Improving protection, reducing costs

Every maintenance professional should know how to select the proper fuse for the application.

By Mike Lang

The importance of plant electrical safety has come into sharper focus in recent years. An arc flash incident that injures a worker can easily cost a company several million dollars in regulatory penalties, medical expenses, lawsuits, workers’ compensation, equipment replacement and lost production. The latest versions of NFPA 70E and IEEE 1584 have increased the focus on protecting electrical workers from arc flash hazards and the incident energy to which they could be exposed. OSHA has become better equipped to investigate such incidents. Consequently, upgrading overcurrent protection to include superior current-limiting fuses is a typical plant safety improvement. Properly selected fuses reduce the magnitude of potential arc-flash energies; improperly replaced fuses increase risks to electrical workers and your bottom line.

When added to the substantial pressure to minimize costs and maximize uptime, more plants are discovering the benefits of a comprehensive fuse-protection review. By assessing existing short-circuit protection requirements, consolidating inventories and converting short-circuit protection to UL Class RK1, J and CC fuses with superior current-limiting protection, many plants have found a low-cost, high-impact way to secure their profitability and most important assets: valuable staff members and critical equipment. Properly executed, this process delivers an optimized circuit-protection system, to keep people safe and production online, and it provides better control of spares and replacement routines to ensure continued benefits.

Safety requires the right fuse every time

Put simply, to have optimal short-circuit protection, three factors must be synchronized:

  • What’s needed
  • What’s available
  • Replacement practices

Electrical safety requires that three factors be aligned. Changes occurring today are likely forcing these factors out of synchronization. The desired short-circuit protection occurs only where the three factors complement each other. The more they overlap, the more you achieve optimum short-circuit protection.

The forces

A major change at many facilities is the growing awareness of how short-circuit protection affects electrical worker safety. Arc-flash hazard analyses have clearly shown the need for fuses with lower current-limiting thresholds. The resulting focus on short-circuit protection also led to specifications of fuses with lower I2t values to achieve desired protection levels such as Type 2 for motor starters. Over the years, an expanding variety of spares might have been added, some with very limited applications. Obsolete fuses sometimes remain in storerooms. With increasing pressure to reduce SKUs and associated costs, ensuring the correct fuse is on hand has become more difficult.

The practice of replacing what you took out only works if there are no changes or upgrades. However, in today’s environment, such a strategy could perpetuate a previous error or temporary solution. On-site contractors might be unfamiliar with your facility’s particular needs, applying a generic replacement strategy. With shrinking workforces, employees who lack knowledge of the differences between fuse classes might be inclined to replace a fuse with anything available that fits the holder.

What’s needed, what’s available?

The first step toward an optimal fuse-protection system investigates how well your existing protection philosophy meets your facility’s developing needs. The requirements for greater safety, better protection and less downtime will likely demand revised fuse-protection practices. A review of the latest information on short-circuit protection will be in order.

Whenever a fuse needs to be replaced, the replacement must provide the desired protection level. Assess whether your electrical workers fully understand the differences in protection levels the various classes of UL-listed fuses offer. Having a fuse expert regularly train your electrical workers is helpful and emphasizes your commitment to their safety.

Standardizing on a class of fuse and directing electrical workers in the proper fuse safety practices is not enough to ensure appropriate protection levels with fuse replacement. The final element of your strategy should guarantee the right fuse’s availability whenever needed. Fuse spares consolidation has proved to be highly effective in achieving protection goals. With a consolidation strategy, spares inventory can usually be adjusted downward while still meeting your facility’s evolving protection needs. Obsolete fuses are identified and removed to avoid misuse. Ordering systems also are adjusted to prevent reordering obsolete fuses. Fuse bins in storerooms can then be arranged and labeled in a manner that makes finding the right replacement easy.

Five steps to fuse protection

Developing a streamlined fuse inventory requires goal-setting analysis, planning and implementation. This five-step process can give your plant the safest and most cost-effective fuse-protection systems:

Consultation: Have a fuse expert help you assess the three factors that lead to successful fuse protection. Update appropriate personnel on available fuse protection alternatives. This should include details on arc-flash hazard mitigation, Type 2 protection of motor starters and improved short-circuit ratings. Include a review of the hazards and pitfalls of installing fuses with improper ratings.

Ordering system review: Depending on the facility, fuses can be ordered through a highly automated inventory-replacement system, a manual system, a distributor-run system, or through credit cards used by maintenance personnel. Identify the controls in place to ensure the accuracy and compatibility of the replacement fuse. Assess the system’s database for description quality and part number accuracy.

Storeroom and database reconciliation: This step identifies discrepancies between database descriptions and the fuses in the storeroom bins. Conflicting descriptive information, missing information and fuses with third-party part numbers are the primary concerns. For example, fuses with the OEM part number entered into the database might exclude information on the ratings and actual fuse part numbers that electrical personnel use when searching for replacements. Flag any errors in part numbers and ratings for correction at this stage. Also assess fuse bin organization to ensure that fuses can be located quickly and accurately. This minimizes equipment downtime and the risk of selecting the wrong fuses through expediency.

Comprehensive plan development: Synchronize the ordering system, spares strategy and worker practices to achieve the desired fuse-protection strategy. Start by eliminating obsolete fuse categories as well as duplicate parts by consolidating replacement fuses. Action items include identifying part numbers to be retained and removed, along with their replacements; required ordering system changes and plans for storeroom organization. Develop custom training for electrical workers and storeroom personnel.

Implementation: This is the most critical phase of the process. It’s essential that descriptions be up-to-date, consistent and complete. Information on bin labels must match physical descriptions. Train electrical workers on the new strategy and its reasoning. Storeroom people need to guide workers to the proper replacement, reinforcing the selected strategy. Inform distributors of the safety efforts and make them adapt to your changes. Your inventory must be physically consolidated without errors to avoid jeopardizing fuse-replacement capabilities or increasing inventory levels. All this can be done in a timely fashion at minimum cost. Guidance from a knowledgeable fuse expert and having detailed information ensures an error-free program.

Mike Lang is national industrial account manager for Ferraz Shawmut, Newburyport, Mass. Contact him at (978) 462-6662.

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