Milestones:Gapless Metal Oxide Surge Arrester (MOSA) for electric power systems,1975


Gapless Metal Oxide Surge Arrester (MOSA) for electric power systems,1975


Gapless Metal Oxide Surge Arrester (MOSA) for electric power systems,1975

Meidensha Corporation developed MOSA and its mass production system by innovating on Panasonic Corporation’s ZnO varistor basic patent. MOSA dramatically raised performance levels against multiple lightning strikes and contamination and led to the UHV protective device development. This technology contributed to improving the safety and reliability of electric power systems and to establishing the international standards.

Street address(es) and GPS coordinates of the Milestone Plaque Sites

{{{gps}}}, Meiden R&D Center Meidensha Corporation  2-8-1, Osaki, Shinagawa-ku               Tokyo, 141-8565, Japan 

Latitude: 35.637915 Longitude: 139.715213

Details of the physical location of the plaque

We intend to install the milestone plaque at the secured zone in the entrance of Meiden R&D Center.

How the intended plaque site is protected/secured

The people are able to see the plaque in the secured zone by getting inside the entrance hall of Meiden R&D Center.

Historical significance of the work

Overvoltages in electrical supply networks result from the effects of lightning strokes and switching actions and cannot be avoided. They endanger the electrical equipment, because, due to the economical reasons, the voltage withstanding capability of the insulation cannot be designed for all possible cases. Therefore, an economical and reliable service calls for extensive protection of the electrical equipment against unacceptable overvoltages. This applies to all power network systems.

The overvoltages from lightning strokes and switching action are most dangerous threat for power electric systems. The so called “conventional surge arresters” were mostly used in power electric systems until mid 1980s in the world. They consist of a series connection of SiC resistor elements (non-linear resistors) and spark gaps and are placed in porcelain housing and are often called “conventional gapped type arresters”.

Conventional gapped type arresters have a couple of disadvantages: They reduce overvoltages only when the breakdown voltage of the spark gaps is achieved. The breakdown voltage of the spark gaps depends on the steepness of the incoming voltage which results in a bad protection especially for steep overvoltage. If the outside insulation of the arrester is polluted, the potential distribution can shift along the active part, and this can cause unwanted sparkover in the spark gaps, which in the end may destroy the arrester.

Design of insulation in the power transmission system depends largely on the protective characteristics of surge arresters. As the power grids were expanding with higher transmission voltage in 1970s, the conventional gapped type arresters used before the introduction of the work could not satisfy the new requirements.  The conventional gapped type arrester was sometimes failed by natural phenomena for example multi-lightning and arrester housing pollution (contamination).

Electric power utility companies demanded the development of high performance surge arresters to be used for the next-generation UHV power transmission systems and also compact high-performance and high-reliability surge arresters to be used in the application for GIS (tank type arrester for gas insulated switchgear).

Panasonic Corporation (Panasonic) had discovered ZnO varistor as a surge absorber for electronic devices below dozens of volts and defined its basic principle. Meidensha Corporation (MEIDEN) developed gapless surge arrester for power electric systems based on Panasonic’s patent. MOSA was the first gapless surge arrester that could meet the tough electric power systems application needs of world-wide power utilities. Consequently, conventional gapped type surge arresters were disappeared except some special applications.

MOSA has contributed to improving the reliability against multi-lightning and housing pollution-derived problems. Furthermore it ignited the births of economical design for power network systems and power electric equipment. MOSA became the de facto standard and later turned to JEC [1], ANSI [2], IEC [3] standards. It realized the electric power systems which has the very minimum power failure in the world.

Features that set this work apart from similar achievements

Conventional surge arresters for electric power systems were composed of combination of non-linear resistor element using silicon carbide ( SiC ) crystals and series gaps. As a result, they had the following disadvantages; a) They couldn’t have high reliability against the housing pollution. This causes failure of arrester derived from two different components (gap part and SiC element) in same housing and couldn’t maintain stability for multiple lightning.

b) They couldn’t satisfy the social ( user’s ) requirements for high-performance, high reliability and compactness of arresters both for GIS ( Gas Insulated Switchgear / Substation ), and for Ultra High Voltage (UHV) transmission systems.

Overcoming obstacles cited above, MEIDEN developed gapless surge arrester to solve the above issues of conventional model: a) and b). MEIDEN commercialized MOSA in 1975 and the first supply was to 66kV Hayato Substation in Kyushu Area, Japan and completed the MOSA product series for 3kV to 500 kV electric power systems during 1977-1978. MOSA became the preferred choice and de facto major arresters in the world in a few years.

Significant references

[1] JEC 217-1984 (Japanese Electrotechnical Committee Standard in English)  [2] IEEE/ANSI C62.22-1987 [3] IEC 60099-4-1991 [4] T. Nishikori, T. Masuyama, M. Matsuoka, S. Hieda, M. Kobayashi and M. Mizuno: “Zinc Oxide-based Gapless Surge Arrester for Electric Power Systems”, Paper for National Convention The Institute of Electrical Engineers of Japan (IEEJ), No. 777, 1973 [5] M. Kobayashi, M. Mizuno, M. Matsuoka and M. Tanaka: “Gapless Surge Arrester for Electric Power Systems”, Paper for Research Conference , IEEJ, PD-74-12(1974) [6] M. Kobayashi, M. Mizuno, T. Aizawa, M. Hayashi and K.Mitani:  “Development of Zinc-Oxide Non-Linear Resistors and Their Applications to Gapless Surge Arresters”, IEEE PAS, Summer Meeting, F77, 682-8 (1977), IEEE, Transactions, vol. Pas-97, No.4 (1978) [7] M. Hayashi and M. Kobayashi : “Developing the First Gapless Metal Oxide(ZnO) Surge Arrester(MOSA) in the World “, IEEJ, Trans. PE, Vol. 128 No.3 (2008) [8] K. Mitani: “Journal: Birth of Gapless Surge Arrester for Electric Power Systems”, Serial Articles of power industry newspaper “Denki Shimbun”, from Nov. 30, 1978 to Jan. 21, 1979 (6) [9] Misao Kobayashi and Masao Hayashi: ”The background and history of developing Gapless Metal Oxide Surge Arrester (MOSA)”, Papers of Research Conference, History of Electrical Engineering (HEE), IEEJ, HEE8-19 and HEE10-002  [10] United States Patent 4,031,498 NON-LINEAR VOLTAGE-DEPENDENT RESISTOR

Supporting materials

[11] Picture of MOSA for 66KV system used in Japanese electric company in 1975 [12] Picture of MOSA for 500kV GIS used in Japanese electric company in 1979 [13] Picture of MOSA for 500kV system used in Canadian electric company in 1979