Transformer, Relay, Low Voltage - Electrical - DIY Chatroom Home Improvement Forum


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Display Modes
Old 12-21-2010, 01:29 PM   #1
Newbie
 
Join Date: Dec 2010
Location: Delaware
Posts: 5
Rewards Points: 10
Question

Transformer, Relay, Low Voltage


Hello everyone, I found this site through Google and thought you guys might be able to help me out.

For Christmas I am installing a VacPan in my fathers kitchen. A VacPan is an attachment that goes to a central vacuum system. I am trying to connect it up to a shop vac out in his garage. The VacPan has a low voltage foot switch that turns on the vacuum. Here is where the small problem comes in to play. (Stupid Low Voltage) but safety first right?

From my understanding I will need a 120VAC Transformer to 12VDC then a 12VDC Relay to control the 120VAC. I attached a diagram, I hope it uploaded. If this is correct my next problem is where do I find this stuff? Radio Shack now a days sucks, Home Depot has no clue, as does Loews. I just need to make sure I am buying the correct stuff and wiring it right.

Thanks everyone
Dave
Attached Thumbnails
Transformer, Relay, Low Voltage-schematicvac.jpg  

Advertisement


Last edited by Kermit911; 12-21-2010 at 01:52 PM.
Kermit911 is offline   Reply With Quote
Old 12-21-2010, 02:41 PM   #2
Electrical Contractor
 
jbfan's Avatar
 
Join Date: Jun 2004
Location: Newnan GA
Posts: 5,964
Rewards Points: 2,324
Default

Transformer, Relay, Low Voltage


A door bell transformer and an ice cube relay.
You may have to go to a supply house to get the relay.

Advertisement

__________________
Yes I am a Pirate, 200 years too late. "Jimmy Buffett"
jbfan is offline   Reply With Quote
Old 12-21-2010, 03:12 PM   #3
Newbie
 
Join Date: Dec 2010
Location: Delaware
Posts: 5
Rewards Points: 10
Default

Transformer, Relay, Low Voltage


Great idea for the transformer, thanks! Now it comes down to the relay.

Dave
Kermit911 is offline   Reply With Quote
Old 12-21-2010, 06:11 PM   #4
WDR
Member
 
Join Date: Aug 2010
Posts: 94
Rewards Points: 75
Default

Transformer, Relay, Low Voltage


There are a lot of companies online that have electrical components, I have had good luck with McMaster Carr.

Last edited by WDR; 12-21-2010 at 07:26 PM.
WDR is offline   Reply With Quote
Old 12-21-2010, 06:20 PM   #5
Member
 
joed's Avatar
 
Join Date: Mar 2005
Location: Welland, Ontario
Posts: 8,381
Rewards Points: 3,556
Blog Entries: 4
Default

Transformer, Relay, Low Voltage


A door bell transformer is only a transformer. You indicate DC voltage on your drawing. You need more than just a transformer to get DC.

Or you need an AC relay not a DC one.
__________________
Do not PM with questions that can be asked in a forum. I will not respond.
joed is offline   Reply With Quote
Old 12-21-2010, 07:46 PM   #6
Newbie
 
Join Date: Dec 2010
Location: Delaware
Posts: 5
Rewards Points: 10
Default

Transformer, Relay, Low Voltage


See... there in lies the problem. I know what I need (vaguely), I know I need a transformer to lower the voltage, and I know I need a relay that the lower voltage can switch to turn on the higher voltage. Now it is the specifics that I need help with. There are soooo many transformers and relays I'm not sure "exactly" what I need. Any ideas?

Do I need DC? No, but I belive DC is safer then AC correct?
Does the low voltage have to be 12V? No, it can also be 24V but the transformer and the relay have to match. So I don;t want to buy a transformer not knowing if the relay is going to work with it or not. Got to LOVE electricity, one little thing will change everything... then blow up.

