Pool chlorinator - what does the triac do?

Nov 18, 2012 2 Replies

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Trevor Wilson

That is certainly easy enough to check. TRIACs usually fail catastrophically. I've seen this system before. It's slightly odd, but it works. Yup. To switch off the juice, if there is insufficient water/salt solution running through the cell. Correct. To test, you need to supply…

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Spuckle 13 years ago

I've got a dud Monarch salt water pool chlorinator - no output.

It looks like the triac on the output has failed.

The circuit layout is:

AC ==> Dimmer ctrl ==> Xformer ==> Bridge rectifier ==> Triac ==> Cell

The output triac appears to have failed open. Its an ST branded BTA40.

The triac switches the -ve lead to the cell, the gate is connected directly to a "stud" electrode in the cell.

What's the purpose of the triac?

Seems to me if the cell has water in it the triac is "on", otherwise its "off". I dont have the full cell assembly - is the stud at the top so it cannot run unless the cell is completely full??

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Trevor Wilson 13 years ago

**That is certainly easy enough to check. TRIACs usually fail catastrophically.

**I've seen this system before. It's slightly odd, but it works.

**Yup.

**To switch off the juice, if there is insufficient water/salt solution running through the cell.

**Correct. To test, you need to supply a load to the unit, such that at least 10 Amps flows (I used a roll of speaker cable, shorted at one end. Connect the gate to the positive supply through a (say) 330 Ohm resistor.

Trevor Wilson www.rageaudio.com.au

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