Mersen is pleased to offer several courses to help keep you up to date on the many developments in the electrical industry that are leading to safer workplaces. These courses are taught by veteran experts and are being offered around the country. Trust Mersen as your resource to keep current to protect against electrical hazards that can hurt people, equipment and investments.
The new requirements of NEC 409.22 and 670.5 make it very clear that end users must specify an adequate SCCR (Short Circuit Current Rating) for their industrial control panels and machine control panels. Learn how the choice of the right fuse can easily raise SCCR to safe levels.
This seminar will:
New incident energy equations in the 2018 edition of IEEE 1584 Guide for Performing Arc-Flash Hazard Calculations may provide different results than existing arc flash studies. The new model of IEEE1584-2018 was developed after extensive testing by the IEEE/NFPA Collaboration on Arc Flash Research Project to address issues identified by researchers since its initial release in 2002. The new equations of IEEE1584-2018 require analysts to identify additional variables in a new ten step analysis process. A new technique is available with the new model to handle the energy limiting capabilities of current limiting fuses.
This seminar will:
Increasing concern for arc flash safety has grown to include both operators of electrical equipment as well as electrical workers. Internal arc faults can blow open doors of low voltage equipment including motor control centers (MCC) that have been properly installed. Should this occur when an operator is interacting with the equipment, the worker can very easily be exposed to the hazards of arc flash. To protect workers without arc-rated PPE, ‘arc resistant’ low voltage MCCs have been tested according to an IEEE standard to prove that the MCC contains the hazards of arc flash should an arc fault occur with the doors properly closed. Additionally, many companies are focusing efforts to get lower incident energy levels on equipment that has frequent worker interaction with the doors open. Many are seeking the lowest values that are economically feasible.
Maintaining continuity of power to critical loads requires a system view when deciding on overcurrent protective devices (OCPD) to protect against arc flash. Continuity of service requires that feeder OCPD allow MCC branch devices to clear faults within their zone of protection. If this requires that the upstream feeder OCPD has a delay added to its trip, incident energy levels at the downstream MCC will be increased. Thus, decisions about OCPDs within the MCC can indirectly affect the levels of incident energy at the MCC.
Since current limiting fuses can be coordinated within their short circuit region without any intentional delay, it is possible to dramatically limit the energy delivered to arcing faults without compromising continuity of service because of a short circuit event. Class L and J fuses can limit incident energy throughout the MCC to well below the accepted 2nd degree burn threshold of 1.2 cal/cm2. Properly sized Class J fuses can also minimize damage to faulted branch circuit equipment and provide the best protection of components in the fault path.
This seminar will provide:
Traditional electrical system design approaches and transformer fuse protection practices have yielded arc flash incident energy calculations well above 40 cal/cm2 on the secondary of many power transformers. Many companies use this value as the upper limit for energized work. Consequently these companies insist on outages to perform routine tasks on this equipment. When the equipment is switchgear feeding large processes, the downtime cost of a task such as racking in and closing a power circuit breaker can be tens of thousands of dollars.
This session presents three potential solutions that overcome the shortcomings of traditional primary fuse protection against secondary arc flash events while maintaining all the advantages of primary current limiting fuse protection. The performance tradeoffs of each approach are covered. With the approaches that use overcurrent relays, incident energy calculations are typically reduced to PPE Category 2 or ‘0’.
Selective coordination between overcurrent protective devices (OCPD) is generally desirable and is required by the NEC for circuits related to life safety. Additionally, system downtime is reduced when overcurrent protective devices are selectively coordinated. By limiting an outage to only that circuit which is overloaded or which has been faulted, healthy parts of the electrical distribution system are unaffected.
Achieving coordination between OCPD for short circuits can be challenging. Traditional time-current curve analysis may not accurately portray the degree of selectivity when current-limiting overcurrent protective devices are involved. This training module provides the information needed to ensure your designs comply with NEC requirements.
In the past, voltage surges have largely gone unnoticed. The increased use of electronic devices in residential, commercial, and industrial power systems has exposed the damaging effects of these events. Surge protective devices can mitigate the effects of these transient events. Since 2008 the NEC has mandated installation in certain types of power systems. Additional power systems have been mandated in the 2011, 2014 and 2017 code cycles. Proper selection of devices can allow the consultant or user to protect their sensitive devices and avoid over-protection. In addition, proper installation can avoid device performance issues.
This seminar will:
For more information, email TechnicalServices.EP@mersen.com.