110 kV Bushing’s Test at –200 ºС

On 16 and 17 January 2017, for the first time in Russia, Izolyator plant held tests of a 110 kV HV bushing at –200 ºС.

R&D Director Konstantin Sipilkin says: “Today, the world’s leading research and development centers and power engineering companies are engaged in creation of new types of power equipment based on superconductivity effect. Cable lines, transformers, motors and current-limiting devices, — all that equipment can utilize superconductivity to operate. Evidently, for that revolutionary equipment, new high-voltage bushings, able to operate at low temperatures, will be required. Our specialists are presently working to create high voltage bushings of the type”.

The high voltage bushing of the type is a wall condenser-type insulator intended to make an HV current passage from the current-limiting device, cable or transformer operating on superconductivity effect. What is unique about the bushing is that its bottom part is designed to operate at –200 ºС.

The bushing, which underwent testing, was designed and made with RIN technology.

The solid RIN insulation (Resin Impregnated Nonwoven) has been developed by Izolyator’s design office in collaboration with partners with the aim to increase water-tight features of the internal insulation of the bushings in severe operation conditions.
The main insulation is a nonwoven polymer material that has no cellulose, and is, therefore, hydrophobic and possessing a resistibility to atmospheric humidity and heat resistance.
The material is void of water in the first place, which allows to eliminate thermal vacuum drying of wound core. This means a more reliable insulation and a shorter production cycle.
In all other details RIN insulation making process is identical to RIP technology.
RIN insulation can be used both with porcelain and polymer external insulation.
Izolyator has patented RIN trademark and production technology and received certificates of conformity of RIN bushings to Russian and international standards.

Unlike with a mass produced RIN bushing, special technical solutions were found for the bushing to be able to withstand temperature differential from -200 ºС in the bottom part to +10 ºС in the top of the bushing.

The test was organized and performed jointly with SuperOx company.

Andrey Vavilov founded SuperOx in 2006 with a goal to establish production of second generation high temperature superconducting tapes (2G HTS). The company’s intellectual property is based on more than the 30-year experience in deposition of complex oxide coatings and studying properties of HTS materials. SuperOx is headquartered in Russia and Japan.

The tests, with the bottom part of the bushing immersed in cryostat with liquid nitrogen, included:

• measurements of the bushing characteristics under 10, 76 and 126 kV before and after every type of the tests;
• application of a one-minute 230 kV voltage after every test, 6 totally;
• measurement of partial discharge level after every test;
• application of lightning impulse, 550 and 666 kV, 35 impulses totally.

After all tests completed, the bushing’s condition remained unchanged, which proves an immense reserve of cold endurance of the insulation. After the tests, the high-voltage bushing was sawed for evaluation of adhesion of the main insulation material to the insulation core plates.

The positive tests’ results allow Izolyator to commence designing similar bushings for higher voltage classes.

Participants of the 110 kV RIN bushing’s tests in cryostat at Izolyator plant