Thread: Remote control on DC-7 dust extractor.

Originally Posted by DaveVman

But the one I just ordered this afternoon is a wee electromagnetic relay. That should cope shouldn't it?
How long do these 35+A start up currents typically carry on for on the DC-7? (without your Tim Allen motor mod).

About a second but it's more than enough to do long term damage on SS components with repeated restarting of something like DC.

I don't know what "Depending on how "bored out" the opening is,..." means.
"bored out"?
It's taking me so long to get the ducting figured out, I'm sure my DC-7 is bored out of it's skull but it will just have to harden up coz it's a machine.

Seriously though, I don't know what you mean. Right now, it's going to a 6m 150mm flex ribbed hose which snakes and curls its way over bench tops and connects to the 100mm port on the table saw. (No other flow into it except very leaky connections). I'll get you a photo if you like. Although that brilliant, shining, state of the art example of dust extraction engineering, will be upgraded gradually at my usual glacial pace.

Bored out means how free flowing the system is. eg 6" ducting all the way to machinery with the machine's port also bored out to 6". If its connected using 4" ducting to 4" ports then its the opposite ie choked down and start up currents wont be so great. Its a bit counter intuitive but that's how it works.

Not sure if it's the correct way but all I did was zip tie the on switch and plugged it into a remote control power plug, been working this way for years.

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Originally Posted by BobL

Bored out means how free flowing the system is. eg 6" ducting all the way to machinery with the machine's port also bored out to 6". If its connected using 4" ducting to 4" ports then its the opposite ie choked down and start up currents wont be so great. Its a bit counter intuitive but that's how it works.

Just off the top of my head - would it make sense to start the DE with all the blast gates closed to help protect your switchgear? You could then open up a blast gate once the impeller is up to speed.

Mine just had a cable with a plug running out of the motor box. It had been modified by the previous owners - a Men’s Shed.- so it automatically switched on when the thickie was fired up.

I have two remote switches exactly the same as dpb00. One switches the dusty and the other switches the Shop Vac. They have been doing their job for a long time now.

Originally Posted by Colin62

Just off the top of my head - would it make sense to start the DE with all the blast gates closed to help protect your switchgear? You could then open up a blast gate once the impeller is up to speed.

Unless it's a machine like a lathe or a belt sander that uses a wide open duct end (especially if it uses a BMH) and a very short length of ducting, the restrictivity of a machine and a few metres of ducting is usually enough to reduce the start up current to a manageable level.

Originally Posted by DaveVman

Yes. The Chinese write on them a certain current. Only by researching do you discover this is the peak current - NOT the max continuously operating current. They seem to think it is clever marketing to quote the highest possible number they can find in the spec sheets.
.

It's worse than that. Various tear downs show that the components in many of these units are only capable of safely handling a fraction of the rated power draw.

Originally Posted by RossM

It's worse than that. Various tear downs show that the components in many of these units are only capable of safely handling a fraction of the rated power draw.

Yet our beloved leaders are signing trade agreements which make the foreign manufacturers, importing into our countries immune from our laws and regulations.

@dpb00 Thanks for the photos. Is that a 10 Amp 2,200 Watt motor?
If it's a smaller motor then its a bit of a different story. The issue is about repetitively switching a 10 Amp motor on and off with components rated for 10 Amps.

Originally Posted by Lappa

Mine just had a cable with a plug running out of the motor box. It had been modified by the previous owners - a Men’s Shed.- so it automatically switched on when the thickie was fired up.

I have two remote switches exactly the same as dpb00. One switches the dusty and the other switches the Shop Vac. They have been doing their job for a long time now.

Does that a dusty have a 10 Amp 2,200 Watt motor?

Originally Posted by DaveVman

@dpb00 Thanks for the photos. Is that a 10 Amp 2,200 Watt motor?
If it's a smaller motor then its a bit of a different story. The issue is about repetitively switching a 10 Amp motor on and off with components rated for 10 Amps.

It's a carbatec model

https://www.carbatec.com.au/dust-con...ld-code-fm-300


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There are a lot more readers than writers on here.
Note standard warning about getting an electrician. etc.
Also I'm sure I'm not saying anything the guys on here don't already know but may I just remind the casual reader that in electrical engineering you want to always have a level of contingency. Just like in civil engineering. You never build a bridge at theoretical loadings. You always add an additional 50% over first principles because people's lives are at risk and just because "sh** happens" in the real world. Some concept in electrical engineering.
Like Bob's example above. I never imagined someone, outside of a factory, would stick their hand right inside a turned on machine. But what do you know - there is always someone. There have been plenty of industrial accidents like that.
I'm not discouraging anyone, or criticizing anyone - but just remember that you don't want to modify something electrical without considering this contingency approach. What could go wrong? Ask someone else to think about what could go wrong for that other perspective.
There is a cost/benefit calculation to be made but at least ponder that contingency question. Perhaps you decide the risk is acceptable, but at least you considered the risk and made an informed decision.
Most likely it will be fine while you are using it because you understand and respect it. The real risk I suspect is when someone else comes into your workshop.
I'm not trying to be a safety troll but just my friendly reminder, while we are on the topic.