Dahlander motor rotary cam switch- off between speeds or not?

tomjelly · Sep 25, 2019

I can get switches configured 1-0-2 or 0-1-2 to control my 2 speed single winding (dahlander?) motor, I see both types. Does the power need to be off to change between speeds or no? I was ready to buy this switch:
Dahlander Pole Changing Motor Switch|2 Speed|20A|10HP: P0200014R which I would wire like this:

that turns off between speeds which I prefer so I can start at either speed rather than stepping thru the speeds (this is for a drill press), but now I see some others that switch directly from low to high speed without stopping. Is one type preferred?

Hopefuldave · Sep 25, 2019

As long as the switch is break-before-make you'll have a disconnect between speed selections - this is probably a Good Idea.
My Holbrook has a 3-speed motor (two from a Dahlander winding, one from a separate winding all its own) but the speed switching is by a huge Frankenstein switch operated by a long lever - the lever has to be moved out of detent to change speed, which operates a microswitch and drops out the main power contactor feeding the Frankenstein switch, they obviously thought it worth the effort to de-energise the contacts while speed switching.

Frankenstein switch being added to new electrical panel...

Dave H. (the other one)

tomjelly · Sep 25, 2019

igor, release the kites!
I'm going with the 1-0-2 configuration. I can't be sure the switches are break before make with the 0-1-2

9100 · Sep 28, 2019

I had a mill with a Dahlander motor. The high/low switch had a center off so I got in the habit of leaving the on/off switch on and switching high or low as desired. That burned up the high/low switch with its many little contacts. Because the switch was mounted in a pocket in a casting, I couldn't use a bigger one and installed the largest one that would fit. When I sold the mill, I warned the buyer to always switch speeds with the power off. He promptly burned up the new switch and had an electrician install one in a separate box. The moral to the tale is yes, switching with the power on works fine, but make sure the switch is up to the task.

Bill

tomjelly · Sep 28, 2019

this one is way oversize so I think it will be OK

jim rozen · Sep 29, 2019

The hardinge contactors for their dahlander motors seem to work just fine switching the hi/low
stick to start, stop, or go right from one speed to the other. Granted these are at most 3/4 hp motors.

The contacts in even their oldest switches are exactly the same in the hi/lo box as the fwd/off/rev box.

And abosolutely the same in the split bed lathes.

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Dahlander motor rotary cam switch- off between speeds or not?

tomjelly

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tomjelly

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9100

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tomjelly

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jim rozen

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