15 practical safety measures to prevent electrical hazards both for people and assets

In the face of the internal arc fault hazard present in low and medium voltage switchgear, the reliable risk prevention for the personnel and the electric installation itself can be achieved by following this proven formula.

ABB’s formula for safety



Condition


Knowing and improving the condition of the equipment is a key factor in reducing the likelihood of failure, damage, and injury.

1. Risk Assessment study
Asset risk assessments to establish the risk profile of equipment based on its condition and importance in the system, and prioritize actions to mitigate the risk before the hazard occurs
2. Monitoring programs
Risk monitoring and mitigation programs to maximize improved reliability and reduced operator exposure
3. Upgrades and retrofit
Equipment upgrades and retrofit which decrease operator exposure because of reduced maintenance, faster cycle times, and lower clearing times
4. Diagnostic testing
Diagnostic testing to address concerns of bad connections, pollution, mechanical faults and minimize failures due to defective devices

Distance


Maintaining a safe distance between personnel and equipment during critical operations provides the most effective means of avoiding injury by keeping people out of harm’s way



5. Remote racking
Remote racking provides a safer operating environment for personnel through the proven method of adding distance between the operator and arc flash incident energy at the switchgear site, bringing operation of power circuit breakers to a new level of safety.
ABB vacuum circuit breakers can be provided with a fully integrated motor operated racking system for their use in new replacement switchgear or as part of the hard-bus and cradle-in-cradle retrofill solutions
6. Voltage indicators
The installation of voltage indicators on accessible power circuits can increase the operators safety and avoid accidental electrical contact injuries. VisiVolt is an ABB passive voltage indicator perfectly suiting the equipment upgrade. It is adapted for permanent installation on busbar and naked or insulated metal conductors, indicates the presence of voltage by displaying a large and well visible lightning arrow sign on its display. The relevant silicone elastomeric enclosure ensures performance also in outdoor conditions while its fluorescent orange color provides good visibility among the other elements of the system.
7. Infrared thermo-graphic inspection
Infrared (IR) thermal measurements are performed through dedicated arc-proof ports with power compartment doors closed. The periodic thermo-graphic inspection of the critical areas (e.g. power cables connections) is an efficient method for preventing associated faults. Ports can be added to existing switchgear by ABB expert engineers keeping the original equipment design characteristics.
8. Partial discharge measurements
Periodic measurement of the partial discharge (PD) level is a proven method for detecting insulation degradation before real insulation failure develops. The assessment results are documented as trend curves for each switchgear compartment, where the curves with high increase of partial discharge activity level indicate compartments with high risk of insulation failure. Site work is performed with closed doors.

Time


Reduction of time for clearing fault conditions has a dramatic impact on the energy released and consequent damage and injury.



9. MV equipment faults:
relay upgrades
relay upgrades with Relion® microprocessor equipment which operate faster than electromechanical relays and support faster clearing times.
10. Short-circuit current:
Is-Limiter device
Is-limiter device as a fast operating interrupting device that limits the short circuit current to a level that breakers and buses can withstand, protecting property and personnel. Replacement of existing switchgear and cable connections with new equipment with higher short-circuit ratings can be technically impossible. The use of Is-limiters reduces the short-circuit current in extensions of existing systems and in new systems. The Is-limiter is capable of detecting and limiting a short-circuit current during the first current rise in less than a millisecond.
11. Arc-faults:
REA arc fault protection relay
REA arc flash mitigation relay uses patented fiber-optic sensor technology that instantaneously detects light from an arc to signal a “trip” to the designated circuit breaker in less than 2.5 ms, minimizing an arc flash incident.
12. Arc-faults:
Upgrade with UFES
UFES, an ultra fast earthing switch, provides detection and grounding of faults in times significantly faster than breaker clearing times, leading to the avoidance of injury and damage and the reduction of production outages. A device as small as an insulator offers enhanced protection for your switchgear by the effects of internal arcs. The UFES arc protection system channels the uncontrolled release of energy by the arc into a solid metal, 3-phase connection to earth potential. The internal arc will be extinguished within an operation time of < 4ms after detection of the fault.

Training


Adequately trained personnel and proper procedures are essential to safe operations



13. Personnel training
Training engineering and technical services provide personnel with a better understanding of their equipment and systems and the safest means to operate them
14. Procedure development
Arc flash studies help to determine the necessary level of protective equipment or clothing (PPE) to be worn by workers in close proximity to potential arcs and also help determine the proper application of any arc flash mitigation equipment to be installed
15. Engineering studies
Engineering studies determine the proper settings and system coordination, while addressing the speed of the system to handle a fault so relays and associated protective devices are set properly in order for the system to react as designed

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