Electronic relay developments

NEW ADVANCES in electronics, accelerated by the recent war, offer many applications in addition to their use for military, aviation, or communication purposes. Heretofore, the use of electronic circuits in relaying schemes has been mainly to supplement the more conventional electromagnetic schemes. Examples are the use of carrier current in a pilot directional scheme and auxiliary electronic relays for timing. The purpose of the development work described here has been twofold — firstly, to apply the newer techniques to the fullest advantage and secondly, to employ electronic circuits so that they will perform complete relaying functions in themselves. The advantages offered by these new electronic relay circuits compared with electromagnetic or prior electronic types are: 1. The number of moving parts and contacts has been reduced to an absolute minimum by having all functions of fault detection, determination of direction and distance, insertion of intentional time delays, and so on, performed by the electronic elements. 2. The circuits are constructed of standard electronic parts. 3. A high degree of accuracy is obtainable in the determination of overcurrents, the measurement of distances to faults, and in the insertion of intentional time delays. 4. The sensitivity of the vacuum-tube elements provides fast action even with very low control voltages. 5. There are a minimum of magnetic parts, eliminating errors due to saturation. 6. All vacuum-tube circuits place very light loads on the tubes with a minimum of tube types involved.