# The Model Engineer and Amateur Electrician; A Journal of Mechanics and Electricity for Amateurs and Students Volume . 4

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## Description

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1901 edition. Excerpt: ...to me as 8 amperes 50 volts output, and is connected in shunt, and has been running well up to 45 volts, with six i6 Ediswan lamps on, at somewhere between i,800 to 2000 revolutions. Seeing that we were under the voltage wanted, I have had larger pulley on engine, and she runs now about one-third faster than before; and now the difficulty comes in, for she will not excite in the least, which is, to say the least of it, most annoying. I have examined every connection, and tested both fields and armature for insulation; and everything, so far as I can see, is alright. 1 might say I have reversed fields since I bought the machine, but she has gone alright many times since then. There seems just as much spark under brushes when fields are disconnected as when connected. The dynamo is fairly well proportioned, and quantities of wire, as near as I can tell, as follows: 65 x i0 turns, average i6 ins. on each field = 580 yards No. 20 on fields; armature, 6 coils of 84 turns average i2 ins. active No. 22 s.c.c. Armature Is 7 ins. by 3H ins. over all. Can you say what the output should be at say 2000 revolutions? The resistance of the field winding (i,740 ft. of No. 20) is about i4 ohms, and with a voltage of 45 there would be 3 amperes used in the shunt coils and the six i6 c.-p. 50 volt lamps would take about 7 amperes, which, added to the current in shunt, brings the total up to i0 amperes to be carried by the armature winding. This is nearly twice the amount it will carry without warming up, so that it is probable that the insulation has given way or the armature is partially burnt ouL The output should not exceed 3 or 4 amperes at volts. A dynamo that has had its fields reversed is liable to lose its, residual magnetism and fail to excite. Try...show more

## Product details

• Paperback | 222 pages
• 189 x 246 x 12mm | 404g
• Miami Fl, United States
• English
• black & white illustrations
• 1236577833
• 9781236577832