PSLV-D2-Grounding scheme and EMC considerations

Summary form only given. The PSLV-D2 vehicle consists of 14 subassemblies in which the various avionics packages and control systems are located. The return circuit configuration for interfacing of the various avionics system is very important to achieve the required accuracy in measurements as well as to have a EMI free system. The avionics system on the PSLV-D2 can be categorised into: navigation, guidance and control system; instrumentation and telemetry system; pyro system; power system. The stringent accuracy requirement imposed on the navigation system to meet final orbit accuracy calls for a well designed grounding scheme. The maximum rise in ground potential allowed is only 20 micro volt, in the presence of PWM operated high power control actuators, 3 RF transmitters and a host of DC-DC convertors. The PSLV-D2 instrumentation system employs a total of 450 low level output transducers and ensures that the performance of the measurement system in the launch vehicle EMI environments poses a major challenge to the electrical integration team. The grounding scheme for any satellite launch vehicle system has to address the following: vehicle powering scheme; interface scheme between various avionics system considering ground loop formation and EMI aspects; shield termination scheme; static charge build up-protection. This article briefly presents the PSLV-D2 vehicle avionics system and the grounding scheme philosophy. Also during the development phase certain problems were noticed with regard to noise in critical lines, and rise in ground potential. The solutions attempted are highlighted