Frequency of Starts for a Franklin Electric Submersible Pump Motor



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Home > Pumps & Wells > Well Pumps > Franklin Electric Frequency of Motor Starts

Franklin Electric Submersible Motors

Frequency of Starts


The average number of starts per day over a period of months or years influences the life of a submersible pumping system. Excessive cycling affects the life of control components such as pressure switches, starters, relays and capacitors. Rapid cycling can also cause motor spline damage, bearing damage, and motor overheating. All these conditions can lead to reduced motor life.

The pump size, tank size and other controls should be selected to keep the starts per day as low as practical for longest life. The maximum number of starts per 24-hour period is shown in Table 3.

Motors should run a minimum of one minute to dissipate heat build up from starting current. 6-inch and larger motors should have a minimum of 15 minutes between starts or starting attempts.

The size and condition of your precharged well tank is vital in keeping within these limits. In addition, you may consider a cycle stop valve in conjunction with your tank


  Table 3 Number of Starts
Motor Rating Max. Starts Per 24 Hr. Period
HP KW Single-Phase Three-Phase
Up to .75 HP Up to .55 300 300
1 thru 5.5 .75 thru 4 100 300
7.5 thru 30 5.5 thru 22 50 100*
40 and over 30 and over - 100

*Keeping starts per day within the recommended numbers provides the best system life. However, when used with a properly configured Reduced Voltage Starter (RSV) or Variable Frequency Drive (VFD), 7.5 thru 30 Hp three-phase motors can be started up to 200 times per 24 hour period.

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