Re: [doc] Re: LED-lights flickering (Was: Re: Who can supply correct LEDs?)

[Martin Gutkowski <webmaster@xxxx>]

One thing we learnt ages ago is that the control stage is relatively
easy *in theory*, it's the power stage that's a headache especially when
something goes wrong (as you say) and you pop 4 fet packs worth £40
each! Our friend Si Harrison (King B) is now using 400A IGBT half-bridge
packs the size of a playing card- elegant but extremely expensive. Si is
the real genius behind our controllers. He works for a company supplying
and maintaining UPS systems and gets to rob secondhand silicon from old
systems being taken off line.

Draven has two 1200W S2 motors running at 24v - at stall (which in RW
happens all too often), they'll draw 250A. We've accidentally shorted
the supply cables (120A nom copper braid) and it popped like a fuse in
less than a second. Nasty.

BTW forgot to mention, our controllers weigh about 400g each - in RW,
it's all about weight too!

Martin

Nick Tomlinson wrote:

> That is true.
>
> I program the PLC logic controllers that control large plant drives/ automation for industry/ chemical plant/ water works/ nuclear fuel etc. Now these 2000 Amp motors are really big to drive pumps that are twice as big as me to supply mega-litres per minute. Top heavy stuff. They need thier own cable 4 inch thick. I'd hate to touch one of these bare cables and fry myself. Mind you getting the code wrong makes it expensive to put right !
>
> Makes the alternator on the delorean look even more puny !
>
> Nick.