Silly question on a AC electric motor.

[dedndave]

well - you can get diodes that handle the voltage (PRV)
but, i would normally expect a full-wave bridge in that application (shown above in the drawing)
i dunno - maybe electricity in Oz is "split" like our 220 is
in which case, it could be a full-wave "center-tapped" rectifier


last choice is a half-wave rectifier - hardly see them in use because they are inefficient and harder to filter

[Bill Cravener]

. . . but its a mains 240 volt 50 cycle motor. . .

I've done a good bit of home and business wiring in my day Steve and there's nothing silly about a question when it involves 240 volts!

[dedndave]

that's fun stuff   :P
the few times i worked with 440, i used the lock-out/tag-out protocol, though   :U
that stuff will kill you dead

i am always surprised that countries like Australia and England have such high line voltages at the standard wall-plate
and 50 Hz - you can almost count the cycles as your teeth chatter - lol

[hutch--]

True confessions while wiring machinery. In OZ the industrial standard is 3 phase 415 volt AC and one of the machines I set up and used was a star - delta 10 hp induction motor that had a manual starter switch on it. After I first put it together it ran the wrong way so I went to the main switch for the factory busbar and pulled the lever down until it went clunk. Went back to the machine, took off the front cover for the switch block then touched the first terminal and WHACK, grabbed a live singe phase. After a few expletives I went back to the busbar switch and found out that it was a "clunk - CLUNK" two step switch. Been using neon tester screwdrivers ever since.  :bg

The factory has a 450 amp 3 phase 415 volt power supply that could run almost anything, had more than enough grunt to run the Lincoln SAE welder.

[vanjast]

Had a uninvited kick from 400 before, where some dickhead switched the mains back on, after I'd explicitly solidly taped the switches in the off position (standard procedure).
Half my right hand was numb for 30 minutes, and I ran around that hospital floor shouting and cursing for the idiot to own up.

Nope, I don't stand back when some moron tries to end my life.. I just let them have it.. idiots!!!!
:wink

[dedndave]

"taped in the off position" is not standard procedure   :bg

lock-out/tag-out protocol
http://www.northernsafety.com/news/Article/800569205/proper-lockout-tagout-protocols-protect-workers

[vanjast]

I know I know, but in darkest africa it is  :bg
There no other alternative as our dopey electricians and building engineers do not think to seperate the different power systems and throw them all into one DB panel.
So along comes another dopehead and starts throwing switches.. even ones that have tons of tape on them.... If you can figure this out you'll understand why africa is what it is...  :bg

The safety thing is not big here, but it's slowly creeping in with more modern companies... the ones that can survive the AA/BEE onslaught, or at least reject that form of racism. :tdown

[hutch--]

it depends on the switchboard but the safe way is to remove the fuse if its an old one or the circuit breaker if its a modern version. Then put a sign on the switchboard that you will KILL anyone who changes anything while you are working on the wiring. Then use a neon screwdriver indicator just in case and keep track of the switchboard.