117 • Start Procedure for Medium voltage Motor
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13.5.3.1
Special Starting – Using DUAL ADJUSTMENT – Wiring Diagram
13.5.4
Choosing a Suitable Pump Curve (Centrifugal Pumps)
13.5.4.1
Starting
Curve
Adjust MAIN PARAMETERS as necessary (FLA, FLC, etc.).
Set STARTING CURVE, ACCELERATION TIME, CURRENT LIMIT, and INITIAL VOLTAGE to their default
values (curve 1, 10 sec., 400% and 30% respectively).
Start the pump while watching the pressure gauge as the pump starts and look for overshooting (“pressure
surge”) of the gauge needle above the target pressure. In case of over pressure, choose a peak torque
reduction curve (SOFT START CURVE 2!!).
Set SOFT START CURVE 2!!, increase ACCELERATION TIME to 15 seconds and reduce CURRENT LIMIT
to 350%. Start the pump and watch the pressure gauge while the pump starts.
In most cases, overshooting is reduced. If the overshoot persists, increase ACCELERATION TIME to 25
seconds (confirm with motor manufacturer) and try again.
If the overpressure persists, increase the SOFT START CURVE setting to 3!!, or 4!!, if necessary. Each
increase in the SOFT START CURVE setting will reduce the peak torque, thus reducing the overpressure
and preventing “pressure surge” during start.
13.5.4.2
Stopping
Curve
Adjust MAIN PARAMETERS as necessary (FLA, FLC, etc.)
Set SOFT STOP CURVE and DECELERATION TIME, to their default values (curve 1, 10 sec.,
respectively).
Stop the pump, watching the pressure gauge and check valve as the pump stops. Look for overshooting
(“water hammer”) of the gauge (abruptly stops the pump and the motor).
