Cyclopedia of applied electricity : a general reference work on direct-current generators and motors, storage batteries, electrochemistry, welding, electric wiring, meters, electric lighting, electric railways, power stations, switchboards, power transmission, alternating-current machinery, telegraphy, etc. . of the maintenance expense of electricalequipment of cars. Almost all repair shops have men continuallyemployed in repairing them. The most frequent trouble with arma-tures is through failure of the insulation of the coils and consequentgrounding. This term is used in connection with arma
Cyclopedia of applied electricity : a general reference work on direct-current generators and motors, storage batteries, electrochemistry, welding, electric wiring, meters, electric lighting, electric railways, power stations, switchboards, power transmission, alternating-current machinery, telegraphy, etc. . of the maintenance expense of electricalequipment of cars. Almost all repair shops have men continuallyemployed in repairing them. The most frequent trouble with arma-tures is through failure of the insulation of the coils and consequentgrounding. This term is used in connection with armatures andfields and other electrical apparatus where a direct path exists toground. As the armature core is electrically connected to the groundthrough its bearings and the motor casing, a break-down of theinsulation of the coils in the slots permits the current to pass directlyto ground. This shunts the current around the fields and an abnormalcurrent flows because of their weakness. The circuit breaker or fuseis placed in circuit to protect the apparatus in such an emergency,but usually before such devices break the circuit, several of the coilsof the armature are burned in such a manner as to make their removalnecessary. The coils are so wound on top of one another that in 248 ELECTRIC RAILWAYS 153. Fifi 136. Diagram Showing the Effect of anOpen-Circuit in Armature Winding order to replace one coil alone, one-fourth of the coils of the arma-ture must be lifted. With the armature ofNo. 1 motor grounded the carwill not operate and if theresistance points be passedover, the fuse will usuallyblow. When No. 2 motoris grounded the action ofNo. 1 motor is not impairedand this latter motor willpull the car until the con-troller is thrown to the mul-tiple position. But if themotors are thrown in multi-ple, the path through theground of No. 2 motor shuntsmotor No. 1. Next to grounding, open-circuits are the most serious defectsof armatures. These are usually caused by burning in two o
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Keywords: ., bookauthoramericantechnicalsoci, bookcentury1900, bookdecade1910
