Design & build a protection relay test set

Abstract

In electrical installations on the main switchboards, protection relays like Overcurrent Relays, Earth Fault Relays, etc. are installed after a Circuit Breaker (CB), designed to trip the respective CB when a fault is detected to protect the end-user / equipment. Shutdown maintenances are carried out periodically on most electrical installation to test the functionality of components within the electrical installations. As part of the shutdown maintenance work, Secondary Injection (SI) tests are carried out on the protection relays to ensure that the relays are still functioning. Protection relays to be tested can be as much as a hundred relays, all to be tested within a tight time frame. Protection relays found/tested faulty will be highlighted and seek approval from client for immediate replacement. Getting the approval from client will often take time, hence time taken to finish testing all relays is essential. This is to ensure that faulty relays can be replaced within scheduled shutdown timings to avoid delays in restoration of power supply to the estate. The test set that are usually used for the protection relay testing is costly and bulky as it can also carry out other different tests such as Primary Injection test, SI testing of three phase relays which are used in the higher voltage installation. Weighing at more than 20 kilograms (kg), a lot of time and effort is spent moving the bulky and heavy test set around. Regardless of the estate intake capacity, most of them will have a Low Tension (LT) switchboard, up to 400 Volts(V) three-phase line to line, before distribution of power to consumers. Hence, it is very common and mostly only single-phase protection relays to be tested. The other various tests that the bulky test set offers are not required. Hence, the aim of this project is to build a smaller and cheaper SI test set.