Xylem 19 001 200 R2 SILENT STORM VFD Pumping System - Manual (Page 32)

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GLOSSARY OF TERMS
AC Alternating Current. The voltage, and therefore current, constantly oscillates
positive and negative. For North America, the line frequency is 60 Hz. Some
other areas of the world use 50 Hz.
Across-the-line (XL) Applying 100% of line voltage to a motor during startup and run. A simple large
relay with a contact for each power phase (for 3 phase) is used to control the
motor OFF/ON.
Analog A signal that varies in some respect (voltage, current, frequency) in order to
convey the value of some real world information (i.e. pressure, flow, temperature
etc). A control system can take action based on the value of such a signal.
Internally, the signal will be converted to some number based on the value of the
signal.
Automatic lake screen (ALS) A screen on the intake flume of the pump station, between the irrigation
pond and the wet well, which is designed to be self cleaning by using a jet of
clean water spraying from the inside-out during use.
Booster A pump designed to increase the pressure of a pressurized irrigation line. This is
usually used to move pressurized water from a lower to higher elevation area of
the golf course.
Calibration The act of or specific values used to scale the output of a measurement device to
read real-world values.
Canned turbine See vertical turbine.
Chemical injection The process of adding chemicals to irrigation water to fertilize or medicate
turfgrass.
Combo A capacity level representing a predefined group of pumps on a station. Normally
Combos are defined as follows:
Combo 1 Normally the PM pump.
Combo 2 Lead pump. Normally the VSP.
Combo 3 Lead pump and first lag pump.
Combo 4 Lead pump and two lag pumps.
Control valve A valve designed to automatically open/close in order to maintain a specific
setpoint pressure, flow, or level.
Control variable A value that a control system monitors in order to perform some useful function.
Conventional Refers to fixed-speed pump systems using a pressure reducing valve for pressure
control.
CPU Central processing unit. The part of the PLC that stores and allows manipulation
of the program, in conjunction with an EEPROM chip.
Cycle time The number of times an hour that a pump (PM or main pump) cycles on and off.
Cycling This condition occurs when conditions require a pump to start if no pump is
running, but require a pump to stop if a pump is running. This is excessive starting
and stopping of one or more pumps and can be damaging to the equipment if
allowed to continue.