Interlock 5 Amps at 50VDC 1

[mcgyvr]

Have an application that needs to interrupt a 5A (maybe 7A) load at 50VDC when a door is opened and reconnect when the door is closed. Cost is a large concern..need around a $5 solution. Have looked into a simple pushbutton/relay but they don't seem to be available past a 28VDC rating for any decent load. I'm looking for any other suggestions on a possible solution.
Thanks

 

[ijl]

Magnet and a reed relay?

 

[mcgyvr]

A reed relay for 5-7 Amps? Doubt I'll find that too.

 

[ScottyUK]

You will struggle to find much in the electromechanical world which will interrupt that kind of current at 50V with a single break for $5, but could you use a multipole relay with multiple breaks in series? Three or four series breaks would be adequate - this technique is used to extend the voltage rating of circuit breakers in DC service.

Or... what might be the simple way: big MOSFET?


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If we learn from our mistakes I'm getting a great education!

 

[mcgyvr]

I have started looking into a Mosfet solution already after looking at solid state relays,etc... That might be the only option.

As for the multiple relay breaks... This final product that incorporates this interlock scheme needs to go through UL safety testing.. But I believe this type of operation would also require additional testing focused on the relays and standards that relays are required to be compliant with. That is NOT a road we want to travel. While I'm sure it's done, I don't believe it's something that UL will just okay.

Right now I've convinced them for the prototypes that a standard push pull breaker be used in place of the switch. The tech would still have to pull the handle to disconnect the load but the door would operate the breaker to the ON position when the door is closed to prevent him from leaving with the load still disconnected and having to return. Good thing is those breakers fit into my $5 solution.

 

[benta]

How about a classical microswitch:

http://sensing.honeywell.com/index.cfm/ci_id/154253/la_id/1.htm

They are rated up to 25 A and have the positive "click-action" that you probably look for.

Benta.

 

[mcgyvr]

Typical (classic) microswitches might carry a 25 Amp rating at 250VAC but are heavily derated to like 1/2 Amp at 125 VDC.

Just seems there is nothing out there to fill the gap between a relay/switch and then going to a contactor.

 

[benta]

The Honeywell "MT" series of microswitcher are rated 10 A at 125 VAC/VDC. Did you follow my link?

Benta.

 

[mcgyvr]

benta,
I did follow your link (and a quick search did not turn up that one so thanks).
That switch will work..BUT
Have you priced that switch series...$62 to 83 USD at digikey.com... Granted digikey prices are high (roughly double what you would really pay)...That will not meet my pricing requirement of $5 USD.
Closest so far though...

 

[benta]

Sorry, did not check prices, but perhaps if you call a real Honeywell distributor it'll look better.
Could also be that Omron has something like it.

Regards,

Benta.