i need the details about how to control the sysnchronous motor. ie reversal/ forward operations and on/off funtion of the motor with circuit explanation and programming also

Thanking you

With regards
S.K.Gajalakshmi
Engineer
Flashtech Envirosystems
Theni

 

Responding to S.K. Gajalakshmi's Feb 25, 4:07pm query... it is different than an induction motor, hence its "control" is different:

While the synchronous motor has advantages over the induction motor it has disadvantages. For example, it has no starting torque, therefore
requires an auxiliary starting method. Following are some of the topics you must consider:

a) Size: small; large?
b) Speed: slow; fast?
c) Type: standard; super-synchronous?
d) Starting: under load; unloaded?
e) Inertia of motor and driven-load?
f) Excitation: brushless; dc generator?

Please don't misconstrue the above as a negative response. But, its clear you need more help than can be provided on this list. So, start with self-help. The web is full of information.

Regards,
Phil Corso, PE {Boca Raton, FL, USA}
[[email protected]] ([email protected])

 

For Forward, reversal action of synchronous motor use a digital Cyclic timer to reverse current direction to reverse rotational direction.

Cyclic timer is available in Omron Brand at Chennai.

With Best Wishes,
P.Surianarayanan
CEO
VENTURES International
21, Saradha Nagar,
Virugambakkam,
Chennai-600 092
India
Phone: # 91-44-23774275
Mobile: # 91-9444046801
E-Mail: venturesintl @ hotmail.com
psurianarayanan @ yahoo.co.uk

 

I cannot be of good help... for my theni gal...
As you know, the motor is not inherently self-starting, it has to be started and brought up to synchronous or near synchronous speed by some other means before it is synchronised. It can operate at any desired power factor, either lagging or upf or leading...

Let me give explanation why it's not self starting. When you establish a rotating stator magnetic field using 3 phase AC supply field rotates at 120f/p. For the 2 pole, it's 3000 revolutions at 50 hz. At a particular instant the stator rotating magnetic field axis may coincide with rotor axis. With like poles of stator and rotor fields appearing nearer to each other, the rotor experiences a force of repulsion. Due to moment of inertia, the rotor takes some time for making a movement in response to this force of repulsion. But before the rotor makes a movement, in the next 0.01 second, stator rotating magnetic field completes a half revolution so that unlike poles of stator and rotor fields come closer. This causes a force of attraction to take place in the rotor... Thus at standstill condition, when the relative speed between the stator and rotor fields is larger, the rotor is unable to respond to both the forces of repulsion and attraction. the rotor is simply subjected to alternate forces of repulsion and attraction. Hence the syn motor is not inherently self-starting.

Motor can be started in many ways except that it can't be self started.

By an extra small 3 phase induction motor
or by providing cage/damper winding in pole faces
or by operating the pilot exciter as a DC motor...
if you are looking for detailed circuit layout, email me at nandakumar. gopal @ gmail. com The easiest I would say is method 1... using an induction motor of 25% capacity with same # of poles to be mechanically coupled together.