GE Industrial Solutions ASTAT XT - Manual (Page 58)

58 • Starting Procedure
6.2.4.2
Stopping Curve
• Adjust Main Parameters as necessary (Starter Current, Motor Current, etc.)
• Set Soft Stop Curve and Ramp DOWN Time to their default values (Curve 0 and 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).
• Select Soft Stop Curve 1!! and increase Ramp DOWN Time to 15 seconds. Stop the pump and watch the
pressure gauge and the rate of closing of the check valve as the pump stops. Abrupt stopping of the pump and
motor will cause a loud audible noise emitted from the check valve.
• In most cases, “water hammer” is reduced. If “water hammer” persists, increase the time to 25 seconds (confirm
with motor manufacturer) and try again.
• If “water hammer” persists, increase the Soft Stop Curve setting to 2!! or 3!!. Each increase in the Soft
Stop Curve
will reduce the abrupt stop of the pump, thus preventing the “water hammer” phenomenon.
6.2.4.3
End Torque During Soft-Stopping a Pump Motor
While decelerating, the check valve may close before Ramp DOWN Time has elapsed, thus allowing current to flow
through stator winding causing unnecessary heat. Select End Torque sensitivity to 1 and stop the pump, then
confirm that the current stopped flowing through the motor shortly after the check valve closed.
If current still flows more than 3-5 seconds after check valve closure, increase End Torque (up to a maximum
value of 10) to stop current flow earlier.