Matronics Email Lists :: View topic - A 3 phase AC (Alternating Current) question

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

A 3 phase AC (Alternating Current) question

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

donjohnston

Joined: 13 Dec 2009
Posts: 231

Posted: Sun Feb 14, 2021 12:00 pm Post subject: A 3 phase AC (Alternating Current) question

Looking for some solutions on a project.



I have a lathe/mill combo.  I'm going to be upgrading it by replacing the motors and controlling them with VFD's.  Space is tight and it occurred to me that if I could use one VFD to control the motors (never at the same time) that would simplify the installation.  It would also save money since I would only need one VFD.  



But now the question is how to switch the VFD between the two motors? 



My first thought was a 3P2T switch.  But I have not been able to find one rated for 230VAC and 1HP.  It was suggested to use a contactor.  But then I would need a low voltage source for the contactor with a switch for that power source and now it's no longer simplifying things. 



Any ideas?

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

Ceengland

Joined: 11 Oct 2020
Posts: 391
Location: MS

Posted: Sun Feb 14, 2021 12:33 pm Post subject: A 3 phase AC (Alternating Current) question

On 2/14/2021 2:00 PM, donjohnston wrote:

 	  Quote: 	
		   



 Looking for some solutions on a project.



 I have a lathe/mill combo.  I'm going to be upgrading it by replacing the motors and controlling them with VFD's.  Space is tight and it occurred to me that if I could use one VFD to control the motors (never at the same time) that would simplify the installation.  It would also save money since I would only need one VFD. 



 But now the question is how to switch the VFD between the two motors?



 My first thought was a 3P2T switch.  But I have not been able to find one rated for 230VAC and 1HP.  It was suggested to use a contactor.  But then I would need a low voltage source for the contactor with a switch for that power source and now it's no longer simplifying things.



 Any ideas?

Contactors with 120VAC coils are used in thousands of devices.
	




1 HP should be easy to find; here's one rated at 30A per contact with a 

120V coil:

https://www.galco.com/buy/Deltrol-Controls/21011-84?source=googleshopping



The vendor's spec sheet says '30A  (at) 30V DC', so it should handle 30A AC 

with no problem at all.



I started by searching for '3pdt 30a 110v relay'



Charlie

-- 

This email has been checked for viruses by Avast antivirus software.

https://www.avast.com/antivirus

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

_________________
Charlie

donjohnston

Joined: 13 Dec 2009
Posts: 231

Posted: Sun Feb 14, 2021 2:08 pm Post subject: Re: A 3 phase AC (Alternating Current) question

Would I use one leg of the 230v supply to power the coil? 



(I haven't used a relay like this before)

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

user9253

Joined: 28 Mar 2008
Posts: 1922
Location: Riley TWP Michigan

Posted: Sun Feb 14, 2021 2:08 pm Post subject: Re: A 3 phase AC (Alternating Current) question

How about one of these switches: 

https://www.mouser.com/Electromechanical/Switches/Toggle-Switches/_/N-5g2jZ1yzvvqxZgjdhub?P=1z0z296Z1z0z20xZ1z0z2qcZ1z0yqrwZ1y8pmr4Z1y8ziurZ1y8ziusZ1z0z63x&Rl=5g2jZer5eZ1z0x8gwZ1z0x87nSGT&Ns=Current%20Rating|0

I assume that your VFD has an on-off switch controlling input power.

Turn the input power off before switching the output power from one motor to the other.

Then the switch will not even know that an inductive load is connected.

If you operate a switch with no load on it, then it will handle a lot more current 

without damage.  Even if a switch carries more current than its rating, it will 

not self destruct.  But its life might be shortened, for example from 100,000 cycles to 5,000 cycles.

A 3 phase, 240 volt motor will draw less than 4 amps according to this table:

https://twcontrols.com/lessons/motors-horsepower-and-amps-of-230vac-and-460vac-3-phase-60hz-electric-motors

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

_________________
Joe Gores

echristley(at)att.net
Guest

Posted: Sun Feb 14, 2021 4:10 pm Post subject: A 3 phase AC (Alternating Current) question

connect the switch to relays?  But, now you're talking six relays, so more complication.

                  

                                                                    On Sunday, February 14, 2021, 03:02:43 PM EST, donjohnston <don(at)velocity-xl.com> wrote:                 

                 



                 



                 --> AeroElectric-List message posted by: "donjohnston" <don(at)velocity-xl.com (don(at)velocity-xl.com)>



Looking for some solutions on a project.



I have a lathe/mill combo.  I'm going to be upgrading it by replacing the motors and controlling them with VFD's.  Space is tight and it occurred to me that if I could use one VFD to control the motors (never at the same time) that would simplify the installation.  It would also save money since I would only need one VFD.  



But now the question is how to switch the VFD between the two motors? 



My first thought was a 3P2T switch.  But I have not been able to find one rated for 230VAC and 1HP.  It was suggested to use a contactor.  But then I would need a low voltage source for the contactor with a switch for that power source and now it's no longer simplifying things. 



Any ideas?



Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=500688#500688



http://forums.matronics.comp;       - NEW MATRONICS LIST WIKI -



http://www.matronics.com/contribution====================

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

Display posts from previous:

	Matronics Email Lists Forum Index -> AeroElectric-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum