| 摘要 |
Since the position of the phase conductor and neutral conductor on plug sockets of the AC voltage mains is in general not known, a circuit is required for some applications which has a constant, unambiguously defined polarity on its output connections despite a changing polarity on its input connections. A polarity-reversing circuit which can be used in this case must ensure with a high degree of safety that contaminating effects such as arcs or switch bouncing cannot lead to a short-circuit between the neutral conductor and the phase conductor in any circumstances. For this purpose, two switches (K1, K2 and/or K3, K4), which are controlled by separate relay windings (R1, R2), are allocated to each output connection with a defined polarity (D and/or E). The switches (K1, K2 and/or K3, K4) change over as a function of a polarity-control circuit, which is oriented on the basis of the polarity of the input connections, so that the defined output connection is in each case connected to the input connection which corresponds to its predetermined polarity. In this case, the switch which changes over from a live contact to a contact which is free of current is in each case switched in advance. <IMAGE>
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