B
Bob Parker
oh yeah. I've got a bus discharge resistor I made up in the 90's when I
was a design engineer at PDL electronics, designing motor controllers.
Its a pair of 50R resistors in series, each rated for 11kW peak pulse
power, coated in heatshrink and attached to a pair of fluke DMM leads.
the tips are a lot shorter now than when I started
We used these in our production test area to discharge the DC bus of
drives that had been tested. a 400V 660A drive had 19.8mF at 800V (after
regeneration) so about 6.4kJ peak; from the AC line it was a mere 560V,
so only 3.1kJ. The 1MW drives were three 660As in parallel, so almost
20kJ in the DC bus.
occassionally the test tech would forget to turn the drive off before
discharging the bus. big problem, as you cant remove the leads, it just
arcs, shorts the DC bus and BANG goes $50,000 worth of product. And if
you left it there, the resistor went bang (and it typically pointed at
ones groin). So they'd scream, and someone would hit an E-stop and knock
out all the test bay power.
Fun stuff. One learns to be VERY careful.
Cheers
Terry
eeek! Better you than me!!
Bob
