Joined: 30 Sep 2006
Posts: 673
Location: Perth, Western Australia
Isolation switch
Does an SSR/car relay triggered by a small external switch meet the "battery isolator" rule? _________________ They say that he crossed the fine line, from insanity to genius.
Mon Nov 05, 2007 8:28 pm
Spockie-Tech Site Admin
Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia
I have not heard anyone ask that before, but my first thought is No.
SSR's are some form of silicon switches. One of the common failure modes for Fets is shorted (Fuses into a conductive blob inside), which means no reliable way of disabling power to the robot in the event of SSR failure.
If you can demonstrate the ability to remove a battery power lead from the robot in under 60 seconds as a "backup" disconnect method in the event of SSR failure, then it would be ok. _________________ Great minds discuss ideas. Average minds discuss events. Small minds discuss people
Mon Nov 05, 2007 9:30 pm
Fish_in_a_Barrel
Joined: 30 Sep 2006
Posts: 673
Location: Perth, Western Australia
I thought as much, just wondering. I guess the same would be true for a regular relay, in the case that a large current is drawn it would weld itself together. _________________ They say that he crossed the fine line, from insanity to genius.
Mon Nov 05, 2007 10:17 pm
Spockie-Tech Site Admin
Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia
A regular relay does have a form of mechanical disconnect where the contacts are physically moved apart (by spring pressure), unlike a SSR
but I still wouldnt reccomend it as a safety shutdown system since I have seen many of them weld closed.
Is there some reason you want to use a relay or SSR instead of a mechanical switch or disconnectable lead ? _________________ Great minds discuss ideas. Average minds discuss events. Small minds discuss people
Tue Nov 06, 2007 9:27 am
Fish_in_a_Barrel
Joined: 30 Sep 2006
Posts: 673
Location: Perth, Western Australia
No special reason, just the usual that my robot is low on space, and I'm low on cash.
Looks like now is the best time to impost a whyachi switch anyway, since the exchange rate is good. _________________ They say that he crossed the fine line, from insanity to genius.
Tue Nov 06, 2007 9:52 am
Spockie-Tech Site Admin
Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia
Hella 75amp switches from the local auto parts place are usually enough for most featherweights, or just use a 2 pin block connector that you can get to and unplug in under 60 seconds if cash is low.
If you use the hella switch, it might be a good idea to remove the big chrome knob to prevent accidental inertia/shock switch off's _________________ Great minds discuss ideas. Average minds discuss events. Small minds discuss people
60018 _________________ Satisfaction is proportional to effort and results.
Tue Nov 06, 2007 12:24 pm
Fish_in_a_Barrel
Joined: 30 Sep 2006
Posts: 673
Location: Perth, Western Australia
yeh, I have one of those sitting right in front of me. It just doesn't work in my design. _________________ They say that he crossed the fine line, from insanity to genius.
Tue Nov 06, 2007 12:36 pm
Rotwang Experienced Roboteer
Joined: 15 Jun 2004
Posts: 1589
Location: Vic
Now if you built from the inside out instead of the outside in you wouldn’t have these problems. _________________ Satisfaction is proportional to effort and results.
Tue Nov 06, 2007 12:58 pm
Valen Experienced Roboteer
Joined: 07 Jul 2004
Posts: 4436
Location: Sydney
there is always a "bolt switch"
get some micro switches, then use a bolt that slides past them to activate the switch.
Use the normally closed contacts to power the bot. slide the bolt in to "safe" it. extra points for using the same bolt to safe the wep. _________________ Mechanical engineers build weapons, civil engineers build targets
Tue Nov 06, 2007 3:44 pm
dyrodium Experienced Roboteer
Joined: 24 Aug 2004
Posts: 6476
Location: Sydney
I used that method for roadkill, along with the time where I was using a mono audio jack. It works fine. _________________ ( •_•)
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