Gallery, Projects and General > How do I??

High Voltage Switches

<< < (4/5) > >>

John Hill:
Darren, yes, slip is continuous in that it is always there in an asychronous induction motor in.  A typical two pole 50Hz motor would would assume would run at 1500RPM? But the name plate will show something like 1480RPM, the difference is slip.  Leastwise thats how I understand it.

There is prubably a transformer I  could have found for you but freight would have been a challenge! :coffee:  Of course if current was your only issue you could have used multiple trannies in parallel (?).  Being careful to observe phase of course!!!!   If you need 440V  I think you could use the secondary winding of an old isolation transformer in boost, if I recall correctly all transformers are insulation rated for 1Kv but you would still want to think about it before making the connection.

I cant even get my lathe (very much the same as Mr Bogs has over at Bandit's place) to start in the top ranges without tripping circuit breakers but it does spin up OK if I take the chuck off!  I could up the circuit capacity but I am tending towards some sort of clutch to get around this little problem,  I dont see 3 phase as attractive for that job.


I have tried a 3 phase motor on single phase using the fairly well advertised methods but with only modest success and not having a real need for it I never perservered.
 

Darren:
Had a quick look at Wiki....http://en.wikipedia.org/wiki/Electric_motor

Our Machine motors don't have slip as they are AC Synchronous, it's asynchronous that has slip.


AC Synchronous are in sync with the mains frequency, that's what controls their speed. (unlike DC motors where voltage controls speed)

With an AC Synchronous you can vary the voltage but the speed will not alter, though the power will. That's where these new fangled VFD's come into play as they vary the frequency to the motor to change the speed.

So, no slip in machine motors.

Darren:
John, what size breaker do you have on the lathe circuit and are you using a radial or ring circuit?

What is the power of the lathe motor and speed?

What is your domestic line voltage and what is stated on the lathe motor?

Questions, questions, questions..... :lol:

Darren:
Try a bigger start cap, that might do it.

It should give a boost for starting and if it's the type of motor I think it is the cap is cut out of circuit when the motor spins up.


But the previous quests are still relevant.... :thumbup:

Darren:
Ah, I think I know what you mean about slip now, (I was thinking of it being used in a different way) yes there has to be some for the motor to work.... otherwise the motor wouldn't chase itself round and round....... :lol: though some of the 1,500 - 1,480 speed loss is magnetic losses.
But this only aplies to single phase motors. The slip is generated by the run capacitor.

Older Iron cased motors have less losses than the new alloy cased motors and is partly why the older motors are more desirable then the new Chinese ones.

Three phase motors don't need slip as the phases do the chasing.


:thumbup:

Navigation

[0] Message Index

[#] Next page

[*] Previous page