Power generators come in different types based on fuel source (propane or diesel) and power output. They are generally not made for different purposes- they create electricity to power devices in the event standard electricity sources are unavailable.
A hydroelectric generator does not require much maintenance. If you build it right or if you purchase a decent generator, you should not have much problems.
There's is five different kind; Audio, Radio, Microwave, Logic and Arbitrary.
Any kind of magnet can be used in a generator or alternator to generate electricity, even an electromagnet (when these are used the generator or alternator is called self-excited). But for the highest efficiency it should be a kind of magnet with a very strong field (so that more lines of flux can cut the conductors in the generator's or alternator's coils).
A backup generator is a wonderful idea. Depending on the kind you have there are many different ways. I would suggest you check out YouTube and watch a how to video.
You can check good full service power generator in your local Sears store. They have different kind whatever you want, it could be portable, standby or solar and wind generator.
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A portable generator is suitable for most homes in a blackout, you can buy a small generator for around $200 and it should power most or your appliances and lights in the event of a power cut.
The power generator you buy depends on the amount of power you need to generate. On Walmart.com there are several generators listed with various capacities. Be aware of the safety precautions you will need to take when using your generator.
All depends on what MW of a generator its coupled with, assuming we are talking about "steam" or "gas" turbines. Otherwise, its relevant to the coupled generator.
A generator needs some kind of engine to drive it, it won't start by itself.
There are many types of generators, but I would recommend a Powerhouse portable gas powered generator for your bunker. They sell for $799 and are available at home depot stores or online.
The general term generator is usually applied to the kind of generator that produces electricity, or electric power.