This handbook covers the code of practice in protection circuitry including standard lead and device numbers, mode of connections at terminal strips, colour codes in multicore cables, dos and donts in execution. able sources such as wind and solar. These clean energy sources, connected through inverters and flexible transmission systems, are transforming traditional grids based on synchronous generators into more flexibl cant challenges to system stability. Nowhere is that clearer than in the challenge to. IEEE/IAS/I&CPSD Protection & Coordination WG Chair Jacobs Canada, Calgary, AB rasheek. Also principles of various protective relays and schemes including special protection. The International Electrotechnical Commission (IEC) is currently working on a new series of standards that covers the functional requirements of measuring relays and related equipment used to protect electrical transmission and distribution systems.