Marathon Monitors Inc.
Three types of Proportional control are:
1.Time-Proportioning: Referring to the modulation of the duty cycle. That is, changing the ratio of On Time versus Off Time in systems that use such devices as heating elements, electronically operated/assisted valves, or servo drives that use analog command signals for control.
2.Position-Proportioning: Referring to the adjustment of a variable positioning device such as a positioning motor with slidewire feedback.
3.Voltage or Current Output Proportioning: An Analog output's (voltage or current) amplitude is varied based on input from rheostats, thermocouples, ammeters, etc. to control heat applications.
The UNIPRO provides many ways to use the above control methods. Setup has details for setting the Control Modes to determine the method to be used. Some typical applications for the Proportioning method are:
1.HIGH/LOW or HEAT COOL heat application system: Set Control Modes for Time-Proportioning. This provides that CONTROL OUTPUT #1 (TBA-7, TBB-7) and CONTROL OUTPUT #2 (TBA-8, TBB-8) are in opposite conditions at either extreme of the control range and are both OFF at the midpoint of the control range.
2.ANALOG OUTPUT control: Set Control Modes for Time-Proportioning. This provides a 0 to 5 VDC or 4 to 20 mA output which is selectable on the ANALOG OUTPUT BOARD (TBD-13 through TBD-16, see Section 2.14 and Section 8.0 for
Unipro 3.5 Process Control | 1 Aug. 1997 |
