Part Winding Start Motors
Part Winding Start Motors
(OP)
I am having a disagreement with another electician over the size of internal windings in a part winding start motor. He claims the start windings are wound with larger wire since they experience a higher current inrush. All my literature says the motor draws approximately 65% inrush at start up and cannot find any information on the windings. Can you help me settle this.
Thank you in advance,
viperone.
Thank you in advance,
viperone.





RE: Part Winding Start Motors
Part start windings normally use the same size conductors, but only use a % of the winding on start up.....i.e. 60/40....using 60% of the windings for a softer, or lower current start up.
hope this is of some help
Jeff
www.motors-direct.co.uk
RE: Part Winding Start Motors
In general part-winding-start motors have the standard type and the winding almost that of a standard dual voltage motor.
Special applications could have variations of this “50% standard array”. Motors with two poles could develop cusps in the speed-torque curve when part-winding started.
RE: Part Winding Start Motors
Your buddy is wrong. He buys the next beer.
"Venditori de oleum-vipera non vigere excordis populi"
RE: Part Winding Start Motors
There is one case where the part winding start leads are larger. For 9-lead, delta connected, dual voltage, suitable for PWS on the low voltage, the 1-2-3 leads are normally larger than the remaining 6 leads. However this is for cost reasons rather than current sizing
Also some modern motors do not use true "part" windings anymore. They use a center tapped delta -- which uses the whole winding to start, but has the characteristics of a true "part" winding. This confuses some electricans who expect a split winding and find continuity on all leads.
to jrael:
There are some special application motors which must be sized for starting --- high inertia centrifuges comes to mind.
to aolalde:
There are other fractional part winding starts -- i.e. 2/3 part winding, where the current balance is unequal.
to motorsdirect:
I would be interested in seeing a 60/40 connection.