Transformers are one of the most, if not the most, critical piece(s) of equipment found at a facility. While power and distribution transformers are reliable and have low failures rates, the critical nature of these pieces of equipment, and often little redundancy provided, are key factors that highlight the importance proper monitoring, protection, and contingency planning.
FM Global Property Loss Prevention Data Sheet 5-4, Transformers, has undergone a complete revision effective July 2019. This Data Sheet provides guidance on fire protection for all transformers, as well as electrical protection, testing, maintenance, and operation of specialty transformers only. Specialty transformers include network transformers, rectifier transformers, arc furnace transformers, induction furnace transformers, generator step-up transformers (GSU), series reactors, and shunt reactors. Guidance on smaller transformers smaller than about 5 MVA can be found in FM Global Property Loss Prevention Data Sheet 5-20, Electrical Testing. Amongst many changes, the following key loss prevention items have had revised guidance in the most recent update to FM Global Data Sheet 5-4:
- Online Condition Monitoring
- Equipment Contingency Plan
- Physical Fire Protection
Online Condition Monitoring is an extremely useful predictive and preventative maintenance tool. While it does not justify an overall lack of testing, monitoring can be leveraged to adjust or focus electrical testing and can help define appropriate testing intervals for critical transformers. FM Global recommends that online condition monitoring be provided for high-value or critical transformers having high potential business impact, transformers operating under challenging conditions or environment, and transformers where testing and maintenance intervals need to be extended for business, manpower, or accessibility concerns. Monitoring should be provided for the following parameters:
- Dissolved Gases
- Power Factor for Bushings
- Partial Discharge
- On-load Tap Changer Motor Current
If a transformer breakdown (forced outage) would result in a business or operational exposure that has been deemed to be unacceptable, an Equipment Contingency Plan should be discussed, developed, and maintained in an effort to reduce the exposure created by a potential forced outage.
Included in the contingency plan should be the following:
- Original Equipment Manufacturer (OEM) design information of the transformer
- Process and procedures needed for removing, dismantling, and transporting transformers
- Availability and installation details for long lead-time equipment
- A review of service contracts with OEM and/or vendors
- OEM and/or vendor review and involvement to determine sparing strategies
- Assessment of potential collateral damage to equipment nearby or associated with the electrical system.
Physical Fire Protection is a desirable approach to limit collateral damage to nearby buildings and critical equipment in the event of a transformer failure. The approach differs in relation to protection of indoor vs. outdoor transformers. Fixed protection for outdoor transformers includes installation of automatic water spray sprinkler protection for all transformer surfaces, except areas underneath the transformer. When automatic protection is recommended for indoor transformers, protection options include the following:
- Automatic sprinkler protection
- Foam-water sprinkler system
- Water mist
- Compressed air foam (CAF) system (new)
Compressed air foam is acceptable to supplement a sprinkler/deluge system or as an alternative to emergency drainage. All protection options are recommended to be designed and installed with the appropriate Standards.
As technology, monitoring capabilities, and predictive maintenance become more advanced and more prevalent for a host of critical process and support equipment, transformers are towards the top of the list to leverage this technology and implement practical and reliable testing and maintenance practices. Proper protection, monitoring, and contingency planning will greatly reduce the likelihood and severity of a forced outage or business interruption.
Risk Logic advises on process hazard reviews. Contact Risk Logic with any questions you may have regarding property loss prevention for protection, testing/maintenance, or contingency planning for transformers and other critical equipment.
- FM Global Property Loss Prevention Data Sheet 5-4, Transformers
- FM Global Property Loss Prevention Data Sheet 5-20, Electrical Testing