Looking for a 240V/100A relay ...

[electron]

I'd like to control a dedicated circuit which is powered by a dual pole breaker (standard 240V), and should be able to switch up to 100A.  While there are plenty of hits when checking search engines, I'd like to know if there is a 'popular' choice out there when it comes to this type of relays.
 
It would probably be wall mounted in my garage, and safety is extremely important.

 

[Scrambled]

E. look for a electrical contactor. They are made to handle 100 amps or more.


Steve

 

[electron]

Wow, unless I'm missing something, these devices are a lot more expensive than I thought.  I guess I might have to skip automating this part.
 
I do appreciate the response tho, as it pointed me in the right direction!

 

[BraveSirRobbin]

What are you switching?  Motor?  An 'inductive' load?  This would influence the type of contactor.
 
Here is an example of a Square-D (excellent brand) type, though only 90 amp rated (not sure exactly how this one is controlled, or if you have to buy an aux board for it, just a quick search to show a typical type).  Usually they have 'latching' coils so you typically pulse the latch coil with a control voltage to engage the contactor, then pulse the unlatch coil to disengage.  Some even have a contact indicator that will 'throw' in relation to the main contacts so you can pass a small control voltage to verify the main's positions (via a digital input on your I/O hardware).
 
I'm not a 'power' expert, but I could look into this some more if needed.

 

[fcwilt]

Yes a good one is going to be expensive. Transfer switches used with backup generators use big contactors and they can be quite impressive when activated, lots of light and sound.
 
To handle heavy loads and avoid problems with contact burning they even make mercury based units where a pool of mercury is one side of the contact and a metal rod is lowered into the mercury to close the circuit. These are fun.

 

[N49atv]

You need a contactor. It won't be cheap. As far as latching contacts, I haven't ran into any in years. Most you just use control wiring to hold the power on if you only want to pulse to is. This would require 2 outputs, where as maintained only needs 1 output.

You want a 240V, 100A, 2 pole contactor, with whatever Volt coil your control is (IE, 12V, 24V, 120V, 240V). I'd suggest 240V if your coil control relay will handle the voltage, if your not running straight off a HA output. That way you can just steal control power off the line lugs, and run through a control relay.

I could draw you a control schematic if needed, pretty basic.

 

[IndyMike]

The Square D contactor that BSR linked to is a NEMA size 30.  Excellent industrial quality contactor.
 
There are also "Definite Purpose Contactors" that can be had for a fraction of the NEMA price.  These come with limitations as described here http://www.eaton.com/ecm/idcplg?IdcService=GET_FILE&allowInterrupt=1&RevisionSelectionMethod=LatestReleased&noSaveAs=0&Rendition=Primary&dDocName=AP03501002E
 
If you understand your load and duty cycle you should be able to pick a contactor that will outlast the load. 
 
Do not try to use a contactor or relay device when using a mixed (inductive, resistive, capacitive) load unless you have over voltage protection. 

 

[apostolakisl]

This is an automatic transfer switch that is designed for generators but I see no reason why you can't use it to switch between no connection/utility instead of generator/utility.
 
http://www.homedepot.com/p/t/202060601?productId=202060601&storeId=10051&langId=-1&catalogId=10053&MERCH=REC-_-product-4-_-202851464-_-202060601-_-N#specifications
 
It is quite a bit cheaper than the above listed option.  Not sure if it will work for your application.  It looks it literally just physically turns a regular 125amp circuit breaker on/off.

 

[electron]

The plan is to control a car charging station, which really doesn't do much but supply 30A@240V to the car.  I wanted 100A in order to future proof the circuit, but I could go as low as 50A as that's the value I'm probably going to stick with for now.  I basically want to control the charging schedule, disconnect the charging station in case of bad weather, or just turn it off whenever the car isn't in the garage to avoid wasting any power.

 

[fcwilt]

How much power could it draw if it's not charging the car? I would think in comparison to the amount used to charge the car any standby current would be next to nothing.
 
Wall outlets don't draw power when nothing is plugged in.

 

[az1324]

http://www.kickstarter.com/projects/1076207974/emw-juicebox-an-open-source-level-2-ev-charging-st

 

[N49atv]

In that eaton PDF posted you would want a C25BNB240_B

That's a 40A, 2 pole contactor, with 208-240v coil. This will allow you to run 2 wires from your automation panel right next to the contactor, and allow you to mount the control relay next to it. Keeping AC circuitry separate from your automation.



You could then add an auxiliary contact to the side for a run status, or another relay off the T1/T2 terminals to let you know there is power to the charger, and that the breaker hasn't tripped. As I'm sure you don't want to hack into the load side of the car charger to get a status. Run either set of dry contacts (off aux contacts or relay) back to an input on your automation, if your output is on, and your status doesn't flag high, you can alert there is an issue.

Obviously a status from the charger output is better. I'd recommend fusing the L1 and L2 control wires, with a 500mA or 1A fuse on each wire.

 

[electron]

N49atv, thanks for the info.  That contactor is pretty affordable (will have to check if they have a 50A version).  What kind of enclosures do these usually get mounted in?
 
 

http://www.kickstarter.com/projects/1076207974/emw-juicebox-an-open-source-level-2-ev-charging-st

Yep, am aware of it, but with cables etc, it's not that cheap, plus I already purchased a top of the line unit before I spotted this one.  Very interesting project for sure.
 

How much power could it draw if it's not charging the car? I would think in comparison to the amount used to charge the car any standby current would be next to nothing.
 
Wall outlets don't draw power when nothing is plugged in.

Standby power isn't much (~6W), but too high considering it doesn't do anything but provide power (no conversion going on).  I'm more interested in isolated it from the grid in case of brownouts etc.

 

[az1324]

Yep, am aware of it, but with cables etc, it's not that cheap, plus I already purchased a top of the line unit before I spotted this one.  Very interesting project for sure.

I would consider selling it. A J1772 supply is just a contactor anyway with some minor electronics to communicate with the pilot protocol, right? So you are just putting a contactor in front of a contactor. Yes you would be protecting the other minor electronics, but they should be as resistant to failures as any other electronics that is powered by line voltage. The advantages of having live charge/consumption data, scheduling, control, etc. through remote (web/app) and open codebase/API is vastly preferable.

http://www.superbreakers.net/8910dpa93v02.html

https://code.google.com/p/open-evse/

 

[N49atv]

A contactor is usually mounted in a junction box. I normally use fiberglass JBs, but those are pricy. I'm in Canada so as far as steel enclosures I use Dandy, Ace, and Vancouver electric. Though you can look at Hoffman and Hammond. I didn't notice specs on size but id say an 8x10x6 (wxhxd)is probably large enough. Just give yourself a few inches on each end to form the wire into the terminals.