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sleep. 1.4.6 FORCE SLEEP THRESHOLD is additional system protection in analog CP. This is a value
(entered) + the 1.4.1 ANALOG SETPOINT 1.
For example, the default value for 1.4.6 FORCE SLEEP THRESHOLD is 20 psi. If the 1.4.1 ANALOG
SETPOINT 1 is 50 psi, the drive will stop if pressure reaches 70 psi.
Similarly, 1.4.5 SLEEP FREQUENCY can be used to put the drive to sleep. 1.4.5 SLEEP FREQUENCY is
defined as a value (entered) + 1.1.1 MIN FREQUENCY. As constant pressure is achieved and the drive slows
down, the unit will go to sleep when 1.4.5 SLEEP FREQUENCY is achieved. It is recommended that 1.4.7
WAKE UP THRESHOLD and 1.4.5 SLEEP FREQUENCY values be entered after observing the system.
ON/OFF Cycle Timers
The controls also record the length of time the motor remained in the OFF cycle and compare that time to the
parameter, 1.4.23 T OFF. If the motor-off time during the last OFF cycle was greater than the value of 1.4.23
T OFF , then the minimum motor-on time will be equal to 1.4.23 T1 ON. If the motor-off time was less than
1.4.23 T OFF , the minimum motor-on time will be equal to 1.4.24 T2 ON.
In other words, the time of the last OFF cycle determines whether the next ON cycle should be relatively long
or relatively short. Figure 20 demonstrates how the system adjusts the motor-on time in response to motor-
off time.
Figure 20 – Motor On and Motor Off Times
Fine Tuning with PI Control
The stability of the constant pressure system (i.e., its tendency not to exhibit pressure oscillations) is
determined by parameters set on the keypad, the flow rate of the pump, and the volume of the pressure tank.
Stability of a system with a large maximum flow rate and a small pressure tank will be more difficult to control
and may require de-tuning the system to accept larger variations in the system pressure and longer response
times.
Pressure control is achieved by adjusting the values of 1.7.4 ProPORTIONAL GAIN and 1.7.3 IntEGRAL
GAIN. Larger values for 1.7.4 ProPORTIONAL GAIN and 1.7.3 IntEGRAL GAIN give smaller error in the
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