PROBING THE MYSTERIES OF THE INVERTER: PART II

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This situation can be further aggravated when aluminum wire is used instead of copper. Aluminum is a great deal less expensive than copper and it is readily available ... but-when you use it-it's necessary to compensate for the metal's higher resistance by upgrading your wire size by one.

Furthermore, aluminum is easily oxidized. Its bright luster is soon masked by a thin layer of aluminum "rust" . . . which happens to be a fairly effective insulator. When this film builds up between a connection and a wire, localized heating can be magnified.

However, a special electrical paste has been developed for aluminum wiring. The material contains minute particles of metal dust, which effectively conduct current while shielding the aluminum against oxidation. The paste is also very good at protecting copper, and it must be used wherever the two metals are joined.

-CIRCUIT PROTECTORS

Fuses should be placed in every hot line ... on both the AC and DC sides of the inverter. Contrary to popular belief, fuses were never intended to protect you from shock, the appliance from a short circuit, or the inverter from an overload. Rather, in the event of a problem, the fuse blows to prevent a fire from starting ... that is its sole purpose!

Of course, a fuse or circuit breaker on the AC side of the inverter may protect the expensive unit from an overload ... but there's no guarantee. Also, bear in mind that fuses and circuit breakers are not always interchangeable: There are AC and DC circuit breakers, and it's up to you to know which type you're using.

Be absolutely certain, too, that you place the fuse or circuit breaker in the hot line ... never install a fuse or breaker in the ground or return wire! And, for safety's sake, always disconnect the power when you're working on the system. Assume nothing ... turn it off first, and then check with a tester, just to be sure.

We have, over the course of these two articles, covered a lot of -information about inverters ... and by now you should be ready to put one to use safely and efficiently. Buying an inverter does involve a considerable investment. But when properly applied, such a device can allow you all the advantages of a DC alternative power system along with the convenience of AC electricity.

SYNCHRONOUS LINE-TIE INVERTERS

You may remember, from Part I of thisstudy, that there's a class of inverters thatpermit you to connect your homemade powerto the utility lines. Depending on the methodby which they're hooked up, these devices mayallow you to pump excess power into the utility grid (for which you'll be paid) and thenrecei ve electricity from the power company(for which you'll pay) when you run short.The balance between the two directions ofpower flow will mean a less expensive monthly bill ... or, perhaps, no bill at all!Installing a synchronous inverter, however,i . s not nearly as clear-cut as is wiring one ofthe static units discussed in the main article. Because the power company is the sole owner of the utility lines, and you are only given the right to use them, you must abide by utility rules. And the catch is, every such institution's rules are different!

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