Chiller Controls

Built a control package to control two 30 ton refrigeration units on falling film chiller system. System includes flow interlocks, startup and shut down delays, and an HMI to allow the control setpoints to be changed and the process temperaures to be trended. The system also controls two pumps, one of which is on a variable speed control to control the water level in the systems sump.

The system was implemented using a small PLC and hmi and cost less than $500 including the RTD input card and RTDs. The system reused the enclosure and power supply from the previous control package. The new controls increase reliability and ease of use: they interlock water flow ith the refrigeration system ensure that the refrigeration system does not operate without a load, pumps down fully before the load is removed, and adds temperature setpoint control to allow the refrigeration system to shut down when the operating conditions allow it.