Single phase operation of asyncronous motor/generator
Single phase operation of asyncronous motor/generator
(OP)
I need to know if it makes sense to operate, at least during a small amount of time, a three phase asyncronous generator rated 5.5 kW, with a single phase supply.
The steinmetz connection doesnt make sense since the capacitor is too big n' expensive.
The olny think I worry is if I could run two phases for a short period with a reduced power output, namely 3.2kW, without fearing machine damage.
I read of the pulsating 100Hz torque of the single phase operation, but I can't find how big it is.
The max torque is reduced till 50%, but I think the power reduction will be ok.
Any improvements like conectin the other phases in a -180ยบ alternating voltage, I can't find any connection like this or studies saying if better or worse.
Can anyone help me?
Thanx for your comments anyway.
The steinmetz connection doesnt make sense since the capacitor is too big n' expensive.
The olny think I worry is if I could run two phases for a short period with a reduced power output, namely 3.2kW, without fearing machine damage.
I read of the pulsating 100Hz torque of the single phase operation, but I can't find how big it is.
The max torque is reduced till 50%, but I think the power reduction will be ok.
Any improvements like conectin the other phases in a -180ยบ alternating voltage, I can't find any connection like this or studies saying if better or worse.
Can anyone help me?
Thanx for your comments anyway.





RE: Single phase operation of asyncronous motor/generator
The KVA rating of the machine will be 2/3 of the three phase rating.
Caution, the full kilowatt output of the prime mover will still be available.
Typical ratings:
Set #1, Three phase, KVA 60, KW 48, PF 0.8
Will become, Single phase, KVA 40, KW 40, PF 1.0
Set #2 Three phase KVA 5.5, KW 5.5, PF 1.0
Will become Single phase KVA 3.7, KW 3.7, PF 1.0
The prime mover will still be able to force the original KW into the machine if it is overloaded. You must ensure that you have the machine protected for the new ratings as you will no longer have the backup protection of motor stalling in the event of overloads.
In you are unable to generate the voltages you need with a delta or double delta machine, use the zig-zag connection. This will also result in equal currents through the windings, but at different phase angles to the voltages.
If you need help with the connections, we will need some more information concerning your machine.
How many wires? (3, 6, 10, 12) Rated voltages, needed voltages?
Bill
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"Why not the best?"
Jimmy Carter