VICI ITC - Manual (Page 6)

1.3 Technical Description
A general knowledge of the ITC’s organization and operation is helpful to its
successful implementation. To facilitate understanding, three questions are posed:
1. What position does the ITC occupy in a thermal system?
2. How is the ITC organized to accomplish its task?
3. What is the most important aspect of the ITC’s organization?
These questions are answered by Sections 1.31, 1.32, and 1.33, respectively.
1.31 Thermal System Overview
Figure 1 depicts a generalized closed-loop control system. The system is termed
closed-loop since the controller bases its corrective actions on the actual status of
the controlled function. In an open-loop system, corrective actions are based on
anticipated status. Closed-loop systems are definitely preferable.
The system is comprised of:
•
Controlled Function. Water level, air pressure, etc.
•
Sensor. Appropriate to the function; level sensor, pressure transducer, etc.
•
Controller. Determines when corrective action is necessary, based on
information supplied by the sensor.
•
Correction Element. Means of adding water, increasing pressure, etc.
With slight modification, the diagram becomes appropriate to a thermal system
utilizing an ITC, as shown in Figure 2.
CONTROLLED
FUNCTION
CONTROLLER
CORRECTION
ELEMENT
SENSOR
Figure 1
HEATED
ZONE
THERMOCOUPLE HEATER
INSTRUMENTATION
TEMPERATURE
CONTROLLER
(ITC)
Figure 2
4