Manage Your Power to Enhance Safety, Improve Uptime
Second of Two Parts
In the summer issue, Part One examined a range of components engineered to improve safety and reliability. Part Two will explore a range of electrical distribution solutions engineered to improve the safety and reliability of upstream pumping operations. Oil and gas operations run in harsh, demanding environments, all of the time and around the world. To keep running, they require safe, reliable and efficient power.
Safety first. Personnel and equipment safety is paramount and even more so in offshore environments. At the same time, the cost of a power outage is enormous. Systems are expected to be up and running all the time. A range of electrical equipment is engineered to meet the rigorous application demands of upstream operations, and experienced service teams can customize solutions and upgrade existing systems to meet today’s demands and standards.
Part Two focuses on the electrical distribution solutions engineered to enhance safety, improve uptime and increase efficiency while meeting space constraints—which can be more limited in offshore applications.
Arc Flash Safety Standards—in Brief
The risk of an arc flash event is real, and it can instantaneously generate temperatures about four times the temperature of the sun. An arc flash is associated with the explosive release of energy caused by an electrical arc—due to either a phase-to-ground or phase-to-phase fault. This kind of fault can be the result of many factors—a dropped tool, accidental contact with electrical systems, a buildup of conductive dust, corrosion or improper work conditions.
Recent standards and design requirements—National Fire Protection Agency (NFPA) 70E—are applicable to personnel who install, maintain or repair electrical systems. The purpose of NFPA 70E is to provide guidelines intending to limit injury to onset second-degree burns.
Motor Control, Engineered Arc Flash Protection
Motor control centers (MCCs) are routinely accessed for a variety of reasons—connecting or disconnecting starters or feeders, adjusting trip settings, replacing fuses, adding motor loads and general troubleshooting. To make adjustments, access to the interior of the unit buckets is required.
This means that the motor control center does not provide the highest level of personnel protection. Maintaining a deadfront barrier, such as a unit closed while connecting and disconnecting MCC starter or feeder units and providing insulated components or connections, significantly reduces the possibility of an arc-flash incident.
Testing conducted by the Institute of Electrical and Electronics Engineers (IEEE) 1584P can be conducted to verify that closed-door operation provides a considerably lower risk category than the risk Category 3 assigned by the NFPA 70E Table 130.7 (c)(9)(a) for insertion and removal of MCC units. Beyond thermal hazards, a closed door provides better protection from shrapnel, noise, gases and blinding light. Remote-operated racking devices are available so that an operator may advance and retract the stabs from upward of 15 feet.
There are MCCs engineered to protect equipment and personnel from the danger of an arc flash. Minimizing the impact and exposure to higher PPE levels in industrial environments means increased uptime and enhanced personnel safety. These motor control centers lower the probability of creating a short circuit phase-to-phase or phase-to-ground, while lowering the probability of electrical shock and reducing incidents of arc flash energy during maintenance. The design focuses on:
- Enhancing safety by improving overall arc flash safety through training, labeling, analysis and solutions that reduce exposure to dangerous situations
- Avoiding costs by reducing or eliminating unplanned downtime, equipment damage and enhancing safety through improved safety practices
- Mitigating risk by meeting or exceeding the standards from NFPA 70E and IEEE 1584P.
Space-Saving Integrated Control Equipment
Fundamentally, adjustable frequency drives regulate a motor’s speed to closely match application requirements—so only the energy that is needed for an application is used. Medium- and low-voltage drives gradually accelerate the motor or pump—improving system reliability by protecting assets, extending equipment life and reducing wear and tear.
Often, adjustable frequency drives are installed and treated as independent, stand-alone systems. Whereas standard, full-voltage starters are typically contained within the same medium-voltage control gear lineup and fed by a common bus—saving space and streamlining installation.
Recently, drive designs have begun to integrate additional components, including incoming line isolation contractors.
This means designs are more compact with no need for an additional drive input structure. Further space can be saved by integrating the adjustable frequency drive into a lineup by connecting associated main breakers and output bypass contactors under a common bus—minimizing its footprint on a platform.
When operator safety is a concern, arc-resistant switchgear should be considered. It is designed to channel arc energy inside the equipment, away from personnel and out the top of the switchgear. Low- and medium-voltage switchgear is used to protect, control and monitor distribution systems and to protect operating and maintenance personnel from dangerous arcing faults.