118 • Start Procedure for Medium voltage Motor
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Select SOFT STOP CURVE 2!! and increase DECELERATION 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 3!!, or 4!!. Each increase in the
SOFT STOP CURVE will reduce the abrupt stop of the pump, thus preventing the “water hammer”
phenomenon.
13.5.4.3
FINAL TORQUE During Soft-Stopping a Pump Motor
While decelerating, the check valve may close before DECELERATION TIME has elapsed, thus allowing
current to flow through stator winding causing unnecessary heat. Select FINAL 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 FINAL TORQUE (up to a
maximum value of 10) to stop current flow earlier.
13.6
How to set MPS-3000 and DPM-10 when installed with HRVS-DN
If MPS-3000 (Solcon motor protection) and/or DPM-10 (Solcon digital power meter) are integrated in the
HRVS-DN cabinet in a way that voltage readings are from the EPT and current measurements are from the
HRVS-DN internal CTs special attention must be given to the setting of these units.
Before setting the MPS-3000, read the MPS-3000 instruction manual.
Before setting the DPM-10, read the DPM-10 instruction manual.
If the MPS and DPM-10 use separate (not the internal soft starter) CTs and PTs (current and voltage
transformers), then set all MPS and DPM-10 parameters according to the instruction manual.
If, however the MPS and DPM-10 use the HRVS-DN Internal CTs and Electronic Potential Transformer (EPT),
a number of parameter settings must be performed as explained below.
Inside the soft starter, there is an EPT. Its “primary” rated voltage is equal to the starter rated voltage. Its
“secondary” rated voltage is 120VAC.
Inside the soft starter, special CTs are used. Their primary rated current equals to the starter rated current.
Their secondary rated current is 2A. The secondary current is connected to the MPS-3000 5A input and to the
DPM-10 5A input.
