Vibration Laboratory

Vibration Laboratory has got unique facilities and expertise in testing and evaluation of transmission line accessories like conductors, insulator strings, vibration dampers, and spacer dampers etc up to 1200 kV as per national and international standards.

This laboratory has a test rig with a clear span of 40 m to carry out the damper efficiency test on single conductor/earth wire. The vibration laboratory of CPRI has been accredited by NABL on the basis of its compliance to ISO/IEC: 17025:2017 in the field of mechanical testing. Vibration laboratory is open for commercial testing and certification of various types of vibration dampers and other transmission line accessories. (Fig no:1)

Vibration in transmission line conductors are known to cause breakage of conductors. Mechanical failures of insulator strings are also observed in transmission lines. CPRI has a well-equipped vibration laboratory for studying vibration problems with forced excitation systems. The Institute has carried out extensive investigations in this field and successfully developed methods to effectively damp the vibrations. These methods relate to such aspects as location of dampers, self-damping of conductors, passive damping methods etc.(Fig no:2)

New Wake Simulation lab

The New wake simulation laboratory has been established to undertake R&D and testing activities on bundle conductors, spacer dampers and other transmission line accessories. This is a unique facility in the country for testing of bundle conductors up to 1200kv.This laboratory has a test rig with a clear span of 80m confirming to IS, IEEE, and IEC standards. It has suitable anchorages to string bundle conductors to appropriate tensions and also has all facilities for conducting tests on spacer dampers, bundle conductors, line accessories etc. Fatigue/Vibration testing of single, double, triple & quadruple insulator strings (both suspension & tension type) is undertaken.(Fig no:3 & 4)

Creep Test Facility

The creep test facility has been established in the Mechanical Engineering Division. The laboratory test will be carried out on the transmission line conductors complying with the requirements of      IEC 61395 – ‘Overhead Electrical Conductors - Creep Test Procedures for Stranded Conductor’. The object of the test is principally to calculate creep for any purpose and to compare creep of different conductors. The test finds out the inelastic nature of metal exposed to every day tension over years. The laboratory results are essentially used to produce long term room temperature tensile creep curve.  The tests are conducted at a constant (surface) temperature of 20º C ± 2º C maintained over the length of the conductor for a minimum period of 1000 Hours while the tensile load maintained at a constant load of 20 % of the rated tensile strength of the conductor under test. The creep curve and power-law equations are constructed for each load and extrapolated to 10 Years (87,600 Hours) which are used as a data and a key input parameter for the transmission line design in formulating the sag and loading conditions. It is preferable to test the same at different temperatures and at different tensile loads as also mutually agreed upon by the supplier and purchaser. (Fig no:05)

Cantilever Bending strength test

The bending strength test on various Insulators, bushings, CVTs, PTs etc. Has been carried out in our test bed as per National/International standards. The bending test has been accredited by NABL on the basis of its compliance to ISO/IEC: 17025:2017 in the field of mechanical testing.(Fig no:06)

Type Test Facilities for ACSR/AAAC Conductors

The Vibration laboratory has been established to undertake R&D and testing activities on bundle conductors, spacer dampers and other transmission line accessories. This is a unique facility in the country for testing bundle conductors. (Fig no:7 & 8)

The Facility Includes:

• Tensile Testing Machine
• Torsion Testing Machine
• Hydraulic loading Equipment
• DC Resistance measuring Equipment UTS test, stress strain test, Zinc coating test, wrapping test, preece test etc.