Name / Eugene Knabe / Session / ALPHA1
Company / Cooper Power Systems / Block / 1
Address / 1045 Hickory Street / Question n° / QUESTION 1-5
Pewaukee, WI 53072 USA / Language used on the floor / ENGLISH
Phone / (262) 691-8266 / Accompanying visuals on file ? / NO
e-mail /
USE OF PROTECTION SWITCH & PARTIAL-RANGE CL FUSES
The MagneX Interrupter, as described in the paper “Three-Phase MagneX: An Alternative to Conventional Distribution Transformer Protection,” is generally considered a transformer component that is part of an integrated protection scheme for padmounted transformers. The combination of the MagneX in series with a partial-range current limiting fuse provides similar full-range overcurrent protection that is available from full-range HRC fuses, but with the ability to reset the low-current clearing device upon operation on overload conditions.
The paper describes the option of employing a protective device that is thermally responsive to the capability of the transformer to sustain overloads. Provided that the transformer can dissipate the heat generated from an overload condition, no loss of life is experienced. The ability of a protective device to respond to potentially damaging heat rise within the transformer provides functionality that was not previously available.
While the three-phase version of the MagneX is new, the single-phase version of the product has been in use for several years. Utilities in the Far East, such as Taiwan Power and Korean Electric Co. have used the combination transformer protection scheme extensively for several years. In addition, utilities in Central America have recently adopted the single-phase version of the MagneX, as an alternative to secondary breakers. Union Fenosa in Spain has been using single-phase MagneX in padmounted transformers for several years and has recently introduced use of the three-phase version into their specifications.
Advantages that these utilities see in the integrated protection scheme include, overload sensitivity, self-contained protection for high contamination areas, resetability without the need for stocking and replacement of fusible elements, fixed protection characteristics versus potentially unreliable fusing characteristics and the ability to switch the transformer on the primary-side.