The PMTS-30 automatic transfer switch is designed for use in RV's with 30 Amp AC service. When plugged into the shore power it will automatically provide AC power to all AC appliances. To operate your appliances from an on-board generator, simply start the generator and the PMTS-30 will (after 20-30 seconds) automatically transfer the electrical power to AC appliances. (The time delay of 20-30 seconds allows the generator voltage to stabilize.)