Executive Summary

Power blackouts are a frequent occurrence in industrial facilities. The reason could be a fault in the utility side or a fault on the load ends of the feeders. How will we get to know whether a circuit breaker is capable of interrupting these electrical faults in the system? If these high fault currents exceed the interrupting capability of the protective device, it results in an increase in the likelihood of an explosion which could potentially damage the device itself.

The answer lies with a coordination study, which could help in preventing a certain equipment failure from taking down the entire facility resulting in a blackout.

Objective

A coordination study is used to analyze the short circuit currents and achieve an optimal balance between equipment protection and fault isolation that is consistent with the operating requirements of the electrical network.

Study Methodology

A protective device coordination study evaluates the effects of equipment failures and fault currents within a power system and analyzes the impacts on the system operation. Data collection procedures are performed as per NEC requirements, after which a comprehensive model of the system is developed on power systems software. A short circuit study is first performed to calculate the fault currents at each electrical point in the system.
The protective devices are then selected and adjusted to minimize the impact of equipment failures within a system. The time-current characteristic curves of the protective devices are analyzed and comparisons are made to identify areas of mis-coordination. Adjustments are done for each case, thus ensuring the best achievable coordination.

Study Outcomes & Recommendations

Coordination studies are performed as per the latest IEEE, NEC, ANSI & NFPA standards. Study outcomes and recommendations are expected to improve your facility in the following areas:

• Overall reliability of the system is expected to increase
• Significant improvements in the fault isolation at each point
• Reduced power blackouts within the facility
• Damage reduction to the existing protective devices
• Minimization of nuisance tripping caused by motor starting and transformer inrush currents
• Selective coordination for life safety systems as per NEC standards

Study Deliverables

The proven expertise of our team of certified professional engineers will aid in the evaluation of your system and deliver state-of-the-art coordination solutions for your power system’s protection. We work closely with our clients in collecting the data, modeling the system, simulating faults and abnormalities, plotting the characteristic curves & offering solutions in compliance with the latest industrial standards.

AllumiaX, LLC provides independent and third-party engineering support by presenting comprehensive deliverable reports backed by industry standards and best practices, analysis work based on industry-leading software (ETAP), and proven results based on accurate modelling and calculations. The reports are expected to include the following deliverables:

• A comprehensive model of the facility in modern power systems software
• Evaluation of the system under short circuit conditions for normal and emergency scenarios
• Accurate models of the characteristic curves on log-log plots
• Comparative analysis between the upstream and downstream protective devices
• Protective device settings for achieving selective coordination
• Relay settings for optimum protection of each protective device
• Recommendations for the prevention of power blackouts
• Tabulated results of the study in compliance with NEC, IEEE ,ANSI & NFPA standards

References

• NFPA 70, “National Electric Code” ,2017
• NFPA70E, “Standard for Electrical Safety in the Workplace”, 2017
• IEEE Recommended Practice for Protection and Coordination of Industrial and Commercial Power Systems, pp. 242-2001, 2001.
• IEEE Recommended Practice for Industrial and Commercial Power Systems Analysis, pp. 399, 1997