Lets try this, will this work for what I am trying to do?
http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWAX:IT
I know it is 24V that's fine and I know it is probably AC current not DC which I am also fine with. As long as it works.


Thanks
Dave

Last edited by Kermit911; 12-21-2010 at 08:08 PM.
Kermit911 is offline   Reply With Quote
Old 12-21-2010, 08:10 PM   #7
Member
 
joed's Avatar
 
Join Date: Mar 2005
Location: Welland, Ontario
Posts: 8,381
Rewards Points: 3,556
Blog Entries: 4
Default

Transformer, Relay, Low Voltage


Here is one ready made for you.

http://www.pennstateind.com/store/LRMSET110.html




Keep everything AC and you will be fine. The contacts on the relay need to be motor rated. A vacuum is a significant load. A tiny isn't going to cut it.

Here is one example of a motor contactor.

__________________
Do not PM with questions that can be asked in a forum. I will not respond.
joed is offline   Reply With Quote
Old 12-21-2010, 08:21 PM   #8
WDR
Member
 
Join Date: Aug 2010
Posts: 94
Rewards Points: 75
Default

Transformer, Relay, Low Voltage


This relay and transformer should together. You would have to cut the plug off of the adapter cord and get a box to put the relay in.The relay has quik connect terminals, you can get the matching ones at a auto parts store or order them, you could also order a box for the relay

this is the transformer item # 70235K68

this the relay item # 7678K41

they are both from www.mcmaster.com
WDR is offline   Reply With Quote
Old 12-21-2010, 09:07 PM   #9
Newbie
 
Join Date: Dec 2010
Location: Delaware
Posts: 5
Rewards Points: 10
Default

Transformer, Relay, Low Voltage


You guys ROCK!!! I think I might like it here. Thanks for all the help everyone and all the suggestions.
Kermit911 is offline   Reply With Quote
Old 06-20-2013, 12:32 AM   #10
Newbie
 
Join Date: Jun 2013
Posts: 4
Rewards Points: 10
Default

Transformer, Relay, Low Voltage


Bringing this thread back from the dead. I'm doing the same project and wanted to verify some details.

What wattage should the transformer be rated? Is 80W high enough...at least it's higher than a doorbell transformer.

I also need some clarification to understand the schematic in this thread. Is this right?
1) 120V AC power comes from the breaker through the relay and into the outlet. The transformer also has a 120V AC feed from the breaker.
2) The shop vac is plugged into the outlet that's hot is interrupted by the relay.
3) The relay connects to the transformer and the vac pan accessory.

Looking at the drawing, I guess I'm confused as to where the power comes in and how the relay works...

Here are the parts I'm working with:
Solid Stare Relay (SSR) 25DA with heat sink
Small Shop Vac (1 HP, 6A)
120VAC to 12V DC 80 Watt Transformer

Can anyone help?!
dvanallen is offline   Reply With Quote
Old 06-20-2013, 11:12 AM   #11
Member
 
biggles's Avatar
 
Join Date: Jan 2008
Location: Long Island
Posts: 3,630
Rewards Points: 2,000
Default

Transformer, Relay, Low Voltage


what's with the 12VDC controlling the sequence......? just do it with 24VAC TR and 24VAC general purpose relay all is availible at local Grainger we're not talking Three Mile Island tranformers as shown.. here need to relax with low voltages....the VA rating on a TR is critical if you have a long control wire run out...or the contolling relay will buzz chatter or nothing with voltage on it at the coil

Last edited by biggles; 06-20-2013 at 11:15 AM.
biggles is offline   Reply With Quote
Old 06-20-2013, 01:58 PM   #12
Newbie
 
Join Date: Jun 2013
Posts: 4
Rewards Points: 10
Default

Transformer, Relay, Low Voltage


Thanks for the reply. So I've already bought those parts...It's good to know now that the transformer might be a bit oversized. My concern was that the 6A motor would stress a smaller one, and it wasn't that expensive anyway. I understand now that the transformer doesn't have to handle an inrush load from the motor -- it's only powering the relay, so it can be smaller . . .

