| 摘要 |
Disclosed is a low-frequency electromagnetic induction heater which comprises a heating element and at least six induction coils each having a circular configuration. The coils are connected in a three-phase double delta connection, are arranged in a circular and symmetrical configuration, are enclosed in a resinous mold and form three sets of coils such that each set of coils receives electrical power in a different phase from a three-phase low-frequency electrical power source, such as a commercial three-phase alternating current power source. The coils are interconnected such that the current flows from one coil to another coil placed opposite to the said one coil in the circular configuration. In a preferred embodiment, the heater consists of six coils. This invention provides for heating of the heating element with continuous attraction to the induction coils, a substantial increase of electromagnetic flux density, prevention of noise due to electromagnetic vibration of the heating element, and high thermal efficiency.
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