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What type of switch do I need?

josh623

Plastic
Joined
Feb 26, 2016
Just need a little quick help here...

I have a KBAC 27D VFD on my grinder that I want to wire in a toggle switch that will allow me to switch from 1x speed to 2x speed on the fly. The way it works right now is there are three pins, the center pin basically connects to the pin on either side depending if I want 1x or 2 x speed.

When I called KB electronics he said I need a single pole, double throw, on/on switch. But there are so many options on McMaster that I'm not sure what specifically I need lol.

i-HtNtSSN-X2.jpg
 

josh623

Plastic
Joined
Feb 26, 2016
would this one work? Ideally it would lock to prevent accidental bumping when grinding.

I'm just not sure how the normally open/normally closed thing plays into it...

McMaster-Carr
 

josh623

Plastic
Joined
Feb 26, 2016
thanks for the input... I don't think I need 6 connections, I just have 3 wires. I need a switch that will basically let me pair either wire with the center wire (i.e. like the jumper does). So I figure that would be a 2-position on-on switch, correct?
 

crickets

Hot Rolled
Joined
Jul 3, 2021
thanks for the input... I don't think I need 6 connections, I just have 3 wires. I need a switch that will basically let me pair either wire with the center wire (i.e. like the jumper does). So I figure that would be a 2-position on-on switch, correct?

You don't have to use all 6. If the price/availability is better, 6 terminal one will work as well as 3 terminal one. The other thing is some of these switches are on-off-on and some are on-off. You probably want on-off type where 1 terminal is common, and either position shorts it to one of the other two.
 

Joe Gwinn

Stainless
Joined
Nov 22, 2009
Location
Boston, MA area
The VFD probably will not like switching this while in operation, and there will be smoke. How will this be prevented?

There may be a kosher way to do this on the fly. Consult user manual.
 

mjk

Titanium
Joined
Oct 20, 2005
Location
Wilmington DE USA
If your intent is to be able to switch between 1 and 2x speed without going in and moving a jumper I think adding an on-on switch will work.
But I agree about not switching while running, in fact a power down and possibly waiting may be necessary, depending on what components are in the switched circuit(capacitor?)
Once you have installed the switch, it works, and no smoke....make a label, no make a sign, that states "No one touch this switch while connected to power" or get a locking switch with a removable key
 

crickets

Hot Rolled
Joined
Jul 3, 2021
If there is any uncertainty about switching that thing under various states, it's better to reach out to the vendor and clarify with them.
 

madmachinst

Stainless
Joined
Jan 15, 2007
Location
Central FL
ramp it. I see teh VFD can be programmed for accel and decel with trim-pots. You just need a way to send an analog signal that corresponds to the RPM's you want. A Power Supply with 2 adjustable outputs and you have a DTSP switch with common going to VFD Neutral between PS and VFD directly. Messing with jumpers that were meant to be changed when VFD is off, while it is running is scary, and I take risks.
 

Rollerman

Cast Iron
Joined
Dec 18, 2004
Location
Waltham, MA
Carling makes poor quality switches. plated, maybe, brass contacts
Micro Switch makes a line of very high quality toggle switches. Silver contacts.
For switching motor power level voltage and current get a good switch.
 

BT Fabrication

Hot Rolled
Joined
Nov 3, 2019
any spdt(single pole, double throw) switch will work that closes the switch when moved to that side, lots in the automotive world at your local parts places for $10.
 

JST

Diamond
Joined
Jun 16, 2001
Location
St Louis
Automobile switches are not rated for 120 VAC.
Be careful!


The control contacts involved may or may not be on the "hot" part of the VFD. They are set and forget jumpers, so they might be without a problem, but probably they are on the I/O controller portion, which is most often isolated and at a safe voltage, The switches themselves are usually controlling low current 5V type signals

Check manual to be certain.
 








 
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