Completion Date: July 09

Project Brief:

Replace the existing manual control panels, and integrate all wiring into the existing SCADA / PLC control system. Change the system over, while maintaining refrigeration capability and room temperatures

Electrical Content:

• Investigate, document, and label the existing wiring, and systematically change each of 9 compressors and their associated equipment over to the PLC control system which we installed a couple of years ago. The PLC needed expansion to cater for the increased I/O count. 

• All control equipment was 230v, so wherever possible we separated the wiring and changed the control voltage to 24v DC. 

• The biggest problem was keeping the old system functional, while changing over to the new system. The high stage / low stage interlocks had to be duplicated, and temporary wiring put in place to facilitate this.

Programming / Functionality:

• The duty cycling of the compressor sets can now be changed on the run.
• The room controls have better functionality with the defrosts being the major beneficiary.
• Alarms are generated for any motor start failures, or compressor safety trips, or room over-temperatures
• Events are logged and analog signals are trended, and as such any problems can be quickly tracked and rectified.
• An inexperienced operator can now follow and run the system with very little training, and minimal refrigeration knowledge.
• Password access allows a greater depth of control for more experienced people, and all setpoints are now readily accessable to those that are allowed.
• All communications are Ethernet IP, and therefore the SCADA can be relocated to anywhere within the plant, or duplicated effortlessly.
• Remote access and monitoring allows an alarm to be quickly diagnosed and possibly rectified.

Client Feedback                  

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