[Electric engineering.] . b k below thecase. Annunciators may be obtained in almost any desired Fig. 10. §28 INTERIOR WIRING. 31 finish and for any number of drops. One type that haslately become very popular is the self-restoring annunciator. In the ordinaryinstrument the drops must always be putback after a call comes in. Sometimes this isnot done, and consequently one is at a loss toknow, when several are down, which buttonhas been pushed. Self-restoring annunci-ators are constructed so that when a buttonis pushed, its corresponding drop falls andremains down until the next call is sent in.
[Electric engineering.] . b k below thecase. Annunciators may be obtained in almost any desired Fig. 10. §28 INTERIOR WIRING. 31 finish and for any number of drops. One type that haslately become very popular is the self-restoring annunciator. In the ordinaryinstrument the drops must always be putback after a call comes in. Sometimes this isnot done, and consequently one is at a loss toknow, when several are down, which buttonhas been pushed. Self-restoring annunci-ators are constructed so that when a buttonis pushed, its corresponding drop falls andremains down until the next call is sent operates a magnet that moves therestoring device and resets the first annunciators are somewhatmore liable to get out of order than thesimple kind and some of them require morebattery power. They are, however, a greatconvenience, and are rapidly finding are wired up to the buttons in the sameway as an ordinary annunciator, as the restoring device iswholly within the annunciator RTTXSTNG BELL WIRE. 42. There are no regulations governing the insulationused on bell wire. That generally used is known as annun-ciator wire and is usually No. 16 or No. 18 B. & S. copper-covered, with two wrappings of cotton treated with wire is cheap, but it is not moisture-proof, and theinsulation does not adhere very firmly to the wire. How-ever, it will work satisfactorily if it is carefully put up andis run in a dry place. For really good work, weather-proofoffice should be used. The insulation on this wire isheavier than on the annunciator wire and adheres firmly;it is also damp-proof. If it is necessary to run bell wireswhere they will be exposed to considerable moisture, the bestplan is to use rubber-covered wire. The size of wire used is generally No. 16 or No. 18 B. & S 32 INTERIOR WIRING. 28 It will pay to use nothing smaller than No. 16, because thecost is very little more and the line resistance is therebyreduced. Also the b
Size: 902px × 2770px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookidelectricengi, bookyear1902
