PID Control
Introduction
The built-in PID of the G7 can be used to maintain a constant process variable such as flow,
pressure, temperature, and level. In the example below, the drive is used to vary the speed of the
motor/pump to maintain a constant pressure at the output of the pump. As the valves on the output of
the pump are opened, the pressure goes low. The drive senses this via a 4-20 mA feedback signal
and speeds up to increase pressure up to the desired level. The drive will slow the motor/pump down
as the valves close. The rate at which the drive responds to changes is adjustable via three
parameters (Proportional Gain, Integral Time, and Differential Time) and will have to be field-tuned.
Later in this guideline, PID applications will be discussed in general.
Connections
* For additional assistance, please contact Toshiba Adjustable Speed Drive Marketing Dept. at (800) 872-2192
9
Check your transducer’s schematic for connection information. The above diagram is typical for a loop-powered transducer.
Separately powered isolated transducers feed into the ‘II’ and “CC” terminals. If your transducer is not isolated, order an isolated
input board. The inputs to the standard G7 are not isolated; do not connect the ‘CC’ terminal to ground.
Output Flow
VALVES
//
//
MOTOR
D/A
-
Transduce
Area in which constant
pressure is desired
II
CC
P24
G7
PUMP
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