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Why does Schneider Electric offer servo motors with "T" winding and "P" winding? What is the difference between these types and which type should I select?

Here is a basic explanation without being too technical....

The speed / torque curve of a servo motor is dependent on how much voltage and current is applied to the windings of the motor.
Current effects torque from the motor, while voltage effects speed.
Voltage influences the "rise time" of the magnetic field within a motor.
The higher the voltage the faster the rise time of the magnetic field within the motor.
The faster the rise time the higher rotational speed.

Motor manufacturers can decide how they want to wind the stator within a motor.
The motor winding can be designed in such a way that the motor can achieve higher speeds even if used at lower operating voltages.
However, this design means the motor winding then has a lower maximum operating voltage.

Such is the case with a motor with a "T" winding.
The "T" winding motor is optimized for higher rotational speeds when used in conjunction with a drive that operates from a lower mains voltage (single phase mains up to 240vac), while the "P" winding is optimized for use with drives that have a higher mains voltage ( up to 480vac 3 phase )

A "T" winding motor will not function if connected to a drive designed for use on 3 phase mains voltage.  
The firmware within the drive reads the motor EPROM via the encoder cable and knows what motor type is connected.
Drives designed for use on 3 phase mains will not permit itself to be enabled if a motor with a "T" winding is found to be connected and the drive will display a fault code.
If the drive permitted itself to enable the lower voltage rated winding could fail because it is not designed to withstand higher voltages derived in a 3 phase mains powered drive..

Motors with the "T" winding are optimized for maximum performance at lower mains voltages.
This means the "T" winding motor will actually outperform a "P" winding when used with a drive that is connected to 230vac single phase mains.

Manufactures need to design motors that will be compatible with as many situations as reasonable, this is the reason we offer motors with "T" winding and motors with "P" winding.

Example 1.  A machine needs a high speed servo but only has access to single phase mains voltage of 230vac to power the drive.
This machine designed should use motors with "T" windings to achieve the greatest speed possible at this lower mains voltage.

Example 2.  Machine needs a high speed servo and the drive will be operated from 480vac 3 phase mains.
This machine would use motor with "P" winding taking advantage of the motor type with the highest speed capability.
Remember.... T winding motor won't work on 3 phase mains, this is because a 3 phase drive will not permit itself to be enabled if a "T" winding motor is used 

This is the reason for the two winding types.

Attached to this article are two speed/torque charts that can be used for comparison of two motors of a similar model with T winding and P winding connected to the same power class drives but operated from 230 single phase and 480 3 phase mains respectively. 



rev 7-11-16
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