Thread: cutout switches

A bit weedy? Is 16A on a single phase machine not enough for you? I would completely agree for a three phase machine where there is much higher inrush, hence the heavy contactor rated 20A+. I would be interested to see what actualy is inside one of these $100-150 boxes that justifies the cost. The switches activated by the buttons on the front of these dol boxes are not very different (rating) to what I have posted here.

I have come across a little trouble with dust getting into these switches but electrically you don't need much to drive a 2hp machine.

Happy to be proven wrong but I'd like to see it backed up...

A bit weedy... yep cheap moulded plastic, snap together construction and staked terminals.

Sorry its a cheap crappy piece of switch gear suitable only for light duty applications, like those little tile cutters, scroll saws and other bench top equipment......probably OK on a small drill press

wots in a dol starter that makes them so expensive.....proper industrial switch gear.

a full set of clamp type screw terminals, including earth connections

a proper fullsized contactor with multiple 500 volt rated contacts..contacts that can be cleaned if necessary.

configured for single phase provides complete isolation of the motor from the supply

Contacts that are rated for heavy motor starting.....my saw bench draws over 50 amps on start up and runs on a 20 amp circuit......its suposed to be 3Hp
My band saw is suposed to be 2 HP and came fitted with a 15 amp plug, I have not measured its peak start current but I expect it to be arround 30 to 40 amps

A fully servicable device

an adjustable overload device

the ability to connect external switches to activate start and stop function or for interlocks.

all that in a substantial IP rated case with proper and multiple cable entries.

the better and more expensive brands you can buy most components of the unit as spare parts

That is why that are called a starter, because there is more to them that a switch....they are a complete motor management system in a box.

are all those features used...well yess.
My band saw has interlocks on the doors, as is required under most OHS recommendations.

I have triggered the overload on the saw bench a couple of times when I have been a little ...um..ambitious.

I did have a motor blow up on the band saw before i replaced its starter with a real one.....it was replaced under waranty... but may have never blown if there was an overload in the original starter.

One of these days I will wire a toe bar kill switch on the saw bench..as it came there is a mushroom button stop switch on the left hand side of the machine so you dont have to "cross the blade" to stop the machine.

serioulsy..for anything with a decent sized motor....any stationary machine over 1hp, they are a realy good idea.

cheers

Soundman that's a good explanation. I do not argue that the you are paying for something that will do everything and last for the life of the machine.

Couple of points to note:
- On the smaller machine the motor itself often has thermal overload incorporated into it's starter circuit

- Additional stop switches or e switches are wired in series with the hold in coil, wether its industrial switch gear or these units, so choosing between the two will not limit this feature.

For my money, I'm just suggesting that the full starter boxes are not the only option.

As far as thermal overloads in motors...tru some do....a hell of a lot dont...some motors have a no resetable thermal fuse....blow that and your motor is shot.

As for the external switches.....have a good look at the switch pictured.....if you want external switches you have to specify the unit with the extra connector and that will probaly only be the hold up circuit it wont allow you a remote start.

An fulls sized DOL starter certainly is not the only option...but on any decent sized piece of stationary equipment they are by far the best option.

would I use one of those cheap items......yes I would...perhaps on drill press...they would be an ideal replacement for the cheap rockers or toggles that come supplied on most...they would also go well on smaller sanders..... but realy they are limited to smaller mostly bench top items.

another issue is that the switch pictured requires some sort of cavity so it can be flush mounted, or it would have to be mounted in a suitable box.

cheers

Good point about the remote start, I didn't think of that. Looking at the wiring diagram I'd say you're right. Not like just putting another "start" button in parallel.

Good discussion, hope others can learn from it like I have.

Well yeh it is....but those little switches dont give access to do so.

strat buttons in paralell, stop buttons and interlocks in series

cheers