Transfer relay will not cause a power surge to "smoke" any appliance. Odds are the Genset was either not at correct speed or it has a Voltage regulating problem. Possible voltage regulator if your Genset has one. SPEED (1800 RPMs) is 128 volts no load. If the Genset runs faster than 1800 the 120 voltage increases also. If someone turned the idle screw in to stop a Onan Genset from surging or running rough, that will INCREASE the engine speed and the AC voltage. Doug
Really need Year of RV and Model of Onan