15 of 114M-AP-001-EN Rev. Q
Acronym / Term Definition
LED Light-Emitting Diode
Levitation
The elevation or suspension of the compressor shaft by the magnetic field created by the
magnetic bearings.
Line Reactor
A transformer-like device designed to introduce a specific amount of inductive reactance
into a circuit. When this occurs, it limits the change in current in the line, which in turn
filters the waveform and attenuates electrical noise and harmonics associated with an
inverter/drive output.
LLSV Liquid Line Solenoid Valve
LR Line Reactor
LRA Locked Rotor Amps
Mid Bus
A connection between the capacitors allowing them to be connected in series and in
parallel simultaneously. Two capacitors in a series make up the DC- and two in a series
make up the DC+, and those two sets of two are connected in parallel.
Modbus
A serial communications protocol published by Modicon in 1979 for use with its
programmable logic controllers (PLCs). It has become a de facto standard communications
protocol in industry, and is now the most commonly available means of connecting
industrial electronic devices. Modbus allows for communication between many devices
connected to the same network, for example a system that measures temperature and
humidity and communicates the results to a computer.
Monitor Program
A software program provided by Danfoss LLC that can be downloaded to a PC or laptop
computer to monitor, regulate, control or verify the operation of a compressor.
MOP Maximum Operating Pressure
Motor Back EMF
Back electromotive force is a voltage that occurs in electric motors where there is relative
motion between the armature of the motor and the external magnetic field and is also
a parameter used to evaluate the strength of the permanent magnets of the shaft. One
practical application is to use this phenomenon to indirectly measure motor speed as well
as estimate position.
NEC National Electric Code (www.necplus.org)
Nm Newton meter. A unit of torque. 1 Nm = 0.738 pound-force foot (lbf/f).
NTC
Negative Temperature Coefficient. Refers to thermistor characteristic. Decrease in
temperature results in a rise in resistance (ohms).
OEM Original Equipment Manufacturer
Open Impeller A compressor impeller with exposed vanes similar to a boat propeller or turbocharger.
PCB Printed Circuit Board
Permanent Magnet
Motor
A motor that has permanent magnetism as opposed to electromagnetism.
PLC Programmable Logic Controller
Pressure Ratio See “Compression Ratio”
Proximity Sensor
Sensors that are able to detect the presence of nearby objects without any physical
contact. A proximity sensor often emits an electromagnetic or electrostatic field, or a beam
of electromagnetic radiation (infrared, for instance), and looks for changes in the field or
return signal.
PWM Pulse Width Modulation
Radial Bearing Bearings that control the position of the shaft on the X and Y axis.
Rectifier A rectifier is an electrical device that converts AC current to pulsating DC current.
Resistor
A resistor is an electrical component that limits or regulates the flow of electrical current in
an electronic circuit.
RMA Return Material Authorization
SCR
Silicon-Controlled Rectifier. The SCR is a four-layer, solid-state device that controls current
and converts AC to DC.
Serial Driver
A PCB plug-in responsible for the operation of the IGV stepper motor and optional
expansion valves. It contains four relays for the solenoid valves, compressor status and
compressor run status respectively.
SDT Saturated Discharge Temperature
SEER Seasonal Energy Efficiency Ratio
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