Battery Tripping Unit for Space Constrained Substation Container Applications

Abstract

Protecting power and distribution equipment from major faults will aid in preventing infrastructure damage and unnecessary power supply losses. Battery operated tripping units are used to open (trip) or re-close HT breakers in a substation during power supply failures. Short bursts of high currents from a battery bank in the substation switch room is used to energize open and close coils of HT breakers. A proposed 30 V, 10 A charger with an adequate battery bank can be an ideal sized unit for HT breaker tripping applications in a space constrained substation container (750 mm x570 mm x280 mm), placed in remote areas. To ensure easy unit access and serviceability, the batteries, control system and battery charger power module are all integrated into a single enclosed mountable cabinet unit. The dimensions and mass of the proposed housing cabinet was minimized to optimize space utilization and easy mobility. The housing cabinet can then be wall mounted or even placed on the floor, allowing it to be easily moved in the substation from one location to another. The PC board is also conformal coated to protect against corrosion due to humidity and a properly designed solder mask avoids unintentional short circuits. The battery charger makes use of a thyristor controlled full-wave bridge rectifier to charge the battery bank and will also include appropriate diagnostic faultfinding warning alarms. The proposed 30 V, 10 A battery charger system addresses some shortcomings of current battery charger implementations at remote substations, especially when the system is required to operate at higher ambient temperatures. This proposed battery charger system makes it possible to use up to 25 nickel cadmium cells or 15 lead acid cells to continuously supply 30 V at 10 A for fast charging and/or standing loads or both. In addition, several features have been added to assist technicians in determining potential battery charger faults in order to reduce breakdown times.