Yash Highvoltage Limited has completed seismic qualification testing of its 138 kV Oil-Impregnated Paper (OIP) condenser transformer bushing in accordance with IEEE 693 requirements and a response spectrum corresponding to a 0.5g seismic level. The test assessed the bushing’s structural and electrical performance under simulated earthquake conditions.
The qualification was conducted using a tri-axial shake table under conditions intended to replicate field installation. During the test, the bushing was mounted on a steel structure at an angle of 30 degrees from the vertical. The procedure covered instrumentation and calibration, identification of resonance nodes, seismic excitation, post-test checks and electrical testing before and after the earthquake simulation.
A 33-second time-history earthquake simulation was applied simultaneously along the X, Y and Z axes. The test covered frequencies ranging from 0.3 Hz to 50 Hz, subjecting the equipment to movement in multiple directions at the same time.
Following the test, Yash Highvoltage reported no cracking, oil leakage or visible damage to the bushing. The company also said there was no loosening, deformation or structural damage following the seismic sequence.
The maximum displacement recorded at the high-voltage terminal was 7.33 mm. The change in resonance frequency measured before and after the seismic test remained within the stated acceptance limit of 20%, according to the company.
The bushing subsequently underwent routine electrical testing and passed the tests after seismic exposure. Yash Highvoltage said these tests were conducted in accordance with IEEE C57.19.00/01 requirements at its 600 kV extra-high-voltage laboratory, which is certified to ISO/IEC 17025.
The company listed the successful qualification as a demonstration of the bushing’s structural integrity under the tested seismic conditions. The announcement forms part of Yash Highvoltage’s work on transformer bushing technologies designed for power-system applications where seismic performance is a consideration.
source:Yash Highvoltage® Carries Out Successful Seismic Test on Its IEEE Compliant 138 kV OIP Transformer Bushings
