Three phase relays.

[ajlelectronics]

I know nothing about them. A little searching suggests that most are safety devices that monitor the phases, but that isn't what I need.

Application is isolating my three phase compressor remotely by Alexa. I can supply a switched single phase or a switched low Voltage and I want that to control the three phase supply. What should I be looking for?

 

[Anguz]

3 pole contactor

 

[Onoff]

You just want a 3 phase relay that'll cope with your compressor. Select coil voltage to suit.

 

[Onoff]

Want me to have a look at what I've got here? I sort of collect them. Probably have something decently chunky. 230VAC coil OK?

 

[ajlelectronics]

Want me to have a look at what I've got here? I sort of collect them. Probably have something decently chunky. 230VAC coil OK?

Sounds good to me! All I have found so far is three phase input types. Ideally 240v in so that I can feed it straight from an Alexa switch.

 

[Onoff]

Sounds good to me! All I have found so far is three phase input types. Ideally 240v in so that I can feed it straight from an Alexa switch.

I'll go look in a bit.

 

[sako243]

Sounds good to me! All I have found so far is three phase input types. Ideally 240v in so that I can feed it straight from an Alexa switch.

I've got a few 3 phase 230V coil contactors lying about. Only used for some testing on a press brake, they ain't cheap though but if you wanted on. Think they were 32A at least.

 

[Martin-Sy]

What is the rating of the compressor motor?

 

[ajlelectronics]

What is the rating of the compressor motor?

4.5HP from memory.

 

[mtt.tr]

Why not just use a 24v coil contactor and a intermediate relay

 

[Onoff]

I've this if you want:

Just saw a 24V coil one in the garage too, think it was AC...

 

[ajlelectronics]

I've this if you want:

View attachment 414660

View attachment 414659

Just saw a 24V coil one in the garage too, think it was AC...

That looks ideal for my purposes. Paypal FF suit you?

 

[Onoff]

That looks ideal for my purposes. Paypal FF suit you?

Whatever. I'll chuck some mains on this later and make sure it pulls in and that I have continuity across all the contacts.

Is your address the same as on your business card? Still have it from when I had some fuel pipe off you.

 

[knighty]

Do you want to isolate it or turn it on/off?

 

[ajlelectronics]

Do you want to isolate it or turn it on/off?

The issue is that I often forget to turn it off at the isolator and so it starts up out of hours, which annoys next door. The idea is to add an Alexa switch to my "Alexa, turn off workshop" routine which will also prevent the compressor starting up.

 

[ajlelectronics]

Whatever. I'll chuck some mains on this later and make sure it pulls in and that I have continuity across all the contacts.

Is your address the same as on your business card? Still have it from when I had some fuel pipe off you.

Yes, nothing has changed address wise. Trying to be retired but it doesn't seem to have made any positive difference, quite the reverse with far too much to do!

 

[Onoff]

Trying to be retired

Me too, only 11 years to go!

 

[Agroshield]

The issue is that I often forget to turn it off at the isolator...

Kind of the opposite side of the coin to knighty: when you want to turn the compressor back on in the morning, consider if you want to have the contactor closing as the machine is trying to pull full start up current.

 

[knighty]

half decent contactor will full load start 4.5hp no problem

I was wondering if he intended to turn the compressor on/off with the contactor, which would bypass the unloader valve

might be better to just wire in a timer, then it'll do it every day for you and you don't need to worry about it?


got a photo of the wiring? is there's an electrics box or just the on/off button with built in pressure switch?

 

[Onoff]

One chunky contactor in the post this morning, every expense spared so 2nd class

I checked it on 230V, aok, continuity across all 3 poles etc. Comes in with a satisfying clunk!