Saving a System w/ a Buck and Boost

The unit in this video is particularly susceptible to overvoltage conditions. Catastrophic board failure can result from voltages over 253, and the ICM493 shows that we indeed have an overvoltage condition. Since the power company won’t do anything about the issue, we decide to use a buck and boost transformer to drop the voltage BEFORE the ICM493. Buck and boost transformers can either boost (increase) the voltage or buck (decrease) the voltage.

First, we shut off power and confirm that it’s off by testing the power to known voltage sources. The transformer we are using is rated for 0.750 KVA, meaning that we have a 750VA transformer. We have to read the specs and the manual to make sure that we wire the transformer properly. The manufacturer literature has a chart that tells us how we can buck the voltage from 250-255 volts to a more acceptable level; the chart cell corresponds to a wiring diagram tailored to our needs. The connectors are labeled and will correspond to the labeling on the diagram.

We test the voltage before connecting it to the unit. The primary voltage is 252.5, but the ICM493 reads about 235 volts, meaning that the buck and boost transformer has bucked the voltage and is working as intended. When the unit is attached, the line voltage is only 237, which is much closer to the rated voltage than 253+ and gives us a lot more tolerance both ways.