Part winding Motor - Acceleration Time

[NickParker]

Typically, how long does the part winding motor will take to accelerate to full speed ? I have part winding motor for a compressor unit (HVAC application). The compressor type is semi-hermetic reciprocating compressor unit. Since this is a part winding, will it have two inrush current? I'm about to set the breaker settings for this feeder.

The voltage rating of the motor is three phase, 460V, 60Hz.

Thanks!

 

[waross]

Typically, how long does the part winding motor will take to accelerate to full speed ?
IT DEPENDS.
This is more load dependent than motor dependent
The second winding should come in when the acceleration starts to taper off.

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

 

[7anoter4]

According to Toshont Power Products
“load must be able to be accelerated from zero to full rated speed in only two or three seconds, with only half the motor capacity.”
Application Guides | Toshont Power Products

 

[edison123]

Idea of part winding is to reduce the inrush current. As Bill says, switch in the balance winding when the inrush current has dropped to around 20 to 35% of rated current. The starting time will depend on your motor's starting torque and the inertia of the load. It can be from 3 to even 90 seconds.

Muthu

http://www.edison.co.in

 

[NickParker]

This compressor has a part winding motor (PW)
For Part Winding motor, there is 2 current peaks during starting sequence ;
1st current peak takes from 200 to 400 ms (high load)
2nd current peak takes from 30 to 40 ms (lower load, motor is already running)
(figures valid if you apply the nominal voltage / frequency to the motor)
The time delay between PW1 and PW2 must not exceed 0,5 second.

You can set the short time settings at 1s.

The above is the response I got from the manufacturer. I wonder, is it possible to accelerate within 1s. Again I asked the manufacturer to confirm and I would get reply at least a week after.

 

[che12345]

Dear Mr NickParker
Introduction: This compressor has a part winding motor (PW)
.....The time delay between PW1 and PW2 must not exceed 0,5 second....
....You can set the short time settings at 1s.
.... I wonder, is it possible to accelerate within 1s.

Q1. The time delay between PW1 and PW2 must not exceed 0,5 second....
A1. This time delay [ " must not exceed 0,5s "] refers to the [transitional switching time] i.e. the switching time transferring [at the end of the low-speed over to the high-speed]. It is [not] the time (from the starting of low-speed) up to the time of transfer to high-speed.
If the [transitional switching time] is too long, the speed will drop. It would create a (bigger speed difference) when transferred to high-speed, which may not be favorable to the load/mechanical parts etc.
FYI: 1. The time it takes [from stand-still to full low-speed] is dependent on the difference between the motor low-speed torque and the low-speed low torque. e.g 5...10s etc.
2. Transfer from (low-speed to high-speed) should take place when the low-speed current "flats" out i.e. when the motor low-speed torque = low-speed load torque.
3. [transitional switching time] from (end of low-speed to the high-speed) should [not] exceed 0.5s .
4. The time it takes from [beginning of high-speed to full high-speed] is dependent on the difference between the [motor high-speed torque and the high-speed load torque]. e.g. 5...20s etc

Che Kuan Yau (Singapore)