At 03:29 PM 30/05/2010, Keith wrote:
>It's the controller - and yes it just starts ramping down the
>amperage to cool off, but that can happen at inopportune times. I
>added a fan today and that helps - I've got a Sevcon PMAC mounted on
>3/8 alum plate which in turn has a heatsink - all connected with
>that gooey thermal grease. I have a spot infrared sensor and it was
>showing about 200F on the face of the controller when it went into shutdown.
No fan before? that'd do it! You can have the biggest heatsink in the
world, but if the heat can't get off the heatsink, all it's doing is
buying time.
If you can put a hole or two through the heatsink, you can add a
thermal switch at the face of your plate to heatsink interface to
control the fan. That way the switch will see the heat pretty early.
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=140369787915&ssPageName=STRK:MEWAX:IT
is the ones that I'm putting onto the galvanic isolators that I've
been building for shore power - if the isolator starts to warm up,
sound the alarm because there is current happening where you don't want it.
>I think the 'sensor' on my motor overheating is molten copper being
>thrown about ;) (it's the Mars brushless)
100 amps continuous (says the specs, but that is with "free" cooling,
depends on wether the cooling air out can get away to be replaced by
fresh, cool air). 300 amps for 30 seconds or one minute depending on
whose selling the specs. Axial brushless spins the magnets, so I'd
think the dark and smelly smoke is the first sensor, then the
controller shutting down because the motor not doing as its' told
(naughty, naughty motor) before you'd have any thrown copper snot.
In my opinion, bad practice to run "things" at their limit for long,
if you see the need to run your motor at 100 amps for longer than a
few minutes at a time, I'd be adding extra cooling. I'm sure that
somewhen in the Electric Vehicle Discussion list, someone added an
external ducted blower to an Etek (Mars is a direct replacement for the Etek).
>And BTW...it wasn't all seriousness today - after I got some good
>work done I went out and had one of the best sails I've had in
>months! T-shirt & shorts in 15kts steady (a far cry from last weekend)
Aaahh.. Northern Hemisphere, coming into late spring. Here we've
mostly put away the summer toys... 40 degrees south in the path of
the Southern Ocean weather. Memorable day about 10 years ago (would
have been perfect for electric boating) mid-winters day, one of the
highland lakes, like a mirror. Got to get my trailer finished for my dinghy.
Regards
[Technik] James
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