Emerson Tescom ER5000 Series, User Manual, Page: 48 / 248

ER5000 —
48
Glossary of Terms
Pressure Reducing Regulator
Regulator that reduces high-pressure supplies of gas or liquid to a
safe or usable level for an application.
Process Line
Area within a system where the activity takes place that is
controlled by the PID controller, such as the pressure within a
pipeline or vessel. External sensors send
Feedback from the process
line to the controller.
Profile
Command sequence, created using The Profile Builder Panel
in the ERTune™ program, which can be downloaded to the
control board of the ER5000. Guides the ER5000 through a
set of actions that may include multiple
Setpoint changes,
modification of response characteristics and other internal
Variables based on real-time operational conditions and, in “F”
model controllers, precisely timed digital inputs and outputs.
Profiles may also be saved to a PC for future use.
Proportional
The component of a controller’s response that is a direct function
of the
Error generated by the current level of Feedback from
the system.
Pulse Deadband
Stop-band filter that deactivates Pulse Mode within a set
percentage range around Setpoint .
Pulse Mode
Refer to The Pulse Mode Panel for a complete description of
this feature.
Pulse Width Modulation (PWM)
Method of controlling a device such as a mechanical valve using
the control signal from a digital microprocessor (which can only
be ON or OFF) by varying the amount of time during a given cycle
when the ON signal is being sent.
The proportion of time that the signal is ON, from 0% to 100% of
the cycle, is known as the “duty cycle”. Because of mechanical lag
(the amount of time it takes for the valve to physically respond
to the instantaneous change in signal), the valve is constantly
“catching up” with the ON/OFF control signal in direct proportion
to the duty cycle. For example, a duty cycle of 75% results in a valve
that is approximately three-quarters open during that cycle.
The inlet and exhaust valves in the ER5000 are both PWM driven,
with a cycle time of 25 milliseconds.