Discrimination Power Study

Discrimination Power Study, also known as Selectivity Analysis, is a process used to evaluate the protective devices (such as circuit breakers and fuses) in an electrical system to ensure that they operate selectively during fault conditions. The purpose of discrimination is to isolate the faulty section of the system while minimizing the impact on the rest of the system, thus maintaining continuity of power supply and enhancing safety.

Here are the key aspects and objectives of a Discrimination Power Study:

1. Fault Current Analysis: A Discrimination Power Study begins with analyzing the available fault currents at different points in the electrical system. This involves calculating the prospective fault currents that can occur in various fault scenarios, such as short circuits or overloads.
2. Coordination of Protective Devices: The study evaluates the coordination or selectivity between protective devices, such as circuit breakers and fuses, at different levels in the system. Coordination ensures that the device closest to the fault operates to clear the fault while maintaining the operation of other upstream devices. This prevents unnecessary tripping or disconnection of non-faulty parts of the system, reducing downtime and improving system reliability.
3. Time-Current Curves Analysis: Time-Current Curves (TCCs) represent the operating characteristics of protective devices, illustrating their trip times in response to different fault currents. The Discrimination Power Study compares the TCCs of various devices to determine if they are properly coordinated and if any adjustments or modifications are necessary to achieve the desired selectivity.
4. Selectivity Settings and Adjustments: Based on the TCC analysis and coordination requirements, the study determines appropriate settings or adjustments for the protective devices to achieve selectivity. This involves adjusting time delays, current settings, or other parameters to ensure that the downstream device closest to the fault operates before the upstream devices.
5. Protection Scheme Recommendations: The Discrimination Power Study provides recommendations for enhancing the selectivity and coordination of protective devices. This may involve suggesting additional protective devices, modifying settings, or implementing backup protection schemes to ensure fault isolation and minimize system disruptions.

The benefits of conducting a Discrimination Power Study include improved system reliability, reduced downtime, enhanced safety, and compliance with regulatory requirements. By identifying and rectifying any coordination issues or inadequate selectivity, the study helps optimize the performance and protection of the electrical system.

It is important to note that Discrimination Power Studies should be performed by qualified electrical engineers or power system consultants with expertise in protective device coordination and system analysis. The study may involve utilizing specialized software tools to simulate fault scenarios, analyze TCCs, and evaluate coordination.

Overall, Discrimination Power Studies play a crucial role in ensuring the effective operation and protection of electrical systems, minimizing the impact of faults, and maintaining continuity of power supply.