CMC TECHNICAL REFERENCE MANUAL
1X36003 Version 2.52
1996-1999 Ingersoll-Rand Company
Date of Issue: 18-Oct-1999
1
Glossary
The following glossary is generic; therefore,
some terms do not apply to all CMC systems.
AB —
See Allen-Bradley.
Absolute Address —
For Modbus compliant devices, the
specific memory location for a coil, discrete input, register or
analog input. The address is a five-digit number.
Accelerometer
— An instrument used to measure
acceleration. These instruments are typically used for bearing
analysis.
Actuator
— The device on a control valve that provides the
power to move the valve to a position. Typically, this power is
supplied through control air to open (for the inlet valve) and
close (for the bypass valve). For “fail-safe” operation, a
spring is used to drive the valve in the opposite direction.
Address
— This term is used by PLC manufacturers to
indicate a specific memory location within the unit. These
locations typically reference the value for data items like
analog inputs, analog outputs, digital inputs, digital outputs,
coils and intermediate computational states. Through these
memory locations, the current system pressure, first stage
vibration and discharge air temperature can be determined.
Alarm
— The term used to indicate that an abnormal condition
exists that should be addressed by an operator. This
condition has not reached a level that would shut down the
compressor.
Alert
— See Alarm.
Allen-Bradley
— A manufacturer of control products, most
notably PLCs. These PLCs are used for various industrial
applications including controlling compressors.
American Wire Gage (AWG) —
The measurement system
used to indicate the diameter of the wire. The gage number
increases as the wire diameter decreases.
Analog Input
— An electrical device, which represents a
specific real world pressure, temperature, vibration or
current. As these items fluctuate, the electrical signal to and
from the microprocessor board also fluctuates proportionally
to the amount of change. The electrical signal is typically in the
form of a current that ranges from 4 to 20 milli-amps in
magnitude.
Analog Output
— An electrical signal, which typically
represents the inlet and bypass valve position. As these
valves fluctuate, the electrical signal to and from the
microprocessor board also fluctuates proportionally to the
amount of change. The electrical signal is typically in the form
of a current that ranges from 4 to 20 milli-amps in magnitude.
Auto-Cold Start —
A control mode that automatically
energizes the panel power, opens cooling water flow valve
to the coolers, turns on seal air, starts and loads the
compressor on a low pressure condition.
Auto-Dual —
The control mode that automatically unloads
a modulating compressor when the bypass valve position
reaches a specified value or the check valve closes. Once
unloaded, this control mode will automatically reload the
compressor when the system pressure drops below a
specified value.
Auto-Dual Unload Timer
The time delay, in seconds,
at which the machine will be unloaded after the bypass
valve has passed and stayed below the unload point when
Autodual is active.
Auto-Hot Start —
A control mode that automatically starts
and loads the compressor on a low-pressure condition.
Auto-Reload —
The portion of Auto-Dual control mode that
automatically reloads the compressor when the pressure
drops below a specified value.
Auto-Start Pressure
The system pressure, in
pressure setpoint units, at which the machine will start
when either auto hot or cold start is active.
Axial Position
— The position of the rotating assembly
with respect to the horizontal axis of the pinion.
Baud Rate —
Unit of signaling speed for data
communications. The speed in baud is the number of line
changes (in frequency, amplitude, etc.) or events per
second. At low speeds each event represents only one bit
and baud rate equals bits per second. As speed increases,
each event represents more than one bit, and baud rate
does not truly equal bits per second.
BCM —
Base Control Module. The device of the CMC that
receives all of the compressor inputs and outputs and
makes decisions about how the compressor is to operate.
Binary Signal
— The type of signal used in
communications. Binary refers to the smallest size of data
being transmitted, a bit.
Blow-off Valve
— Also know as a bypass valve or anti-
surge valve. This valve protects the compressor from
surge by bypassing a percentage of the compressed air to
the atmosphere, which results in keeping the compressor
loaded above the surge point.
BPS
— Bits per second. Unit of signaling speed for data
communications.
Bypass Valve
— See blow-off valve.
CE Mark —
The CE Mark is a combination of various
individual European standards into one set of standards for
the entire European community. The Mark is a self
declaration and self marking process. Once you have
proven that the particular equipment meets the
requirements of CE Mark and have the data to back it up,
you may mark the product with the CE Mark.
Citect —
One of many SCADA software packages that
can be used for air system integration.
