The existing local control panel is switched to manual operation. The new DDC controller can send out pulse signal to start the chillers and chilled water pumps according to the time schedule. In addition, the users or plant operators are free to start and stop the chillers and chilled water pump any time. The control logic of the DDC controller is required to suit the control panel and the control panel is also required to be modified for the plant daily operation.
The circuit diagram is attached here as reference for our users.