Single-Phase motor and electricity abroad

[EngRepair]

I was reading somewhere about a specific issue relating to the application of single-phase motors in certain electricity distribution networks.
It is about the single-phase, capacitor-run motor which is designed for 230 V, 60 Hz. Connection to phase voltage ( L1 and N ie. phase and neutral). Network is 3 x 400 V, 60 Hz with neutral.

I wonder whether such a motor can work on the network 3 x 230 V, 60 Hz if it is connected to two phases (line-to-line voltage, L1 and L2)? The voltage will be the same.

 

[waross]

Yes it will work.
Many 60 Hz motors are rated at 230 Volts (or a multiple of 115 Volts) and are intended for use on 240 Volt circuits (or multiples of 120 Volts).
If your 230/400 Volt system is prone to low voltage and if the motor overheats, you may consider an auto transformer to boost the 230 Volts up closer to 240 volts.
If the motor is sized exactly for the load, it may get a little hot but many motors are somewhat oversized for their loads, and should work well on rated voltage.
The reason for the different voltage standards is to allow for line loss. Often a 240 Volt service will lose some voltage due to line loss and the actual voltage at the motor may be 230 Volts even though the voltage back at the distribution transformer is 240 Volts.
If your system is delivering a solid 230 volts to the motor great, however you may find that with line losses, the voltage at the motor when it is loaded is lower than 230 Volts.

Bill
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"Why not the best?"
Jimmy Carter

 

[EngRepair]

An issue could be related to angle between the two supply lines, rather then to value of voltage, I think.

 

[Skogsgurra]

No angle between one phase. The motor/capacitor only sees one voltage system, hence no phase angle to bother about.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[waross]

Further to Gunnar's post;
Consider the case of two synchronous motors running on the same supply derived from a line to neutral connection. Observe them with a stroboscope and note the angular positions of the the shafts.
Now change the supply so that one motor is still line to neutral and the other is connected line to line. Observation with a stroboscope will show that the angular position of the second motor has shifted a multiple of 30 degrees relative to the angular position of the first motor.
Are you using two synchronous motors and will this be important to your application?
If the motors are induction motors, then the slip frequency will render the relative shaft positions indeterminate, unimportant and changeable.


Bill
--------------------
"Why not the best?"
Jimmy Carter