Real-time software testing for microprocessor-based protective relays

This paper describes a new practical method, the domain-partition boundary method with software probes, and a test platform for testing real-time software embedded in protective relays. The test scheme automatically and efficiently exercises all functions of a relay in all of its operating domains, especially in the error-prone domains. While the test-case generation methodology belongs to the function-test class, it uses knowledge of the software modularity, and takes into consideration system specification and behavior, critical parameter boundary values and software flow in generating the test specification. TSL¹ is used for managing the test-case generation process, and avoids redundancy. A microcomputer test platform was designed and assembled. It is a simulator which produces voltage or current levels that correspond to events in the system. A control program manages the overall process, including test case generation, wave-form production, process timing, event identification, data collection and result comparison. An implementation of the test scheme is described. Actual testing was conducted on a motor control and overload protection device for verifying its functions, but the test scheme is applicable to other microprocessor-based devices