Very low frequency is also bad for electronics but to get to that level of low frequency with generator, the voltage level will be too poor for most appliances hence my focus on high frequency

@SmartDepot the mechanics have found a way to increase the voltage of the AVR so that the low frequency will give a normal voltage. I had an experience of a 1kva inverter i installed for a client, which charges with phcn but not with gen. The inverter is 50hz +/-2 and was rejecting the 42hz frequency of the gen. The gen voltage is normal 220v. The gen is newly serviced. I tried increasing the gen frequency to 50hz and i discover the voltage also increased to 270v. At this point, i told the client that the gen should be fixed properly if they want to use it to charge the inverter batteries. Most of appliances can use 50/60hz, so having a higher frequency in a 50hz power doesn't have much effect but lower frequency does.

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