An arc flash hazard happens when current flowing through a system takes a detour and flows through the air in between the conductors. The impact of arc flashes varies with incident energy levels, which defines the heat energy received by a surface at a certain distance from the arc. The data from the arc flash study can be used to select the appropriate PPE and implement safe working distances.
Protective relays, if worked in coordination help reduce the incident energy levels at various parts of the system. Here’s how it works:
Protective relays and breakers trip and isolate the fault section in case of an incident. Proper relay coordination ensures that the nearest relay to the fault trips first, clearing the fault as quickly as possible. Reduced clearing times directly reduce the arc duration, lowering the incident energy released.
Arc flash safety studies recommend adjusting relay settings (e.g., time-current curves, instantaneous trip levels) to reduce fault-clearing times. Relay settings can be configured to trip faster in certain zones with high incident energy, without compromising system stability.
The relays are coordinated in such a way that only the affected part is isolated, which prevents unnecessary tripping of upstream relays and breakers.
Arc flash relays with special sensors help detect the arc flashes as and when they happen and through installation of proper protection devices, can reverse faults, thereby reducing arc flash risks.
If relays are properly coordinated, multiple faults can be detected and reversed on time. This significantly reduces the risks of arc flashes in a facility.
TCCs reveal whether the relays operate in sequence without overlapping trip times.
Arc flash studies give an overview of how these TCCs adjusted to find the balance between faster fault clearance and maintaining system stability.
Instant tripping of relays is essential for arc flash mitigation. Protective relay settings can be adjusted with the help of data from arc flash analysis and relays coordinated for arc flash protection.
Fuses or reactors can be integrated based on the data obtained from relay coordination study and arc flash analysis to limit the fault currents in the system.
Compliance Standards in Relay Coordination and Arc Flash Study in Australia
Relay, circuit breakers, and fuses are all protective devices that are critical for any power system operation. Hence, proper coordination of relays is one of the determining factors in reducing arc flash incidents in a facility.
The main advantages of relay coordination for arc flash safety are:
To conclude, it is a verified fact that relay coordination offers arc flash safety for power systems in Australia. By optimizing fault-clearing times and ensuring that protective devices trip selectively and quickly, incident energy levels can be significantly reduced. Protection od personnel, compliance with standards, and general workplace safety are ensured. Investing in relay coordination study can reap countless benefits, including arc flash safety for Australian industries.
