38 | P a g e
First, attempt to control pressure by adjusting parameter PROPORTIONAL GAIN, leaving
parameter INTEGRAL GAIN at the default value of 15. If adequate control cannot be
obtained by adjusting proportional gain, set proportional gain at the value that gives the
best control, then adjust integral gain to improve pressure control.
For difficult-to-control systems, a derivative term can be introduced for PID control, which
can help control pressure oscillation and overshoot. Increase the value of parameter
DERIVATIVE GAIN to a value greater than zero to enable PID control. This parameter
should be used only when necessary as it tends to amplify noise in the transducer signal.
The system may become unstable. The parameters PID FILTER GAIN and PID FILTER
TIME help to prevent overshoot. It may be advisable to contact the factory for assistance
when using PID control for the first time.
In conceptual terms, proportional gain affects how quickly the system responds to pressure
changes and integral gain affects the accuracy of pressure tracking. Adjusting ramp times
can also be considered. Increasing ramp time will damp response to pressure changes,
while decreasing ramp time will quicken the response.
CAUTION: Long ramp times can interfere with PI control of constant pressure. It is
advisable to start with factory default ramp times.
Pressure Control at Minimum Speed
There is a possibility of conflict between the minimum pump speed setting, controlled by
the parameter MIN FREQUENCY, and the pressure setting of the transducer. That is, if
under no-flow conditions the pump at its minimum speed setting produces a pressure
greater than the desired set-point, either the minimum speed will have to be reduced or the
pressure set-point will have to be increased. Most pumps should not produce enough
pressure head at 30Hz for this to be an issue.
7.4 PerfectPressure™ Setup – Analog Constant Pressure
Upon the first initialization of the unit (or after restoring factory defaults of all parameters
using the Two Button Reset Procedure, page 21) the drive will prompt the user to select or
decline a quick setup for constant pressure. The display will read SETUP CONSTANT
PRESSURE YES(ENTER)/NO(HOME). Press the ENTER key to set up PerfectPressure™
or the HOME key to decline. Basic parameters for analog constant pressure can be set
without navigating through the complete menu options.
Follow this procedure to set up Perfect Pressure™:
1. SETUP CONSTANT PRESSURE YES(ENTER)/NO(HOME) - Press the ENTER key
to proceed.
2. INPUT VOLTAGE - This parameter sets the operating voltage of the motor to either
120 V or 240 V. Select and press ENTER to proceed.
3. CONSTANT PRESSURE – Use this parameter to select DIGITAL, ANALOG, or NO
to determine how the drive will control the motor.
4. RESPONSE TIME – This determines how quickly the drive will respond to pressure
fluctuations due to site-specific pipe and tank configurations. Select QUICK for large
systems, AVERAGE for medium systems, and SLOW for small systems. Select and
press ENTER to proceed.
5. MOTOR TYPE – Used to select either 2-Wire Motor or 3-Wire Motor. 2-Wire motors
have a start capacitor built-in while 3-Wire motors utilize a start capacitor in the drive.
6. MOTOR MANUFACTURER - This allows the user to select from a list of common
motor manufacturers and tunes the MOTOR PHASE ANGLE. If the motor being
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