ELECTRICAL TESTS A\D THEIR .tri'l.lC.tTIOXS .W 



III ortler to jjivo a general pirturo of tlio kinds of troiil>lo found wiili 

 this transmission tostinj; e(|uii)nK'nt tlu- followiiij; lal)lr shows a Irouhlt^- 

 classitication which is particularly useful in anaKv.in^ testing results 

 and instigatini; any riHiiiircd romedial iiHisuns. 



Classijicalion of Troubles Found 



Ph\sicai defects. Wroni; l\ pe of i>(|iiipiiU'Tit or 



Opens. circuit. 



(irounds. Missini; e<iiiipnienl. 



Crosses. High resistance. 



Cut Outs. Low insulation. 



Hlectrical <lefects. Wrong routing. 



Incorrect wiring. Bridged conductors. 



The above classification includes all of the common types of troubles 

 which, if not kept out of the plant, will be detrimental to service. 

 The item of physical defects is a class of trouble which is not de- 

 termined directly by transmission tests but is discovered by the 

 maintenance forces during the course of their testing work. It rep- 

 resents any unsatisfactory conditions found in the circuits which, 

 while not causing trouble at the time, may very likely do so later and 

 should, therefore, lie corrected. The next four kinds of trouble shown 

 in the table \iz: opens, grounds, crosses and cut-outs while detected 

 b%' transmission tests can also lie found and cleared by the every- 

 day maintenance work without the use of transmission testing ap- 

 paratus. The remaining classes of trouble listed can, it has been founii, 

 be detected and eliminated most efficiently by the use of transmission 

 testing sets. Classifying troubles and identifying them with the 

 important circuits in the exchange area plant such as cord circuits, 

 operators' circuits, trunks, etc., has proved very valuable in trans- 

 mission maintenance work. The results of the work when analyzed 

 in this way are a very great aid in supervision and assist materially 

 in keeping the plant in good condition. 



The visual reading circuit of Fig. 2't is also designed in a form 

 for (x-rmanent installation particularly for use in testing toll circuits. 

 .\ picture of a t>pical installation of one of the latest t>'pes of sets 

 and its as.sociated oscillator is shown in Fig. 27. 



From 40 to rtO instruments of the general type shown in tlu- picture 

 are now located at important toll centers throughout the country. 

 They are constantly used to check the overall transmission efficiency 



