| 摘要 |
A transformer protection device formed as an integral unit includes over-current protection including a two-pole current interruption device, a ground terminal, and overvoltage protection connected between at least one pole of the current interruption device and the ground terminal. Preferably, over-voltage protection is connected between both poles of the current interruption device and the ground terminal. Over-voltage protection means is then connected between the last-mentioned two terminals. The over-current protection may comprise a two-pole circuit breaker and the over-voltage protection may comprise two varistor disks. In a preferred embodiment, each of the varistor disks is held in electrical contact with one of the two poles by mechanical energy storage. Lightning surges or switching surges arising on the secondary winding are thereby shunted around the secondary winding instead of being reflected across to the primary winding at damaging stepped-up voltage levels.
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