No abstract

Wire and cables are demanded to have not only high reliability in electrical and mechanical properties, but also low disaster characteristics from the viewpoint ofjre safety. For this purpose, we have supplied low smoke, halogen free, flame retardant cables called "Clean Cable" since 1983. From the viewpoint of environmental protection, we have developed a new type of halogen free recyclable cable with low toxic gas emission. Our new recyclable cable's material is low density (d=l.l), halogen free, and flame retardant material. By means of density difference, separation of the new material and PVC can be carried out easily with water flow on waste treatment.

No abstract

The method for measuring insulation resistance by superimposing the dc voltage has potential for detecting the deterioration of cable insulations. The deterioration of cable insulations can be detected by measuring current which flows through a grounded shielding wire. However, the earth current also flows from the cable sheath into the grounding wire as noise. Thus, to assess the deterioration properly, it is necessary to separate the earth current from the total current. On the other hand, to improve detection sensitivity, it is desirable to superimpose the highest possible dc voltage. In this case, provision must be made so that there are no adverse effects on the GPT.(2) Even if 5 0 4 dc is superimposed through the GPT, it is possible to prevent the magnetic saturation of GPT if the current injected by such superimposition is limited l(i.e., below max. 5 mA).(3) In lieu of a variable resistor, a variable dc voltage supply is employed in the bridge. The variable dc voltage supply requires no mechanically driven part, thus making it possible to realize a fully automatic monitoring system.