An OLTC, on-load tap changer, selects different taps on a transformer winding while load current flows, using a diverter switch with transition resistors or reactors so the circuit is never broken. Typical ranges give plus or minus 10 to 15 percent in steps of about 1.25 to 1.5 percent. An automatic voltage control relay drives it to hold busbar voltage within a bandwidth. Tap changers are the most maintenance-hungry part of a power transformer, with contacts and oil inspected after a set number of operations.
OLTC on T2 is stuck on tap 13 and the bus is running high, put it in manual and drop two taps.
Also heard as
- on-load tap changer
- load tap changer
- LTC
Related terms
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