APPARATUS AND METHOD FOR TRANSIENT BLOCKING EMPLOYING RELAYS

摘要

An apparatus and a method for uni-directional and bi-directional transient blocking. The uni-directional apparatus has a depletion mode n-channel device at its input and a normally closed relay, e.g., a micro-electro-mechanical (MEM) relay, interconnected with the depletion mode n-channel device and the input in such a way that at a predetermined current value the transient causes the normally closed relay to switch into an open state and produces a bias voltage V<SUB>n</SUB> on the depletion mode n-channel device that is sufficiently high to switch it "off" and thus block the transient. An analogous arrangement at the output taking advantage of the same or a second relay renders the apparatus bi-directional. The structure of the apparatus and the method of operation ensure a reliable and repeatable trip current I<SUB>trip</SUB> and render the apparatus very robust and feasible for low-cost manufacture.