"Power Shield" is a solid-state trip device used to protect the power system against damage caused by overloads and faults. It is supplied as an integral part of the circuit breaker, types K-600S through K-4000S, K-DON600S, K-Don 800S, and K-Don 1600S. The long-time, short-time, and instantaneous trip elements perform essentially the same protective function as provided by the electro-mechanical trip devices, but with greater accuracy and selectivity. The ground-trip function can be included in any model for those applications in which it is desired to protect the system against faults to ground. These are often arcing faults which result in currents whose magnitude is less than normal load current, but require detection due to the damage which may result from the arc. "Power Shield" is completely tested prior to shipment. Since there are no mechanical devices which may have lost adjustment during shipment, no readjustments need be made prior to placing in service. Nor is maintenance required in the usual sense of cleaning, adjusting, or lubricating. The frequency of testing will vary from user to user depending on many factors. A typical interval of 1 to 2 years is suggested.