Electrical driver start/stop 2

[roker]

hello,

according to the sequence of operation a pump with a 1HP electrical motor starts every 7 minutes for 2 minutes and stops for another 7 min and so on.
can the electrical motor be started and stopped for such a mode of operation? is there any recommendation for the maximal start/stop per aperiod of time?

regards,
roker

 

[Skogsgurra]

Pumps are low inertia loads. A 1 HP motor can take this load cycle with no problems at all.



Gunnar Englund

http://www.gke.org

 

[ccjersey]

If it is a single phase motor, Capacitor start or split phase with a centrifugal starting switch, the switch and or capacitor will take a beating. One thing that is commonly done is to add a resister between the capacitor terminals to prevent arcing of the switch contacts. Other than that a good quality capacitor is a wise investment.

We run 1hp centrifugal milk pumps which cycle on and off 2 to 3 times a minute for 6 or 7 hours 2 times a day. With the modifications described above they are very reliable and last for many years with only occasional capacitor and switch problems.

We also have a PSC design pump motor which eliminates the switch and is even more reliable. Lightning from thunder storms causes capacitor failure occasionally on those.

Jim

 

[aolalde]

Hi roker:

Starting limits are defined in NEMA MG1 standards for American motors.
For 1 HP application the more economical solution is that described. Consider the motor life expectancy between 2 to 3 years, replace it with a new motor when it will fail.

For large HP motors the described starting-stopping cycle should be avoided in spite of driving a light inertia pump.