CVRDE, Avadi, has designed and installed a New Test Rig for Testing of Rotary Based Junction (RBJ) under dynamic conditions. The RBJ is used in the tank to transfer DC power and control signals from the stationary hull to the rotating turret.

The RBJ test rig has a Drive System consisting of a DC motor with gear box to rotate the RBJ through a turn table arrangement with a varying speed of 3-50 rpm. The Data Acquisition System of the test rig is a PC-based system with ADC and add-on cards, which provide necessary interface to the computer bus.


Rotary Based Junction Facility
Rotary Based Junction Test Facility

The signal conditioners modify the milli-volt drop across the pins and rings, multiplexes the signals and sends it to the computer for processing. Custom built software has been incorporated to log the data from the RBJ for interpretation and analysis. The rig measures the electrical performance of the RBJ through the following tests:
• Continuity test between pins and rings
• Light duty voltage drop test for control signals
• Heavy duty voltage drop test for 700 A signal
• Insulation test between each pin & body, and
•Endurance test under dynamic conditions.

The hard copy output of the test is used to detect shortcomings of the RBJ and serves as a useful tool for fault analysis.


R Adm S Mohapatra, IN Director, Naval Science & Technological Laboratory (NSTL), Visakhapatnam inaugurated the newly established Acoustic Test Centre on 25 August 2003. This acoustic test centre will enable NSTL to become a premier institute to undertake research in the field of acoustics, design of low noise machinery and other vital parts required in the submarines and ships for underwater warfare.The centre consists of an Anechoic Room and a Reverberation Room. Both the rooms are designed on a room inside room pattern having an air gap of one meter between inner and outer walls including the floor.


R Adm Mohapatra inaugurating the Acoustic Test Centre
R Adm Mohapatra inaugurating
the AcousticTest Centre

To isolate noise due to heavy vehicular traffic from the nearby highway, 80 mm thick vermiculite blocks were used for the foundations. The inner rooms weighing 300 tones each are floating on heavy duty neoprene rubber pads developed by Rubber Technology Group at NSTL. A low-noise blower and ducting system has also been installed in the test center for providing air while working in these rooms; and for combustion of fuel in the engines while the test is conducted. Provision has also been made for supply of cooling water for the engines.

The anechoic room is designed to have adequate volume to test almost all ship board equipment in the required frequency range; large sound absorption to simulate free field conditions and is designed to have free field measurements even at low frequency down to 50 Hz. The reverberation room is designed in such a way that no two surfaces are parallel and all surfaces are coated with highly reflective epoxy paints. This achieves very good diffusive sound field within a fixed time.

The facilities are equipped with advanced analysis systems, software applications and hardware configurations. The hardware includes robotic microphone positioning system with 5 degrees of freedom. With this instrumentation and softwares, it is possible to carry out various acoustic measurements as per ISO standards to characterise acoustic machines and materials.