Before a substation can become operational, it is important to conduct thorough checks to ensure it is safe for the electrical conditions that are likely to emerge and the physical environment in which it is going to operate. The relevant authorities, such as the Essential Energy (EE) needs to ensure that critical tests are instituted before commissioning the substation. Substation testing and monitoring involve the following:
Inspection of all electrical equipment
Authorised Representatives (AR), or any contractor approve by the EE, are responsible for conducting visual checks on all electrical equipment at the substation. They check for any internal or external damages that may have occurred during transit or erection, and if any are present, they rectify them accordingly. Some of the tests necessary at this stage include AC and DC supply checks, Scheme Checks, Internal Panel Wiring and Compliance Visual Check.
Electrical engineers should carry out standard earthing tests at the beginning of the contract. It is part of the Earthing design brief, and it establishes the earth resistivity of the site for the substation. Once the earthing tests are complete, a copy of the results should be forwarded to the PCE for approval. The erection staff will repeat the earthing tests in the presence of a commissioning team and client during the acceptance stage.
Substation Testing also involves bus wiring tests. These tests include checking the inter-panel bus wiring to determine if they are in line with the appropriate termination diagrams. To accomplish such tests, engineers use the 500V Megger o check the insulations from bus wires to earth and other connection points. It is essential to check individual fuses, miniature circuit breakers, links and all incoming and outgoing circuit panels.
Testing batteries and chargers
Batteries and chargers are tested to see if they meet their manufacturers’ guidelines. These checks also determine that the batteries and chargers are functioning properly and are within the recommended limits of tolerance. This test also ensures that their performance is satisfactory during the commissioning of the substation. The charging and discharge times are also established and witnessed by the client at the end of the commissioning program.
Testing Multi-core cables
Testing and checking of the multi-core cables are conducted according to the appropriate termination diagrams. A 1000V Megger comes in handy in determining the resistance of the insulation of these wires. This is done at the pre-commissioning stage to find out if there are any problems. The process is also repeated during the commissioning of the substation.
132kV GIS site Testing
Engineers carry out several tests and ensure they are in agreement with the Works Site Test Report. Some of the checks here include:
- Compressed air system sequence checks
- Air and gas leakage tests
- Bus-bar and connections
- Mechanical and local electrical operational checks
- Circuit breaker and contact resistance checks.
132/ 11.5kV 30MV Transformer Site Testing
Substation testing and monitoring would not be complete without testing and inspecting the transformers. The process involves oil testing, as well an all cables within the transformer. All the checks should be conducted according to the factory check sheets and installation of transformers. Engineers continue to monitor the transformers even when fully operational to keep an eye on the oil level and general working of the machines.
Checking the Shunt reactor
Shunt reactors are an integral part of substation systems. Their wellbeing determines how safe and efficient the power distribution will be. Therefore, regular tests and checks are crucial in establishing their efficiency. Some of the tests here include winding insulation level, oil tests, and visual checks. The oil and winding temperature gauge calibration fan control sequence tests is also important.
Substation testing and monitoring involve many activities that ensure safety and efficiency of the substations. It is a series of tests and checks on electrical equipment, earthing, bus wiring, and checking of the multi-core cables. Other necessary checks include batteries and chargers, the shunt reactor and the 132kV GIS site tests. All the tests are instrumental in ensuring the success of the substations. It is a crucial part of the commissioning of the substations.