RV generators come in three variations; horizontal, vertical and Permanent Magnet (inverter type generators). We will cover the variations in separate blog/s so this one will only cover basic electrical generation.
Generator 1 (not even 101). If you take a magnet and wiggle it close to a copper wire, you will produce electricity. Not much, but some. To make a lot of electricity, manufacturers put a bunch of wires together (multi-coil stators) and make very strong variable magnets (wound rotors). They place them in housings and make an engine turn the rotor.
Let’s get our magnet (rotor) set up first. If you cut out a bunch of some special sheet metal in the shape of a Roman numeral I and glue them together, you will have a magnetic core. Drill a hole in the middle and attach a shaft to connect to the engine and you have a rotor core. Put a coil of copper wire on each end of the I, one wound clockwise and one counterclockwise. Connect the coils together on one end and run the other ends to the shaft and install a set of slip rings so graphite brushes can bring in a variable dc voltage and amperage. Presto, you have a two pole rotor that has a north magnetic pole on one coil end and a south magnetic pole on the other. This rotor has to turn at 3600 rpm to make 60 Hertz electricity. If you add two more coils, you will have a four magnetic pole rotor that only has to spin at 1800 rpm to make 60 Hertz electricity. Simple, isn’t it.
Now let’s get the stationary coils (stator) set up. Let’s cut up and glue more of the special sheet metal into a ring shape pattern with two projections on the inside. If we install copper wire coils on the projections we have a rough stator. Connect two of the ends of the coils together and bring the other two wires out to the generator circuit breaker (the black wire) and the neutral connection (the white wire). Connect a green wire to the sheet metal of the stator to make the breaker trip if something goes bad rather than fry your fingers (or other body parts).
Press this ‘stator’ into a housing, put the rotor inside it, connect an engine at one end of the rotor and a ball bearing with the slip rings at the back end and we have a basic generator.
As the rotor turns, the magnetic north and south poles induce electricity into the stator coils. The sheet metal pieces aid in concentrating the magnetic fields to make the process more efficient. Alternating current electricity is sort of a push pull operation. As the first (positive) coil pushes voltage out the output cables, the second (negative) coil sort of sucks it back in on the neutral side of the circuit. When the rotor goes a half turn, the process reverses itself and we have alternating current electricity.
The stator has some other coils on it to help make the unit complete. We need to control the voltage level so we need a power supply for the voltage regulator. Onan calls their power supply Quadrature coils (Q1 and Q2). Generac calls theirs Displaced Phase Excitation (DPE) coils. This is so the non-engineer rest of us won’t know what their talking about and they can charge more for the generators. The stators also have small coils that power the 12 volt control boards with maybe a little left over to slooowly charge a battery.
If you think you know enough about generators now, please remember the two basic rules about electricity. 1. Don’t play with the pretty copper things. 2. Electricity, in large doses, does not take prisoners. Talk to you next week, if I’m not out camping.
Generator Jim