Shunt Reactors
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Shunt reactors In the early 1970's, Trench embar-ked on a development program to increase the application size of shunt connected, air core, dry type reactors. In the mid 1970's Trench manufactured and successfully tested an 18 MVA single phase, tertiary connected shunt reactor. The basis of the design for this reactor forms much of the present day design guidelines for Trench shunt reactors, rated as high as I00 MVA per phase or suitable for direct wye connection to 115 kV systems. The following, outlines the important technical areas which Trench addresses, in order to provide customers with highly reliable, large MVA shunt reactors. Thermal Criteria for Insulation Shunt reactors are subjected to continuous full load current when connected, and as such operate at maximum design temperature rise. Although shunt reactors can be designed with various insulation temperature classes, a 130 deg. C class, polyester insulation is most prevalent. It must be ensured that no part of the winding of the shunt reactor exceeds 130 deg. C for any significant time. Both, Trench parallel wire and Trench cable designed reactors address this important issue. For small wire, parallel layer winding designs, Trench developed a highly accurate computer design program which precisely calculates the number of conductor turns required to carefully control and ensure that excessive current is not carried by any part of the win-ding. Excessive current can lead to high temperatures which would shorten insulation life expectancy. By maintaining tight construction tolerances, current distribution, verified by temperature rise tests, is kept virtually equal in all parallel winding layers. Trench cable wound shunt reactors are not subjected to current imbalances, as all parallel conductors are twisted or transposed into a custom made cable package. The geometric profile of the cable is controlled to ensure that an exact number of turns are produced in the winding height design. Voltage Withstand Levels Shunt reactors are connected in either wye or delta configuration. This means that full line-to-line or line-to-ground voltage appears continuously across the reactor. In addition, reactors must be rated for full impulse (BIL) withstand. Trench shunt reactors are designed with conservative voltage stress parameters. Steady state voltage stress across the coil surface is well below the voltage level which could lead to partial discharges and subsequent deterioration of the external insulation. Steady state turn to turn voltage stress is also designed to be well below the level which could lead to partial discharge and internal insulation damage. e THE H

Losses Vibration and Noise As far back as the mid 1970's, shunt reactor losses have been of concern to electric utilities. In order to minimize losses, shunt reactor specifications normally include a loss evaluation formula which is intended to optimize, or balance, the reactor total losses versus reactor cost. Now, into the century, cost of energy has risen dramatically and as such losses are of much more interest. The largest percentage of reactor total losses originates from the conductor winding (I2R). To decrease losses from this area, Trench can increase the cross-sectional winding,...

Trench Facilities Trench® Austria GmbH Paschinger Strasse 49 Postfach 13 A-4060 Linz-Leonding Austria Phone: 43-732-6793-0 Fax: 43-732-671341 Trench® Brasil Ltda Via Expressa de Contagem, 2685 Contagem, Minas Gerais CEP 32370-485 Brazil Phone: 55-31-3391-5959 Fax: 55-31-3391-1828 Trench® China MWB (Shanghai) Co., Ltd. No. 3658, Jiancheng Road Minhang, Shanghai Peoples Republic of China 200245 Phone: 86-21-54720088 Fax: 86-21-54723118 Trench® High Voltage Products Ltd., Shenyang No. 2 Zhengliang Er. Road Jing Shen Xi San Street Dao Yi Economic Development Zone Shenyang 110136 P.R. China...