Xylem 19 001 351R2 PACE Integrated Pump Controller Human Machine Interface (HMI) for the Silent Storm VFD Pumping System – User Guide - Manual (Page 27)

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Phase monitor A device that analyzes incoming voltage and determines whether all voltage
parameters are acceptable and the phase sequence is correct.
PLC Programmable Logic Controller. A very robust/rugged computer designed for
equipment control in harsh environments.
PM pump Pressure Maintenance Pump. Handles very light flow rates and leaks to
prevent the main pumps from cycling.
Pressure reducing valve (PRV) A control valve designed strictly for maintaining a specific downstream
pressure.
Pressure transducer A device that converts actual pressure to a 4-20 mA signal that is input into
the PLC which converts it back to an actual pressure reading.
PSI Pounds per square inch. Units of pressure for US use.
Relay This is a normally open or normally closed device that changes output state
when it is energized or de-energized and sends or removes a 120VAC signal
to the PLC.
SCADA Supervisory Control And Data Acquisition.
Setpoint The desired situation for a control variable. If the user wanted the irrigation
system to operate at 120 PSI, that would be the setpoint for the controller.
Speed test The method used to shut down a VSP during normal automatic operation.
Transfer pump A pump designed to move water from one reservoir to another.
Units Gives context to numbers in the PLC. Units describe what the number is
about, such as PSI, GPM.
VFD Variable frequency drive. This allows a pump to run at variable speeds.