REDUCED VOLTAGE STARTERS
This month’s technical topic is REDUCED VOLTAGE STARTERS. One of the misconceptions about these devices is that their function is to protect the motor. This is not the case, and as a matter of fact, all Franklin 3-phase submersible motors are suitable for full-voltage starting. Under this condition the motor speed goes from zero to full speed within a half-second or less. Simultaneously, the motor current goes from zero to locked rotor amps, then drops to running amps at full speed. Although it doesn’t harm the motor, this may dim lights, cause momentary voltage dips to other electrical equipment, and shock load power distribution transformers.
Reduced voltage starters limit this voltage dip, and power companies often require them. Another reason for a reduced-voltage starter is to reduce motor starting torque. That, in turn, reduces the stress on shafts, couplings, and discharge piping. In addition, reduced-voltage starters slow the rapid acceleration of the water on start-up. This helps to control upthrust and water hammer. Continue reading