Once the elevator in the Danish dairy's cheese drying system fails, the entire plant will be shut down, with an hourly loss of about 5 tons of cheese (the total loss due to a single failure is about £40,000). Vendors estimate that this situation will take about two weeks to recover. Because of the downtime, engineers had to transfer the semi-finished cheese in the warehouse to other warehouses, and the cost of storage and transportation increased over time. “The programs we used to use are constantly experiencing various problems,†Mr. Hansen explained. "The previous program didn't allow us to adjust ourselves. Just to solve the various problems that occurred, we had already spent about 80,000 krona (8,000 pounds). Finally, one day, Emerson CT solved the headache for all manufacturers. But this is still a temporary solution, so we asked Emerson CT to provide us with a better permanent solution."
“Because we have used Emerson CT's drive system elsewhere in the factory and know about its excellent performance, I immediately got in touch with Emerson CT's drive center after the above failure. Engineers installed their elevator software for us, and the system was re-running that day,†said Per Hansen, chief electrical engineer at Danish MD Food Rødkærsbro Dairy.
A few months later, Emerson CT Denmark established a new elevator control system based on the full control of the existing PLC controller, using Unidrive AC drive system and Unimotor servo motor. In this new system, each Unidrive drive system operating in servo mode is equipped with a unique Emerson CT plug-in application module. Emerson CT's software engineers worked with PLC controller vendors to rewrite the positioning software.
The instructions in the new software are all from the PLC, but all the positioning is implemented by the software in the application module that comes with the Unidrive drive system, thus avoiding any post-operation problems.
During the production process, the elevator is mainly responsible for feeding 200 grams of cheese per pack into a 21-grade cheese dryer and sending it out. Both the feta and the cheese bag need to be cooled and dried in a long tunnel before being sent to the packaging department. The specific procedure is to first select the drying level for each package of cheese by the PLC, and then the Unidrive servo system is responsible for moving the elevator adjacent to the selected path and then pneumatically feeding it to a conveyor belt running at a low speed.
The feedback in this series comes from the shaft mounted encoder on the Unimotor brushless servo motor.
“The new system is now faster and more accurate,†says Per Hansen. “And, the most important thing is more reliable. Reliability is the number one priority in this type of production equipment,†he continued. “Every week I report the factory’s production loss per minute and what remedies I will take. That’s why I chose to use Emerson’s drive system – because its local drive center provides comprehensive support, since It was the case when it was established in 1989.
The first drive system we used was a 7.5 kW Commander CD drive system for pumps in new water treatment plants, and their AC drive systems have been used ever since. Of course, we have tried to use other drive systems during this period, but practice has proved that this is the most wrong choice! Now we mainly use 100% AC drive system, because the whole factory is wet and corrosive gas, and all the motors must be sealed, so for hygienic reasons, we need to use high pressure water and steam to continuously wash, This requires a 100% AC drive system to complete. â€
In fact, the Unidrives drive system works in many places, "but we basically only use it in dryers," says Mr. Hansen, "because it makes our maintenance work easier and faster. And when I need to replace it When you drive the system, you only need to insert the module without resetting the parameters, and the system will work as it is. Even if it only saves 5 minutes, I think it is a valuable investment."
“The factory has been very busy,†Mr. Hansen concluded. “Any stoppage can cause huge economic losses. So we use Emerson CT's drive system to maintain production continuity and thus reduce unnecessary losses. Choose Emerson CT's drive Products, you will kill two birds!"