58 | P a g e
5. ENABLE RESTARTS - YES(ENTER)/NO(HOME) – enabling restarts controls the ability of the
drive to automatically restart after a power failure. The drive will initialize in AUTO mode after
power is restored if YES is selected. If NO is selected, the drive will remain OFF when power is
restored.
6. OVERCURRENT LIMIT – Setting for motor overload protection (service factor amp rating for
the motor).
CAUTION: Most submersible pump motor manufacturers require the motor to reach 30 Hz within
one second in order to protect the pump from damage. Selecting NO for the parameter above will
override the factory default ramp time of 0-30 Hz in one second.
This quick setup of constant pressure should provide good pressure control in most situations. It is
advisable to read the entire section on constant pressure control for a complete explanation of constant
pressure control methods. Refer to Table 15, for expanded menu options to fine tune the constant
pressure system.
7.3 Analog Constant Pressure Systems
The analog CP system uses an analog pressure transducer connected to the analog input (I1+ and I1-
or I2+ and I2-) on the control terminals (see Figure 19 for one-line and wiring diagrams). A normally-
closed emergency over-pressure switch connected to the AUX2 terminals is also recommended. These
are used in conjunction with the internal firmware of the drive to implement a constant pressure water
system.
The drive uses a proportional-integral (PI) or proportional-integral-derivative (PID) controller in the
feedback loop for constant pressure control. This type of controller has a gain adjustment which must
be tuned by the user to obtain optimum performance for each particular application. Phase
Technologies has also developed a proprietary controller, Simple Mode, which requires minimal tuning.
When the PROPORTIONAL GAIN parameter is set at the lowest value, the display will read "SIMPLE
MODE".
In Simple Mode a set of control equations is used which usually requires minimal tuning of the system
to obtain acceptable performance. A well-tuned PI or PID controller will give smoother pressure control
and may be necessary to control unstable systems. When the controller is in Simple Mode, the only
parameters which affect the pressure control loop are psi SETPOINT, STARTUP RAMP, SHUTDOWN
RAMP and BOOST AMOUNT.
In PI control mode the analog signal from the pressure transducer is compared to the parameter psi
SETPOINT, which controls the motor speed to maintain constant pressure in the system. In this control
scheme, the error signal between the pressure transducer and the internal signal determined by the psi
SETPOINT value is multiplied by the PROPORTIONAL GAIN. This signal is then used to determine the
motor frequency. If the pressure transducer signal and the internal set-point value were the same, then
the motor speed would be zero. High PROPORTIONAL GAIN and INTEGRAL GAIN values give
smaller error in the pressure, but also make the system more susceptible to oscillation.
Additional adjustable parameters found in the Constant Pressure menu help to optimize the
performance of the system. The use of these parameters was discussed in the previous section. The
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