Current Limiting Protector for Industrial Applications

The development, the testing, and the application of the current limiting protector (CLP) and a compatible current level sensing and trigger circuit are described. The CLP consists of a current carrying main conductor and a parallel fusible element. In response to a short circuit, gaps are formed in the main current path by pyrotechnic cutting. The gap arc voltages commutate the current to the parallel fusible element, which then interrupts the current in a current limiting mode. High-power tests in 4-15-kV circuits limited prospective short circuits of 40-kA (rms) to less than 15 kA. The CLP offers single shot current limiting protection with low let-through I2t.