[ausev] can I do this without blowing myself up...?

[Christopher Robison]

If current can be split between the two contacts simultaneously (i.e.
they throw together) then it sounds like this switch is DPST, not SPDT.
(SPDT would have a common connection, and then two contacts that are
connected interchangeably depending on the position of the switch.)

Also, you have to derate for current significantly for a DC-rated
application, if you're only given an AC rating. DC is harder to switch
than AC given that AC crosses through zero 120 times a second. Maybe
others can weigh in here but it sounds like this switch won't
necessarily be safe.

  --chris


On Sun, 2006-03-12 at 07:49 -0600, MLAB wrote:
> I am making a key switch for electric load-hauler, using a relay through 
> which all the battery power will pass on its way to the controller. 
> This will be a 36V system running 2x 500 watt motors, so I expect the 
> peak amp draw to be about 35 amps.
> 
> I have a big relay here (an Omron G7L-2A-TJ-CB), which is a single-pole 
> double throw model, so it has two sets of contact, each rated 25 amps 
> each.  (Granted, it says 25A 277VAC, but I figure it can handle 25A 
> 36VDC, or am I just cruising for bruising?)
> 
> Anyway, would it be safe to split the battery wire into two (full size) 
> wires and run the current through both sets of contacts?  These would be 
> simultaneously switched by the key switch.  Presumably, each contact 
> would carry max 18 amps, or half of battery current.
> 
> Is there something I am missing?  Or would this be a safe arrangement?
> 
>