. Elementary and dental radiography . :. I,*. A static niaclunc. practically a uni-dircctional one. It will he recalled thai the primary andsecondary currents of the transformer are both alternating. let us trace a current of electricity from theTnstallation. mains llirt ugh an induction c<iil and auxiliary ajipli- ance leading lo it. ( Iig. 17.)\\ iring fr(!m the mains to the coil should always he (\onc hy a C(^m-petent electrician. A wire of a given size will carry only a certain am-perage witlunit heating. If this amperage he exceeded greatly the wire i6 ELEMENTARY RADIOGRAPHY may be
. Elementary and dental radiography . :. I,*. A static niaclunc. practically a uni-dircctional one. It will he recalled thai the primary andsecondary currents of the transformer are both alternating. let us trace a current of electricity from theTnstallation. mains llirt ugh an induction c<iil and auxiliary ajipli- ance leading lo it. ( Iig. 17.)\\ iring fr(!m the mains to the coil should always he (\onc hy a C(^m-petent electrician. A wire of a given size will carry only a certain am-perage witlunit heating. If this amperage he exceeded greatly the wire i6 ELEMENTARY RADIOGRAPHY may become hot enough to set fire to surrounding building material of acombustible nature. There are, therefore, laws governing the size ofwires to be used to carry different amperages. Coils are rated by theirmanufacturers to consume a certain number of amperes, and wiring. Fig. 13. Induction or Ruhmkorff coil. should be done according to this rating. The amount of amperage neces-sary to operate a coil varies directly according to the size of the coil—the larger the coil the more amperes it takes. Assuming the coil to beof a medium large size, the lead wires used to connect it to the mainsshould be capable of carrying at least 30 amperes without heating. Bylead wires I mean the wires leading to the machine—not lead (themetal) wires. The wires are copper. • X-RAV MACHINES 17 Somewhere near where the wires enter thefll$($. building, and also at the coil itself, will be found fuses. (Iig. A fuse is a wire, an alloy oflead, of a given size, and fusing point capable of carrying only a limitedamperage without melting. Thus if more than 30 amperes be sentthrough a 30-ampere fuse, the wire is heated to its fusing point, it melts,the circuit is broken, and the flow of electricity is stopped. A fuse is a
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