to try and use a dimmer here. A dimmer does not lower the voltage, it only turns the AC off for part of the cycle. Plus, standard light dimmers are not designed for inductive loads.

Thanks for reply, i know dimmer doesnt lower the voltage, it changes the on/off time, thus changes total energy consumed over time. I can design a new dimmer circuit with snubber for inductive loads.

The question is, can the coil endure peak voltages in a short while?

 

[KlausST]

Hi,

The question is, can the coil endure peak voltages in a short while?

I doubt any one here can give you a guarantee.
All we can do is guess. Since we even don´t know which motor from which manufacturer.

The only way for you to get reliable informations is to:
* read the datasheet if there is an according specification
* or contact the manufacturer.

Klaus

 

[adnan_merter]

Hi,

I doubt any one here can give you a guarantee.
All we can do is guess. Since we even don´t know which motor from which manufacturer.

The only way for you to get reliable informations is to:
* read the datasheet if there is an according specification
* or contact the manufacturer.

Klaus

I guess the only way to know if it is possible or not, is experiment it.

I will try tomorrow and let you know the result. Thank you.

 

[KlausST]

Hi,

I don´t agree.
An experiment is no valid test.

I´m rather sure that a properly designed triac circuit will work ... but there are safety regulations. You can´t test them. Safety isolation, clearance ...
And if it works for 5 minutes it does not mean it will work for years. I expect higher mechanical stress, maybe higher noise ... maybe higher wear out of isolation...

Klaus

 

[adnan_merter]

Hi,

I don´t agree.
An experiment is no valid test.

I´m rather sure that a properly designed triac circuit will work ... but there are safety regulations. You can´t test them. Safety isolation, clearance ...
And if it works for 5 minutes it does not mean it will work for years. I expect higher mechanical stress, maybe higher noise ... maybe higher wear out of isolation...

Klaus

I understand your concerns but i will use it to power my personel workbench, neither commercial nor critical application, and i will always be there when the coil is energized. I totally agree with you, i expect noise because of switching. It will be just an experiment not a suggestion or tutorial.

 

[dick_freebird]

A 24VAC line transformer ought to be dirt cheap and
common at electrical / electronic surplus (incl eBay).

HVAC controls commonly use 24VAC to run the hot
side (compressor, fan, solenoid valve) relays so you
can probably find new and not-expensive at home
supply and hardware stores.

 

[wwfeldman]

your jury rigged gadget will probably work for a (short) while
and blow up when you can least afford it

you are much better off getting a step down transformer
and learning a lesson on ensuring that what you buy is what you want.

 

[adnan_merter]

your jury rigged gadget will probably work for a (short) while
and blow up when you can least afford it

you are much better off getting a step down transformer
and learning a lesson on ensuring that what you buy is what you want.

Thanks for advice Lesson already learnt. I am new at power electronics and getting experience from mistakes. But for sake of curiosity i will try dimmer and for long term operation i will order a transformer. Case closed.

 

[KlausST]

Hi,

An autotransformer could do if you don't need isolation.

Klaus