My original Q was about how to wire it all together. I need some help translating the schematic into English! Can you help with that?

Last edited by dvanallen; 06-21-2013 at 11:39 AM. Reason: adding clarifications/paying it forward
dvanallen is offline   Reply With Quote
Old 06-20-2013, 02:14 PM   #13
Member
 
biggles's Avatar
 
Join Date: Jan 2008
Location: Long Island
Posts: 3,630
Rewards Points: 2,000
Default

Transformer, Relay, Low Voltage


on the control side (low voltage) wire the TR directly to the control relay coil...then break the yellow or red HOT off the TR with a switch.on the 115V motor side the relay has Common/Normally open/Normally closed contacts...you want N.O. ---I I--- and C.115v house feed "black" to relay C then N.O. to motor,other motor wire to "white" neutral from house.when the control powers the coil (close control switch) the relay will close the contacts on same relay and run the motor.that 6A rating is good but check the relay rating on the contacts should show max
biggles is offline   Reply With Quote
Old 06-20-2013, 04:08 PM   #14
Newbie
 
Join Date: Jun 2013
Posts: 4
Rewards Points: 10
Default

Transformer, Relay, Low Voltage


That makes sense. To confirm my understanding, is this right:
  • So in the diagram above, in the lower left corner (120V AC Plug w/ gnd), that is one of the two feeds coming from my my circuit breaker.
  • The other feed from the circuit breaker powers the transformer. If I feed the transformer according to the diagram, it addresses the black (hot) and white (neutral/ground) wires. I would just wire the bare (ground) wire to the 120VAC Outlet w/gnd box.
  • On the bottom middle of the diagram where it's labeled 120VAC Outlet w/gnd, that's the outlet that my Shop Vac is plugged into.
  • You mention breaking the yellow or red HOT off the TR with a switch -- that switch is the 12VDC Vac Pan accessory.

Is all of this correct? Thanks!

Quote:
Originally Posted by biggles View Post
on the control side (low voltage) wire the TR directly to the control relay coil...then break the yellow or red HOT off the TR with a switch.on the 115V motor side the relay has Common/Normally open/Normally closed contacts...you want N.O. ---I I--- and C.115v house feed "black" to relay C then N.O. to motor,other motor wire to "white" neutral from house.when the control powers the coil (close control switch) the relay will close the contacts on same relay and run the motor.that 6A rating is good but check the relay rating on the contacts should show max
dvanallen is offline   Reply With Quote
Old 06-20-2013, 04:50 PM   #15
Member
 
biggles's Avatar
 
Join Date: Jan 2008
Location: Long Island
Posts: 3,630
Rewards Points: 2,000
Default

Transformer, Relay, Low Voltage


the ground as label is really the white neutral on all 115VAC wiring 3-wires black/white/copper bare.the ground is raw copper from the CB panel to any place a wire nut is used to continue it thru the set up.the plug should be 3 prong...only need one 115VAC CB feed then that transformer can be tapped off the 115VAC plug before the relay,so when your unplugged (no 115VAC to the contacts of the relay) the TR is powered down .the white is considered the electrical ground insulated,and the raw copper is a mechanical ground...Vac Pan Ac is the low voltage ON/OFF raw copper grounding wire is connected to anything that can conduct electricity metal casing switchs..green screw is the landing point if seen anywhere.

Advertisement

biggles is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Wiring a Honeywell RA89A Relay shawnmd HVAC 7 10-21-2010 07:58 PM
Low Voltage Transformer Kevin321 Electrical 9 05-09-2010 11:39 AM
At what voltage is a 24v transformer considered too weak? philp HVAC 38 12-09-2009 12:05 PM
Central Ac transformer question Rschrei518 HVAC 4 10-20-2008 09:21 PM
Hard wired Low Voltage Transformer? VistaV Electrical 9 04-25-2008 11:04 AM




Top of Page | View New Posts