This was originally posted on APC forums on 8/30/2012
I bought a sine wave inverter 850W from a vendor in kolkata. The machine make a audible humming sound constantly when on giving backup. I have registered it for servicing twice but the service person comes and says it is a standard feature and so servicing or checking is done and the the humming sound continues. I am left in the scenario helpless I have another inverter from APC that does not make any such noise. I do not know why APC sells such defective sets and then let the consumer suffer. Such is the scenario that inspite of claiming noiseless operation it does give out substantial noise when compared with other inverters of microtek and sukam installed at my relatives place which does not give out sound. APC has certainly lost its Quality credibility. I am extremely disappointed that APC and its authorized vendor duped me into buying such an expensive inverter with noisy operation not stating the facts before purchase.