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There are 3 potentiometers graded from A to E, but not graded in either seconds or Volts, which can be confusing to customers.
Start Time: voltage rise ramp time (Caution: this is not the acceleration ramp)
Stop Time: voltage fall ramp time (not deceleration)
Initial Voltage: initial voltage setting
Purpose of adjustment
This device is used to attenuate DOL starting in motors, so as to limit surges which may damage the mechanism. Neither the starting times nor the deceleration times are rated.
Setting to obtain the maximum starting torque
If Start Time is at Min. (A) and Initial Voltage is at Max. (E), the starter generates a DOL start with undesirable torque surges which are likely to damage the mechanism.
Setting to obtain the most gradual starting torque
If Start Time is at Max. (E) and Initial Voltage is at Min. (A), the starter generates a very long voltage ramp with gradual torque increase which eliminates mechanical shocks.
However, if the application requires a high starting torque, the starter is slow to deliver sufficient torque, which causes the motor to overheat and trip on a thermal overload fault.
Method of set up
Set both potentiometers to C and start. Two scenarios are possible:
The application starts correctly; it is still possible to increase the Start Time and decrease the Initial Voltage if necessary, although not by too much as this then introduces the risk of not starting.
The application does not start; increase the Initial Voltage and decrease the Start Time.
If the Start Time potentiometer is down at the minimum level A and the Initial Voltage potentiometer is up at the maximum level E, increase the drive rating.