A baby cow is called a calf. Adult male cows are called bulls. Adult female cows are called heifers until they give birth; after they have given birth, they are called cows.
As long as there is a fuel supply of natural gas or propane, a well-maintained backup generator will keep running. If the Generac generator is running on propane, with a 500-gallon tank, it should run 24 hours a day for over a week. How loud are they? Generac generators are very quiet.
A electricity generator is like the reverse of an electric motor ..where the generator produces electricity, a motor uses it. A 'Genset' is a combined unit consisting of a generator and a driver. A small unit will probably have a diesel or gasoline driver (engine) connected directly to the generator in a compact unit. A fuel tank will be included. In large industrial models, the unit is mounted on a 'skid' which can be moved if required.