JFD KI40018AA, Operation And Maintenance Manual, Page: 15 / 110

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KI-OM-6768 R0 Chapter 1
1.3.5 Control System
The 24 VDC control circuit is used to control the contactors, relays, timer and the safety circuits in
the system. The contactors, controlled by switches mounted in the control panel door, switch the
high voltage to the heaters and the pump.
The temperature of the output fluid is regulated by dumping excess capacity thereby increasing the
flow rate of fluid through the heater tank and lowering the output temperature of the fluid outlet. The
amount of fluid dumped is controlled by an electronic controller that operates the actuator on the
control valve. The amount to which the valve is opened is determined by the controller based on
feedback received from the PT100 temperature probe mounted into the outlet manifold.
Several safety interlocks are incorporated into the control system which provide protection against
low fluid level in the heater tank, over-temperature and motor overload. The control circuit also
includes indication via LED’s and the controller display for operator feedback. The power and
control system wiring diagrams are detailed in the electrical schematics in Appendix C - page 43.
Refer to Table 1.2 and
Fig 1.2 below for the control panel layout and part identification.
Fig 1.2 Control Panel Layout
The following table identifies the major control components, and outlines their function within the
control circuit. (Refer to wiring diagrams in Appendix C -
for full wiring details).