32
Operating Instructions – MOVITRAC® LT Option Cards
8
Operation
PI Controller
8.5.2 Potentiometer 2 (POT2): Reference voltage preset
For those applications that require a fixed preset operating point, an on-board preset
potentiometer (POT2) is available to avoid having to use an external potentiometer for
this type of application. To use this feature, S4 must be open (Off).
The preset voltage ranges from 0 V (fully counterclockwise) to 10 V (fully clockwise).
The preset voltage can be measured on the PI Option test point .
8.5.3 Integral gain switch
The integral gain value can be set using switches S1 and S2 on the board. The time can
be set in 3 steps (0.1 s, 1 s and 10 s). The greater integral time will take precedence if
S1 and S2 are closed at the same time.
TIP
• If an external reference is used (either voltage or current format), this potentiometer
must be turned to zero (fully counterclockwise). If this is not done, an offset will be
introduced by POT2.
• When the 4 – 20 mA setting is used for either the feedback (pin 7) or reference
(pin 6) input and the 0 – 10 V setting is used for the other input (e.g. 0 – 10 V ref,
4 – 20 mA feedback), the voltages measured on pins 6 and 7 will be different under
stable operating conditions. This is due to an offset of 2.5 V, which is introduced
internally to support 4 – 20 mA operation. Control settles with the 0 – 10 V input
nominally 2.5 V lower than the 4 – 20 mA input.
• Both potentiometers 1 and 2 are 5-turn types, i.e. they require 5 full turns to cover
the full range. In the event of the maximum or minimum point being reached, the
adjustment disengages to avoid mechanical damage. The factory setting of both
POT 1 and 2 is the minimum value (turned fully counterclockwise).
Switch no. Switch open (OFF) Switch closed (ON)
S1 Integral gain 0.1 s Integral gain 1 s
S2 Integral gain 0.1 s Integral gain 10 s
S3 Feedback format 0 – 10 V Feedback format 4 – 20 mA
S4 Reference format 0 – 10 V Reference format 4 – 20 mA
TIP
Parameter P-16 must be set to voltage mode (0 – 10 V) to support the PI controller.
Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: info@clrwtr.com
To Next Page
Loading...