ITT PumpSmart PS220, Руководство по конфигурации и эксплуатации

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PS220 Configuration & Operation Guide
PS220 174
Functions &
Features
EXAMPLE – A pump configured for constant pressure draws from a tank. The level in the tank varies
greatly, and occasionally drops enough that the pump begins to cavitate. The Basic Pump Protection on
the PS220 would limit the speed of the pump or shut it off. Using the Multivariable Control feature would
allow for pumping to continue, but at a reduced and allowable rate to prevent any harm to the pump, or
the pumping system.
A suction pressure transmitter would need to be added and wired into any unused Analog Input (AI2 in
this example). AI1 has already been configured for the primary control of the pump. The AI2 signal would
then be configured such that when the suction pressure is sufficient, the PS220 would be controlled to
the setpoint (reference) value chosen. When the suction pressure dropped below a certain value it would
start to change/offset the setpoint reference) based on the new scaling. In this case it would begin to
lower the set point.
In the above diagram, the set-point (reference) is 50psi. When the secondary process transmitter (TX2) is
below 5ft (LEVEL 1) of tank level, it will begin to scale back the set-point linearly from 50psig to 10psi (SP
LO) at 2ft (LO INTRCPT). When the secondary process transmitter (TX2) reaches 16ft of tank level (Level 2),
it will increase the set-point linearly from 50psi to 75psi (SP HI) at 18ft (HI INTRCPT).
Note:
To disable this functionality, you MUST re-run the Basic Startup and Process Control Wizards.