41
VLT
®
Series 3500
Example 7:
In a pump system, a constant pressure of 5 PSI is to be
maintained. The integrated PID controller in VLT Series
3500 is used. Normal regulation is desired, in which the
speed is reduced when the pressure increases and vice
versa.
The following must be programmed:
Function Parameter # Parameter Value Data Value #
Safety interlock 003 KEY HOA w. stp [1]
Activation of PID-regulator 101 CLOSED LOOP [2]
Feedback type 114 CURRENT [1]
Regulator range 120 Application dependent
Proportional gain 121 Application dependent
Integration time 122 Application dependent
Minimum speed 201 10 Hz
Maximum speed 202 60 Hz
Internal setpoint 205 50%
Current signal 413 4 to 20 mA [2]
The transmitter used is a 4 to 20 mA, 0 to 10 PSI type.
Since a pressure of 5 PSI is required, this corresponds to
50% of the working range of the transmitter, which in turn
corresponds to the setpoint programmed as the internal
setpoint in the drive. (Digital reference = 50%). The
minimum speed must be 10 Hz and the maximum speed
60 Hz.
NOTE:
A shield for control wires is to be connected in
accordance with the installation instructions.
All settings are based on factory settings.
Be sure to check the motor data settings (parameters
104, 105 and 107, or the Quick Setup menu items 1, 2
and 3). They must be set based upon the actual motor
used.
1 = Start/Stop
2 = Feedback pressure transmitter 4 to 20 mA, 0 to 10
PSI
External safety interlocks can be connected between
terminals 12 and 27.
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