Beijer Electronics BFI-H2 V1.12 - Manual (Page 44)

User Guide Revision 1.12
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point). For dynamic systems which respond quickly, the value will need to be shorter. Slow response systems, such as temperature control
applications will require a correspondingly longer time setting.
P3-03 Differential Time Constant: Range 0.00 to 1.00, Default 0.00
The differential time constant is also a time based function, this time modifying the PID output based on changes in the Set-point. In most
applications, leaving the setting of P3-03 at zero will give good results.
The user has to adjust the PID control parameters (P-gain, I-gain and D-gain) in P3-01, P3-02 and P3-03 respectively to get the best
control performance. The values will vary dependent on system inertia and the time constant (rate of change) of the system being
controlled.
8.2.7. PID Sleep and Wake Functions
The drive can be programmed to disable its output when running in PID mode when the speed output to the motor falls below a programmed
value. This is referred to a Sleep or standby mode. Generally fan and pump applications perform little useful work at the lower end of the
speed range and the sleep function allows the drive to save energy during periods of low system efficiency by shutting off the output to the
motor. The level for sleep mode is programmed in parameter P3-14. A time period is also applied to the sleep function such that the sleep
function must remain below the value set in P3-14 for the period programmed in P2-27 (standby mode timer) before the sleep function is
activated. Sleep mode is disabled if P2-27 = 0.
Once the drive enters into sleep mode a separate wake up mode can be applied for the drive. The wake mode level is used to trigger the drive
returning out of sleep mode to normal operation. Setting different thresholds for the sleep and wake levels allows boundaries to be set that
stop the drive continuous entering in and out of sleep mode and the settings to be optimised to maximise efficiency. Wake up level is set in
parameter P3-13 – PID feedback wake up level and is set as a percentage of the feedback signal such that when the feedback signal reaches a
specified level the drive is triggered out of sleep mode and the PID controller re-enabled.
8.2.8. PID Boost Cycle on Sleep and Wake
The drive can be programmed to execute a pre-defined boost cycle on entering or exiting sleep mode. This feature could be used to boost
pump pressure prior to drive entering sleep mode so the drive is able to maintain sleep mode status for a greater period (prevent frequent
switching in and out of switch mode. The boost on wake could be used to execute a cycle that quickly returns the system to normal operating
status prior to entering back into PID control.
The pump wake up boost is enabled when the speed hold time on enable P6-11 is set to a value other than 0. P6-11 contains the time that the
drive will run the boost function on wake. The speed for the boost function on wake is set in preset speed 7 (P2-07). The timing diagram below
gives an example of the set-up and motion profile for the Boost on wake function.
The pump sleep boost is enabled when the speed hold time on disable P6-12 is set to a value other than 0. P6-12 contains the time that the
drive will run the boost function before entering sleep mode. The speed for the boost function on sleep is set in preset speed 8 (P2-08). The
timing diagram below gives an example of the set-up and motion profile for the Boost on sleep function.