Xylem 19 001 251 R3 Floboy VFD Pumping System - Manual (Page 36)

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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.
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.
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.
Controller Device mounted in panel to control system operation. Also called Touch Screen
or HMI.
Control valve A valve designed to automatically open/close in order to maintain a specific set
point pressure, flow, or level.
Control variable A value that a control system monitors in order to perform some useful function.
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.
DC Direct Current. Such as a battery. The voltage is stable, and does not oscillate
(at least intentionally).
Digital A simple ON/OFF condition. For example, the presence or lack of a 120VAC
signal on a wire is a digital condition.
Flooded suction A type of system where the pumps (usually centrifugal) are fed by a pond or
other body of water at very low pressure (atmosphere, or just a few feet of
water column). Pumps for these systems must be carefully selected for low
NPSHR (Net Positive Suction Head Requirements) or cavitation and pump
damage can occur. Low inlet pressure safety is an excellent choice for these
systems.