Power cut effect on City-Lab refridgerators and freezers


This winter electrical power is in short supply in Europe. In Finland electric companies prepare to schedule power cuts area by area during times when electricity is in high demand. The scheduled power cuts will last between 1 and 2 hours. In late November the University of Helsinki held a briefing and estimated that in their premises the power outs would be limited to one hour in duration.

For us at City-Lab the cold-stored products are a concern. We decided to test the effect of a power out on an empty fridge-freezer unit. Our units are seldom empty and the cold products buffer the effect of a power cut. However, we wanted to chart the most extreme effect of a power shortage.

Below the results of our test are presented in image form. We used wireless temperature sensors (RuuviTag). As can be seen from the first row, an empty fridge will reach over 8 degrees Celsius in an hour and over 11 degrees in two hours. Fridge-stored products have usually been approved for storage in 2…8 degrees Celsius. A one-hour power cut does not pose a significant risk based on our test but a longer power shortage is a problem. Based on the test we have stored multiple cold packs in our fridges to keep the unit cool for longer.

On the second row the change in freezer temperature can be viewed. After two hours the freezer is still at -10 degrees Celsius. Most of the freezer-stored products we receive are approved for storage at -10 … -30°C. It therefore seems that short power cuts do not endanger the freezer products.



Image: Power-cut test on a fridge-freezer unit. The wireless sensors were left to stabilize in the unit before start of test. At the start and in the end the readings were confirmed with a traditional analog thermometer.  Lähtötilanne = starting point. 1 h ilman sähköä = after 1 hour power cut. 2 h ilman sähköä = after 2 hour power cut.

For us at City-Lab storing your research products is a top priority. We will continue to follow the information coming from the universities and power companies. We work hard to make sure that your products are unaffected by temperature shifts!

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