Suspension overvoltage limiting method for polarity selection switch

The invention discloses a suspension overvoltage limiting method for a polarity selection switch, and the method comprises the following steps: 1), building a transformer winding load voltage expression containing the polarity selection switch according to the working principle of the polarity selection switch; 2) according to the transformer winding load voltage, establishing a recovery voltage and breaking current expression of each contact of the polarity switch; and 3) according to the recovery voltage and the breaking current of each contact of the polarity switch, judging whether the tapping winding needs to be connected with a potential resistor for limiting the suspension overvoltage, and determining the number and the connection mode of the connected potential resistors. The invention provides a technical scheme for effectively inhibiting the suspension overvoltage of the polarity switch, and can effectively avoid the condition that the insulation of the transformer is endangered by the short circuit