SILVER FERNS FARMS: PAEROA REFRIGERATION AND PLANT CONTROLS
Completion Date: July 09
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
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.
Silver Fern Farms Waikato region plants have been utilising EPIC Systems for a number of years for both electrical maintenance & capital work.
EPIC have been involved in numerous projects and as such were ideally positioned to take on the Paeroa refrigeration upgrade.
Initial plans were to change over systems during planned downtime however production requirements changed mid project.
This meant that the plant changeover had to be implemented whilst on line. Epic successfully met this challenge keeping the plant operational and commissioning the new system without interruption to operations.
Silver Fern Farms Ltd