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ОАО «YuAIZ»

Yuzhnouralsky Insulators and Fittings Plant (OAO YuAIZ) was founded in 1957 and now is an unique enterprise in the energy sector, uniting on the same area a few production facilities: glass insulator production, ceramic insulator production, forging and casting workshops. OAO YuAIZ is part of the company Global Insulator Group (GIG).

Insulators for DC lines.

High-voltage direct current lines (HVDC) are used for transmission of large

electrical power. At long distance power transmission HVDC systems provide less

costs and electric losses. Even for short distance power transmission, where the costs

of converting equipment for HVDC systems are comparable to costs of AC systems, DC

lines have more advantages.

High voltages are used for saving energy loss caused by the conductors’

resistance.

Below shows the external value of HV projects with AC and DC currents.

The calculations were provided by the company АВВ for projects with total length above 2000

km and with transmission capacity of 6000 MW.

As Figure 1 shows, the construction cost of DC line (800kV) is 2.5 times lower that of the AC

line (765 kV). Savings of the electric losses also gives significant economy effect. On the other hand,

DC line means considerable expenses on construction of the substations. Nevertheless, lowering

the expenses on DC lines means reduced amounts of insulators supplies as compared to AC

projects.

Figure 1.

1. SEVES (SEDEVER) is Biggest manufacturer and suppliers for toughened glass insulators 2. NANJING ELECTRICITY (GROUP) Co., Ltd. Glass DC insulators rated for 160 kN, 210 kN and 300kN (with modification U300BP). Insulators LXZY -160 (210, 300). 3. ShandongRuitaiGlassInsulatorCo., Ltd Glass DC insulators for railway systems. 4. NGKInsulators, Ltd During the last 20 years has supplied more than 70% of porcelain suspension insulators for the following HVDC projects: ± 350 kV Leyte - Luzon, Philippines ± 450 kV James Bay, Canada ± 500 kV Rehand - Delhi, India ± 500 kV Gezhouba - Shanghai, China ± 500 kV Chandrapur - Padghe, India ± 500 kV Anan - Kihoku, Japan 5. Bharat Heavy Electricals Limited (BHEL) Porcelain disk insulators, developed and Bharat Heavy Electricals Limited (BHEL). Tests were carried out in laboratory STRI (www.stri.se). Insulators were supplied for 800 kN HVDC Biswanath-Agra project. 6. DALIAN INSULATOR CO. LTD. P.R. CHINA Porcelain DC suspension insulators rated from 70 to 530 kN, from 35 to 800 kV AC/DC.

Manufacturers of HVDC insulators

7. Yuzhnouralsky Insulators and fittings plant (OAO “YuAIZ”).

Produces glass insulators, porcelain insulators and line fittings for all voltage ranges

for AC transmission lines.

In 2015, based on the requirements analysis and performance experience the

engineers of the plant have developed the technology for production of DC glass shells

for DC insulators assembly.

The developed types are rated for 120kN, 160kN, 210kN and 300kN load and have

increased creepage distance. All mechanical and electrical parameters are given in the

design documents for each type, and proven by the test reports. Test centre of the plant is

accredited as per IEC 17025 and is capable of performing routine, type and acceptance

tests.

Insulator for line DC production of YuAIZ.

The requirements for DC insulators production and testing are stated by the international standard IEC 1325-1995-03.

Insulators for DC lines require special design and insulating materials because of the certain performance demands.

Due to corrosion caused by the unidirectional current, zinc sleeve on a pin and zinc collar on a cap is a must.

General dimensions, mechanical and electrical characteristics are verified by the tests in accordance IEC60383-1.

Special requirements and tests

1. Withstand DC voltage in SF6 gas. Insulators are tested in a chamber with gas pressure with voltage 1.5 times higher than the specified DC withstand voltage (dry). 2. Electrical body resistance is measured between cap and pin at 120°C.

The diagram shows the resistance-

temperature relationship of the

glass shell as per IEC61325.

3. Ion migration test is defined as the transmission of the certain charge for 50 years.

Formula of the test dates determination:

Test results were obtained during the tests on DC insulators in YuAIZ Test Centre

At t=90°C, resistance R=17,5∙1010 Ohm

At t=120°C, resistance R=1,47∙1010 Ohm

At t=150°C, resistance R=2,65∙109 Ohm

test

test

VRQD

×××

=243600

)(50 θ

The picture shows the ion migration test equipment.

4. Thermal runaway test is defined as subjecting the insulator to 8 hours of 110kV voltage at 80°C. 5. Verification of the zinc sleeve and zinc collar. Purity of the zinc should be not less than 99.8%. The adhesion surface area for cap and pin should be no lower than 80%. Sampling and acceptance criteria are defined by the international IEC61325.

The picture shows the steep front wave test on HVDC insulator

Thank you for your attention

Best regards,

Vladimir Golovin October 2015.

References: CIGRE Calgary 2007. J.M.GEORGE “Evaluation of electrical and mechanical performance for glass insulators used at DC lines”. CIGRE TORONTO 2009. J.M. GEORGE «Selection criteria for insulators used for DC transmission lines».