Published: 27 May 2011
Category: Q&A
Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This Question of the Day, concerning a 110V 2kVA transformer feeding a handryer, is answered by the ECA:
Question: Whilst recently working on a 110V 2kVA transformer feeding a handryer, I found the voltages on L1 and L2 to differ from each other. L1 had 44V to earth and L2, 66V. This obviously is wrong.
I managed to balance the voltages by cross bonding the independent earths to the main earth for the transformer.
Could you tell me why the un-balance on the voltages occurred, and why cross bonding the earths worked?
Answer: It sounds as though the secondary winding mid-point had no connection to earth, leaving the secondary voltage floating and variable. Connecting the mid-point to earth gave the transformer secondary winding a fixed earth reference.
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