Edwards GXS Series User Manual

9.11 How to use the PID pressure control
The pump has a built‑in PID pressure control and auto tune feature that can adjust the
dry pump speed when the pump is on‑process so that the pressure reading of the
pressure sensor matches the supplied PID setpoint. We recommend that the PID is auto
tuned aer the PID setpoint is adjusted.
Figure 67 The simplied system diagram
Classical PID equaon
Where:
u is the control signal.
e is the control error.
K
c
is the gain for a proporonal controller.
T
i
is the parameter that scales the integral controller.
T
d
is the parameter that scales the derivave controller.
t is the me taken for error measurement.
b is the set point value of the signal, also known as bias or oset.
On the pump, the Kc, T
i
and T
d
parameters and the me constant can either be set by
the user or the pump can perform an auto tune that calculates these parameters based
on the response of the system at the setpoint pressure.
The pump PID pressure control sequence is designed to work with our strain gauge or
acve Pirani gauge (available as accessories). Due to inaccuracies in the gauges, we do
not recommend trying to control below 20 mbar with a strain gauge. Refer to Using a
dierent gauge on page 149 to use a dierent pressure sensor.
The following menus are used by the PDT to congure and use the PID funconality.
Page 148
M58800880_H - Pump display terminal

Edwards GXS Series Specifications

General

Brand	Edwards
Model	GXS Series
Category	Water Pump
Language	English