What do I need to know to calculate size of single phase motor?

[pgrbff]

About 20 years ago I bought an old table saw from a local school. I only had single phase at the time so I changed the motor and switchgear as it was 450V. I'm thinking of buying a 3 phase 50s bandsaw and have the same problem, but I can't remember how to work out the size of the replacement single phase motor. Are there likely to be any other problems?

 

[Andy-1960]

I would have thought the easiest way round the issue is to match the new motor to the one you take off. I.E the same h.p / kw rating and the same speed as the three phase one you take off

 

[Strima]

Why not use a VFD and keep the three phase motor?

 

[pc1966]

Interesting idea, I guess these days a VFD is probably cheaper than a new motor? Also you probably get soft-start and the speed control might prove useful.

 

[pgrbff]

Why not use a VFD and keep the three phase motor?

I am/was assuming changing the motor will be the most economical route at the moment.

 

[pgrbff]

I would have thought the easiest way round the issue is to match the new motor to the one you take off. I.E the same h.p / kw rating and the same speed as the three phase one you take off

This is all the info I have.

 

[Strima]

I am/was assuming changing the motor will be the most economical route at the moment.

VFDs are dirt cheap and will save the hassle of trying to find the right frame to fit your machine.

 

[SheffSimon]

This is all the info I have.

Can't read that, but how old is the motor? A VFD will put a lot more stress on the motor windings and an old motor with old insulation will not like it.

Note also that a VFD running from a single phase supply provides 230VAC 3 phase not 415, at 50Hz. Which is fine if your motor is wound and can be connected accordingly.

Edit...can read it now....you can connect in delta 250V so the VFD voltage level should work. I would be concerned about the winding insulation with VFD operation.

 

[pgrbff]

Can't read that, but how old is the motor? A VFD will put a lot more stress on the motor windings and an old motor with old insulation will not like it.

Note also that a VFD running from a single phase supply provides 230VAC 3 phase not 415, at 50Hz. Which is fine if your motor is wound and can be connected accordingly.

Edit...can read it now....you can connect in delta 250V so the VFD voltage level should work. I would be concerned about the winding insulation with VFD operation.From what I'm told the machine is 50s or 60's.

From what I have been told the machine could be 50's or 60's. Is it possible to estimate the HP or KW from the info on that plate?

 

[telectrix]

it's round about 1kW.