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M-AP-001-EN Rev. N
1.4 Denitions
Table 1-2 - Denitions
Introduction
Acronym / Term Denition
Alarms
Alarms indicate a condition at the limit of the normal operating envelope. compressor
alarms will still allow the compressor to run, but speed is reduced to bring the alarm
condition under the alarm limit.
AHRI Air-Conditioning, Heating, and Refrigeration Institute (www.ari.org; www.ahrinet.org)
ASHRAE
American Society of Heating Refrigeration and Air-Conditioning Engineers (www.ashrae.
org)
ASIC Application-Specic Integrated Circuit
ASTM American Society for Testing and Materials (www.astm.org)
Axial Bearing Bearing that controls the horizontal movement (Z axis) of the motor shaft
Backplane
A PCB for the purpose of power and control signal transmission. Many other components
connect to this board.
Balance Piston
Component within the compressor that provides primary counter to impeller thrust.
Impeller thrust is trimmed by the axial bearing.
BMCC
Bearing Motor compressor Controller. The BMCC is the central processor board of the
compressor. Based on its sensor inputs, it controls the bearing and motor system and
maintains compressor control within the operating limits.
Bus Bars Heavy-gauge metal conductors used to transfer large electrical currents
Capacitor A passive component that stores energy in the form of an electrostatic eld
Cavity Sensor
NTC temperature sensor located behind the Backplane for the purpose of sensing motor-
cooling vapor temperature. Provides overheat protection to motor windings.
CE
Conformance European. The CE marking (also known as CE mark) is a mandatory
conformity mark on many products placed on the single market in the European Economic
Area. The CE marking certies that a product has met EU health, safety, and environmental
requirements, which ensure consumer safety.
Choke
Denitive point on compressor map where mass ow rate is at maximum for compressor
speed and lift conditions.
Compression
Ratio
The absolute discharge pressure divided by the absolute suction pressure
CSA Canadian Standards Association (www.csa.ca)
DC Bus
High DC voltage simultaneously connected to multiple compressor components via
metallic bus bars, including the capacitors
DC Capacitor
Assembly
An assembly of four DC capacitors, four bleeder resistors, and positive and negative bus
bars
DC-DC Converter
DC-DC converters supply and electrically isolate the high and low DC voltages that are
required by the control circuits. When the compressor is switched on, the High-Voltage
(HV) DC-DC Converter receives its 15VAC supply from the Soft-Start Board. Once the DC
bus voltage has risen to a pre-determined level, the HV DC-DC Converter’s onboard circuits
are powered by the DC bus (460-900VDC). The HV DC-DC Converter delivers +24VDC (with
respect to 0V) to the Backplane, and HV+ (+250VDC with respect to HV-) to the magnetic
Bearing Pulse Width Modulation (PWM) Amplier via the Backplane.
Dielectric
A dielectric is a nonconducting substance. Although “dielectric” and “insulator” are
generally considered synonymous, the term “dielectric” is more often used when
considering the eect of alternating electric elds on the substance while “insulator” is
more often used when the material is being used to withstand a high electric eld.
Diuser
Part of a centrifugal compressor in the uid module that transforms the high-velocity, low-
pressure gas exiting the impeller into higher-pressure, low-velocity gas discharged into the
condenser.
Diode A two-terminal device between which current may ow in one direction only
Down-Trip Voltage
A voltage threshold where, if the incoming AC voltage drops below it, the SCRs will shut
down
D-Sub
A type of connector/plug (male and female) for control wiring. The RS-232 and large
connectors on either side of the I/O cable are both types of D-Sub connectors.
DTC Danfoss Turbocor compressors Inc.
EEPROM
Electrically Erasable Programmable Read Only Memory. A small chip holds bits of data code
that can be rewritten and erased by an electrical charge, one byte at a time. EEPROM data
cannot be selectively rewritten; the entire chip must be erased and rewritten to update its
contents.
EER Energy Eciency Ratio