| 摘要 |
A microwave oven includes a step-up transformer having primary and secondary windings, an inverter inducing a high frequency oscillating current at the primary winding of the transformer by an on-off operation of a switching element, a magnetron to which a DC voltage is applied by the transformer, a current transformer detecting an input current to the inverter, a control circuit for controlling "on" and "off" periods of the switching element so that a magnetron anode current is controlled, and a detecting winding arranged in the transformer so as to be magnetically connected to the primary winding. The detecting winding detects an induced voltage which indicates either a short-circuit or open-circuit in the secondary circuit of the transformer. The control circuit detects an abnormal condition of the secondary circuit of the transformer based on the induced voltage detected by the detecting winding. Upon detection of the abnormal condition, the control circuit operates to interrupt the operation of the switching element.
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