PURPOSE:To easily obtain three modes and make them usable by providing a pair of spring members energizing a different spring load in the facing direction to a movable block, and stopping the spring load energization of one side spring member with a stopper at the neutral position of the movable block. CONSTITUTION:Movable contact pieces 11 and 16 serve as spring members pressing a movable block 20 from a mutually facing direction via card parts 24 and 25 respectively, and the spring load f of one side movable contact piece 11 and the spring load F of other side movable contact piece 16 are different each other so as to be e.g. Ff. And the stopper 26 fixed to a base 2 is provided at the position where the spring load energization to the block 20 of the piece 11 is once stopped at the neutral position of the block 20. This makes it possible to select three modes, that is three conditions of an ON-OFF condition at the time of unelectrifying, an ON-OFF neutral condition at the time of electrifying, and an ON-OFF condition at the time of electrifying, only by changing the level of the impressed voltage to a coil 6.
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