A dairy operation in North Eastern USA produces several million “one time use” plastic coffee creamers per day. The operation includes forming the small individual cup cartons, filling them and then sealing them on a high speed packaging line.
The electrical utility supply is 480V via a medium voltage 12.5kV distribution line., however the site is subject to many storms in spring and summer and these cause recloser switches to operate on the local electrical utility network. The recloser operations can result in reduced voltage or, in extreme cases, complete loss of voltage from a momentary power outage lasting several seconds.
The voltage variations cause major disruptions to the high speed creamer line. When the line stops, product has to be scrapped, then equipment cleaned and sterilized before restarting. This can take several hours even though the drop in voltage may last for only a small fraction of a second.
The Omniverter Chosen Solution
The Dairy operation decided to install dedicated power protection to the high speed creamer line. They chose to use a combination of an AVC (Active Voltage Conditioner Standard) to eliminate voltage sags and an AVCRTS (Ride Through Storage) with 10 seconds of back-up, in order to correct the network generated momentary outages.
The AVC is an on-line device which corrects the voltage sags. It continuously monitors the voltage and corrects even minor variations within a fraction of a cycle. It provides a steady constant output voltage to the high speed form-fill-seal (FFS) machine.
The AVCRTS is an off line device which corrects complete outages of short duration. It consists of an inverter and electrical storage (e.g. batteries, or ultra capacitors) which can carry the full load for a predetermined amount of time. Based on analysis of site data, battery storage for 10 seconds was chosen as the storage medium.
Since installation the AVC device has corrected a large number of voltage sags and when a power outage or very deep sag is detected the AVCRTS comes into play. The AVCRTS disconnects the load from the utility supply via a static switch (Utility Disconnect), and at the same time supplies the load with energy from the battery storage via the inverter. The inverter converts the battery DC voltage to 3 phase AC. The change over occurs within a fraction of one cycle (<1/4 cycle) and allows the sensitive load to continue to operate without disruption.
When the utility voltage is restored to normal, the AVCRTS will synchronize the load with the utility supply, open the static switch and restore the load to normal operation,.
The dairy operation reports that multiple storms caused severe electrical problems and that in one case they experienced a power loss of some six seconds. The creamer high speed line continued working without incident during this event but other equipment in the dairy, not protected by the Omniverter AVCRTS, suffered a power interruption and stopped working.