Dust collector blast gate wiring with micro switches

[Rob in Oak Ridges [OP]]

I watched the following video of a gentleman who created a control box for his dust collector that has micro switches at each blast gate and when a gate is opened, the collector turns on and when closed, it turns off. The control box contains a Solid State relay SSR-40 DA and the control power is from an AC/DC power supply through micro switches. I'm probably not going to describe it well if I continue, so I'll get to my situation.

https://www.youtube.com/watch?v=iqJ1gggJfO4

In the video, his setup is for 120V to the DC, and in the comments he describes that for a 220v circuit, 2 relays can be used, one for each leg of the 220V. After watching the video his set up makes sense, and I've drawn up a diagram for my plans to wire it up for 220V.

He also comments that you can likely use a 2 pole relay, but I believe the pricing goes way up (using two SSD-40 DA relays is approx $30 for the pair vs well over $100 for a 2 pole relay.)

I'd appreciate anyone with experience in electrical work please have a look at my diagram and let me know if I'm on the right track or should I throw in the towel.

Also two initial questions

1. Re Thermal Protection. The motor doesn't have it separately and this option doesn't have it built in. Should I consider that here.?
2. If I use two separate relays as I've shown, if one relay fails, and the other is still good, and the system tries to start up, is there any danger there?

Thanks to any and all feedback - especially the constructive kind.

[Glen Black]

Cool ideal, as to your questions #1, why? if the motors don't have it, don't complicate the issue by trying to add it, not needed on small motors. #2 My thoughts are which is cheaper a double pole relay or a replacement Dust collector motor if something goes wrong? For the small price difference go Double pole, I am not saying that a double pole will not fail with one leg good and one bad, but the chances are really really really low.

Also if you use a four wire cable (2 x Hots, Ground, and a Neutral from the panel) so (Red, Black, White, Green) then you don't need a separate 120 line for the 24Vdc as you can pull 120Vac between a Hot and Neutral, or use a 24VDC Industrial supply (Cost more ie Phoenix) but you can put either 120 or 220 into it and 24Vdc comes out. The cheaper solution is the 4-wire solution and plug, they are a usually a twist lock, or sometimes called a generator plug. I have one setup to provide 220 for the table saw and 120 for the attached router table in one cord.

Glen

[DGB_WAT]

Rob,
I didn’t study your wiring diagram so don’t have feedback on that. My comment is about turning on and off the collector as frequently as you open and close blast gates. My understanding is that it is hard on the motor each time the DC is started because it is starting under load. For this reason, I try to limit the number of times I switch the DC off and then back on. As well, assuming your DC is doing a good job capturing fine dust, it will help to clean your shop air if you leave it running between machining operations.


David

[Rob in Oak Ridges [OP]]

Thank you both for your feedback Glen and David.
Glen, sorry to put you on the spot but overall, is the wiring in the diagram okay the way it is, from your perspective?, again not knowing your experience. I’ll definitely consider a 2pole relay. I appreciate the thought of the 4-wire cable, but it’s very easy for me to get a separate 120v line into this.

David, I agree it could be tough on the motor, but you haven’t seen the way I work (hahaha). I definitely don’t work fast enough to be jumping from machine to machine. Many use a remote to power their DC but this way makes sense to me, to know that (If the DC is off) all gates are closed, and the only one that will be open when I start an operation is the gate at the machine I’m using.

[Rod Sheridan]

Hi Rob, have you purchased the solid state relays?

I would use a 2 pole contractor with a 24 volt AC coil for the control.

I’ll mail you a contractor if you wish......Rod

[Todd]

Rod, you beat me to it, was thinking the same thing except i would add a 240/24V transformer and a couple of fuses inline with the transformer primaries then no need for the 120V cct

[billh]

If one SSR failed in the "on" position then the motor would start/stop as per the second SSR. If one SSR failed on the "off" position then the motor would not run when the other SSR was turned on. No different than if one pole of a contactor should fail.

Ideally, snubber circuits would be used with the SSRs, they probably should be used on contactor contacts too but often aren't.

If you stick with the SSRs you should be able to find a 120-240VAC input (runs on either) power supply for 5V, 12VDC output and eliminate the 120V line. The 5 and 12V voltages are common ones for chargers or computer equipment.

Going with a 240/24V transformer and a 24VAC contactor coils is probably the easiest.

billh

[Rob in Oak Ridges [OP]]

Hi Rob, have you purchased the solid state relays?

