Magazine article American Cinematographer

Cinema Workshop

Magazine article American Cinematographer

Cinema Workshop

Article excerpt

ELECTRIC CURRENTS IN FOREIGN COUNTRIES

Location shooting is the new name of the game and crews find themselves hopping from one country to another. Foreign travel can cause many problems for a film crew. In addition to frequent trips to the bathroom, the crew will also have to make several trips to the local hardware or electrical store to obtain various adaptor plugs and step-down/up transformers. There is a wide variety of electrical currents in use throughout the world; if you plug into the wrong type you may destroy or damage some expensive equipment, or be out of sync.

One should first be aware of the various ways in which electrical currents can differ. The most basic difference is the type of current: Alternating Current (A.C.) or Direct Current (D.C.). Almost all countries are now A.C., which is good, since most electrical devices are designed for A.C. operation. There are a handful of cities around the world that still offer D.C. However, this is almost always in conjunction with A.C. service and the two types are usually clearly marked.

Once it has been established that current is A.C., the frequency of the current must be determined. There are two frequencies in common use, 50Hz, (Fifty Hertz) and 60 Hz (Sixty Hertz). The 60Hz frequency is used in North America and parts of Central and South America. It is also used in Taiwan and can be found in some other countries, along with 50Hz. The 50Hz frequency is used in most other parts of the world (Europe, Asia, etc.).

The difference between 50Hz and 60Hz will have little effect on most applications, with the exception of sync motors and resolving systems. A sync motor relies on the frequency of the A. C: power for its speed accuracy. If a 60Hz sync motor is plugged into a 50Hz line, the motor will run 1/6 or about 17% slow, no matter what the voltage is. Likewise, a 50Hz motor plugged into a 60Hz line will run 20% fast, even at the proper voltage. If a pilotone system is employed, using sync motors and taking the pilot frequency from the mains, the track must be transferred (resolved) using the same frequency. All these problems can, of course, be eliminated by using governor motors and sync cables, or, better yet, crystal sync. …

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