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Unknown motor connection

Unknown motor connection

Unknown motor connection

(OP)
I have a theoretical question.
If the three-phase motor winding is connected this way, what kind of connection is it?
1Wye or 1Delta;
2Wye or 2Delta;
3Wye or 3Delta or....?

RE: Unknown motor connection

Three separate star windings. Are you sure there aren't any contactors missing from this arrangement?

RE: Unknown motor connection

(OP)
The wiring above is for run-time.
Motor is starting with part of winding (pws).

RE: Unknown motor connection

You are showing windings that probably don't exist.
It is probably a consequent pole connection or Dallander connection.
Motors with six individual windings are common in both IEC land and NEMA land.
There are no common motors with nine windings.

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

RE: Unknown motor connection

(OP)
This connection is not fictional but applied in a wide range of refrigerant compressors.
The figure below shows the same wiring in another way :


RE: Unknown motor connection

The first image shows three discrete star windings, as does the re-drawn one in the final image. There's no connection at the star point, to a neutral or to another winding's star point. The behaviour of the motor will depend on the physical displacement between the windings.

RE: Unknown motor connection

I would say it is 1 circuit Delta start and 3 circuit wye run

Muthu
www.edison.co.in

RE: Unknown motor connection

120/208 Volt supply?
Delta start with 104 across two windings?
Star run with 120 Volts across three windings?
Rather than a star/delta start, a part winding, delta/star start?
Is this a refrigeration set or an air conditioning set?
Can you give us a specific make and model?

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

RE: Unknown motor connection

Here is the delta start connection: A series delta for 50% line to line voltage across each winding rather than the familiar straight delta with 100% of line to line voltage across each winding.

Quote (OP, 13 Sept 19 06:33 )

Sorry for being slow to get my head around this one, EngRepair.
Wow. Over 50 years wandering from the Yukon Territory (Beside Alaska but often colder) to the Bay Islands and the Moskito Miskito Coast and there is still something new.

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

RE: Unknown motor connection

During running, each winding sees 57.7% of the line-line voltage.

During starting, 6 of the 9 windings see 50.0% of the line-line voltage. 1 winding from each phase is not connected.

It's a strange connection. Possibly done to make the contactor used to switch the motor to it's running connection smaller compared to other starting methods. Also eliminates the need for any contactor interlocking.

RE: Unknown motor connection

(OP)
3 Wye run-connection seems to me too.
But it is still confusing because the nameplate of such motors is marked with D / D or D / DD ("D" means: delta connection).



RE: Unknown motor connection

For discussion Lionel;
Star delta, The starting voltage = 57.7% Starting torque = 33%
This arrangement, The starting voltage is 50%/57.7% = 86% Starting torque = 75% Time two windings out of three = 50% torque.
Will this give better starting torque than a conventional star/delta start?
Does this agree with your figures?

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

RE: Unknown motor connection

This connection is interesting as it uses a series delta connection. And parallel star connections.
If my calculations are correct, The 50% of locked rotor torque should be enough to come up to speed.
A conventional star/delta start with 33% of locked rotor torque may stall or not come up to speed on a compressor.
I am familiar with the Copeland marke. I have worked on a lot of Copelands. All were DOL start.
Thank you for the new information.
Bill

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

RE: Unknown motor connection

Another interesting point.
The starting connection is similar to a consequent pole or Dallander connection.
While the run synchronous speed is 1500 RPM, the starting synchronous speed may be 750 RPM.
Comments?

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

RE: Unknown motor connection

I am with EngRepair

This is a 1/3th-2/3th Part Winding start connection. It is a three-layer winding where the firs layer is connected in one star and two layers remaining are paralleled and connected in 2-Y. The first layer has i.e X # Turns and Y # wire size and the second and third layers has 2 X # Turns and 2 Y wire size.

Regards

Petronila

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