Revolving door

[m sleem]

Is it applicable to supply a 3ph delta 220v ac motor by a single phase 220v?

Also, why we do need to go for a 3ph motor instead of 1ph particularly where the load is just 0.2 kw?

 

[tom baker]

A three phase motor requires 3 phase supply. Search for a you tube video on rotating magnetic field
The type of motor is a design choice but typically 3 hp and under are single phase

 

[m sleem]

A three phase motor requires 3 phase supply.

After a quick search on web, it can be thru either a phase converter or a variable frequency drive.

 

[winnie]

Correct. The motor requires 3 phase power.

At 200W an electronic VFD is a cheap way to create 3 phase power from a single phase supply.

 

[gar]

230429-0759 EDT

m sleem:

Ideally a three phase motor from fixed in space coils produces a constant amplitude rotating magnetic vector.

If you put a constant amplitude ( a DC magnet ) in that rotating field, then that magnet will lock on to the rotating field and rotate in space in sync with the rotating field. That is called a synchronous motor.

If you provide single phase power to a fixed coil, then you do not produce a rotating magnetic field. Rather you get a magnetic field that in only one direction varies from a zero to a high positive level in said direction, then reverses going to zero, continues its reverse, goes to a high negative value, reverses again going back to zero. Then the whole process repeats. Put a fix magnet in that field and it does not rotate, but just vibrates.

An induction motor is some what the same, but lacks synchronous operation. Rather it has slip and is never synchronous because there always at least some minimum load that produces at least a small amount of slip.

 

[drcampbell]

... why we do need to go for a 3ph motor instead of 1ph particularly where the load is just 0.2 kw?

There wasn't any need for a three-phase motor. It was just a design choice for simplicity, longevity and low maintenance. If the building is big enough to require a powered revolving door, it's reasonable to assume that three-phase power would be available, and using a three-phase motor means eliminating the starting winding, the start/run capacitor(s), and the centrifugal start/run switch.

I notice you're in "Cairo". Egypt, I presume? Some of the advice from the Americans here won't be applicable to your different conventions of power distribution.

 

[gar]

230429-1007 EDT

Another difference between single phase and three phase motors is torque ripple. Near 0 with three phase and substantial with single phase.

..

 

[kwired]

Correct. The motor requires 3 phase power.

At 200W an electronic VFD is a cheap way to create 3 phase power from a single phase supply.

If motor is only 200W, maybe even can be done with just a capacitor or two? Kind of depends how much starting torque may be needed.

 

[m sleem]

230429-0759 EDT

m sleem:

Ideally a three phase motor from fixed in space coils produces a constant amplitude rotating magnetic vector.

If you put a constant amplitude ( a DC magnet ) in that rotating field, then that magnet will lock on to the rotating field and rotate in space in sync with the rotating field. That is called a synchronous motor.

Would that mean the used motor is an AC Synchronous motor ?

 

[winnie]

Would that mean the used motor is an AC Synchronous motor ?

Unknown. @gar was giving a permanent magnet AC synchronous motor as an example of how the 3 phase stator produces a 'rotating field' which then interacts with a rotor.

The same field concept is used with induction motors and reluctance motors. We don't know what you actually have.

In fact, a possibility not considered is that this revolving door already has internal VFDs for speed control. Do you have any documentation?

 

[m sleem]

......

In fact, a possibility not considered is that this revolving door already has internal VFDs for speed control. Do you have any documentation?

You're right, frequency converter is mentioned with few hints for speed control, but wiring diagram does not indicate the inverter in details.

 

[winnie]

If the equipment has an internal VFD, then it may be capable internally of converting single phase to three phase for the motor. The correct VFD can do this easily.

Unfortunately the wrong VFD will simply not work, or will fry itself, if you supply single phase power.

This will all come down to the documentation or instructions from the manufacturer. What range of supply voltage, frequency, and phase count will the system accept.

The fact that there is a 3 phase motor internal to the system is irrelevant.

Jon

 

[m sleem]

If the equipment has an internal VFD, then it may be capable internally of converting single phase to three phase for the motor. The correct VFD can do this easily.

Unfortunately the wrong VFD will simply not work, or will fry itself, if you supply single phase power.

This will all come down to the documentation or instructions from the manufacturer. What range of supply voltage, frequency, and phase count will the system accept.

The fact that there is a 3 phase motor internal to the system is irrelevant.

Jon

Please have a look at the attachments similar to our revolving door.

 

[winnie]

Please have a look at the attachments similar to our revolving door.

That is the wiring diagram for a VFD being used to run a 3 phase induction motor using a single phase supply. It doesn't say anything about voltage or frequency limits, and the 0.2-2.2kW phrase suggests it is a general document, not for a specific apparatus.

You say "similar to our revolving door". What is the difference? Do you have the wiring diagram for your exact revolving door?

-Jon

 

[kwired]

That is the wiring diagram for a VFD being used to run a 3 phase induction motor using a single phase supply. It doesn't say anything about voltage or frequency limits, and the 0.2-2.2kW phrase suggests it is a general document, not for a specific apparatus.

You say "similar to our revolving door". What is the difference? Do you have the wiring diagram for your exact revolving door?

-Jon

Similar in that many VFD connection diagrams look nearly identical to that diagram regardless what the driven load is, so this sort of confirms that he has a VFD driven revolving door and that it likely intended to have single phase input and three phase output.