I would use a 2 pole contractor with a 24 volt AC coil for the control.

I’ll mail you a contractor if you wish......Rod

That’s a very generous offer Rod. No I haven’t purchased anything yet, and I do like the idea of a contactor vs separate relays. I’m sure I can find what I need near me, but failing that I might take you up on this.

[matt.mackinnon]

If you are ever down in Oakville, I have a relay from a 5hp Clearvue DC that you can have. I know I will never use it. I will go search it out in the shop for a photo and the specs.

Nope: sorry, can't find it right now. I might have given it away last year. I will keep an eye out though

[Rob in Oak Ridges [OP]]

The generosity in this group is incredible. Thank you Matt but don't go to too much trouble. I'll let you know if I would want to get it from you.
I am waiting for my father in law to get back in town to see if he has a suitable contactor and other pieces. He's a retired electrician and I'm sure can help me. He's been away for a while now, hence why I'm trying to learn alot of this on my own (with the help of everyone here).

[Rod Sheridan]

That’s a very generous offer Rod. No I haven’t purchased anything yet, and I do like the idea of a contactor vs separate relays. I’m sure I can find what I need near me, but failing that I might take you up on this.

You're welcome to a contactor and a transformer if you pay shipping. I can mail it out this weekend once I'm back in Toronto

I've attached a sketch for you.....Rod.

[Rob in Oak Ridges [OP]]

Hi Rod Sheridan

Thank you for the diagram. That makes alot of sense to me. And if I understand the Switch you've drawn, this is a Manual/Off/Auto Selector Switch so that I can select (at the panel) to have it run constantly (manual) or Auto (by the micro switches) or Off. I do like the idea of 'off' that way it can't start up over night if one of the switches fails.

Two questions and sorry to keep dragging this out.
I actually have a salvaged a Magnetic Starter rated for 3HP @230V so that should solve my need for a contactor. I will just need to get a 24V coil.
Question 1) it has an auxiliary switch on the side. But since I am planning to use the Control system in your drawing, I can just bypass that aux switch and connect directly into the 24V coil as you've drawn in the circled M...correct? (24v pos. to A1 and 24v neg. to A2)

Question 2) The 120V to 24V transformer. Does this need to be anything special. Do I need to know the specific ratings (VA's or anything like that) or is it a pretty straight forward transformer?

Hopefully my questions are making sense and if anyone else has any input I'm all ears!

Thanks
Rob

[Bryan @ Woodstock]

back in 85 I had a 3 hp 4 bag Grizzly DC and could turn it on and off at each homemade gate made from wood scraps. Relay was a used A/C contactor 240v/24v. An old knife switchbox became the housing for the relay, with the receptacle box/240V plug beneath via short conduit. 24 volt transformer off an old furnace. Magnetic burglar alarm switches screwed to the wood blast gates, normally open type would trip the relay. Used parts came from a local electrical contractor, even the alarm switches. I told the electrician my idea and he rounded up some used parts and how to hook it up. Used it for 20 years till I got my 3 hp Gorilla DC.

[Rod Sheridan]

Hi Rod Sheridan

Thank you for the diagram. That makes alot of sense to me. And if I understand the Switch you've drawn, this is a Manual/Off/Auto Selector Switch so that I can select (at the panel) to have it run constantly (manual) or Auto (by the micro switches) or Off. I do like the idea of 'off' that way it can't start up over night if one of the switches fails.

Two questions and sorry to keep dragging this out.
I actually have a salvaged a Magnetic Starter rated for 3HP @230V so that should solve my need for a contactor. I will just need to get a 24V coil.
Question 1) it has an auxiliary switch on the side. But since I am planning to use the Control system in your drawing, I can just bypass that aux switch and connect directly into the 24V coil as you've drawn in the circled M...correct? (24v pos. to A1 and 24v neg. to A2)

Question 2) The 120V to 24V transformer. Does this need to be anything special. Do I need to know the specific ratings (VA's or anything like that) or is it a pretty straight forward transformer?

Hopefully my questions are making sense and if anyone else has any input I'm all ears!

Thanks
Rob

Yes you could buy a coil however if you wait until Friday I'll mail you a new contactor and transformer free of charge.

Always happy to have someone help clean out my garage......Rod.

[Rob in Oak Ridges [OP]]

Yes you could buy a coil however if you wait until Friday I'll mail you a new contactor and transformer free of charge.

Always happy to have someone help clean out my garage......Rod.

Thanks Rod. I’ll send you a pm.