[joeavaerage]

Hi,

The voltage to turn the relay on will be 12 volt dc (max 50mA).

The load I'm trying to turn on is 120ac for a small coolant pump.

Then an SSR will be perfect, you don't need a contactor, the SSR does the job on its own. This is almost an identical purpose for which I bought
my SSR. I wanted to turn my coolant pump (240VAC) on and off, and my BoB signals 24V up to 50mA.

The SRR will work with any DC control voltage from 4VDC to 32VDC and under 20mA, so your 12V 50mA signal will be fine.
It can switch anywhere from 24VAC to 240VAC at up to 15A, so it will switch your coolant pump on and off no trouble.

So you don't need a contactor or a relay...just an SSR.

Craig

[maxspongebob]

Hi,



Then an SSR will be perfect, you don't need a contactor, the SSR does the job on its own. This is almost an identical purpose for which I bought
my SSR. I wanted to turn my coolant pump (240VAC) on and off, and my BoB signals 24V up to 50mA.

The SRR will work with any DC control voltage from 4VDC to 32VDC and under 20mA, so your 12V 50mA signal will be fine.
It can switch anywhere from 24VAC to 240VAC at up to 15A, so it will switch your coolant pump on and off no trouble.

So you don't need a contactor or a relay...just an SSR.

Craig

Joe has it right here.
However you must be careful about where you use a SSR. Many of them don't turn OFF completely. The cheap one's have a leakage current that will still provide a voltage at the output. This should not be a problem when running a motor for a pump, but in some situations it can cause a problem.

[joeavaerage]

Hi,

However you must be careful about where you use a SSR. Many of them don't turn OFF completely.

That is quite correct, the unit I linked to has a max leakage current of 7mA, so its not too bad.....but I'd never trust it to isolate the circuit if I were working on it....no way!

Craig

[mactec54]

Joe has it right here.
However you must be careful about where you use a SSR. Many of them don't turn OFF completely. The cheap one's have a leakage current that will still provide a voltage at the output. This should not be a problem when running a motor for a pump, but in some situations it can cause a problem.

This only happens if you buy the cheap Chinese SSR's, using quality brand name SSR's and this does not happen.