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Partwinding
- Thread starter liviu2004
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bigbillnky
Electrical
Good moring
Part-winding start is a method of reducing inrush current at the startup of a motor. It is also used to prevent damage to the driven load caused by high starting torque when a motor is started across the line. Generally, a motor is specifically built in which the rotor is wound with 2 indentical sets of windings. Each winding accounts for 1/2 the total connected running load. The controller is wired in a manner in which only one set of windings are initially energized when the motor is started. The second set of windings are energized after a delayed period of time.
Hope this has helped
Bigbillnky,C.E.F.....(Chief Electrical Flunky)
Part-winding start is a method of reducing inrush current at the startup of a motor. It is also used to prevent damage to the driven load caused by high starting torque when a motor is started across the line. Generally, a motor is specifically built in which the rotor is wound with 2 indentical sets of windings. Each winding accounts for 1/2 the total connected running load. The controller is wired in a manner in which only one set of windings are initially energized when the motor is started. The second set of windings are energized after a delayed period of time.
Hope this has helped
Bigbillnky,C.E.F.....(Chief Electrical Flunky)
To finish his thought, if you are going to use a solid state starter you simply connect both sets as one (in parallel, not series!), and wire your soft starter as if it were a standard motor.
"Venditori de oleum-vipera non vigere excordis populi"
"Venditori de oleum-vipera non vigere excordis populi"
The part winding construction has lots of inconvinients that can damage the motor and do not develops a good speed- torque characteristc at high speed.
If you have the soft starter, follow jraef advise and make this motor full winding start rather than part winding.
You should connect the six or nine leads of the motor for the final step, following the wiring diagrams on the nameplate.
If you have the soft starter, follow jraef advise and make this motor full winding start rather than part winding.
You should connect the six or nine leads of the motor for the final step, following the wiring diagrams on the nameplate.
In a part winding motor you have two sets of stator windings, not 2 sets of rotor windings. A part winding start controls inrush current to some extent but not as well as some other starting methods. The second winding must be energized within about 2 seconds of the first. It is not a good method for controlling starting torque and current because of that and that winding resistance is rather low.
However, part winding start does allow use of 2 less expensive contactors instead of a single big contactor. The biggest single contactor that is not h#!!atiously expensive at 480 volts is 250 Horsepower. Even then, two 100 HP contactors will be less expensive than a 200 HP contactor.
Most air compressors that are 100 HP and larger use wye delta starting as that limits starting torque to 1/3 of across the line starting torque whcih saves a lot on gearbox cost. If you were to try to start a large compressor across the line you would actually break off gear teeth in the rotary screw compressor. Soft starters are starting to compete with wye delta starters.
However, part winding start does allow use of 2 less expensive contactors instead of a single big contactor. The biggest single contactor that is not h#!!atiously expensive at 480 volts is 250 Horsepower. Even then, two 100 HP contactors will be less expensive than a 200 HP contactor.
Most air compressors that are 100 HP and larger use wye delta starting as that limits starting torque to 1/3 of across the line starting torque whcih saves a lot on gearbox cost. If you were to try to start a large compressor across the line you would actually break off gear teeth in the rotary screw compressor. Soft starters are starting to compete with wye delta starters.
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