- Wildfires pose significant danger to the general public and utilities.
- High voltage surge arresters and fire protection disconnectors minimize fire-producing sparks from utility equipment.
- Passive fire protection solutions like coatings can protect the utility infrastructure.
- Contact prevention products are an effective way to mitigate the risk of power line fires caused by animals.
- Grid monitoring tools provide visibility before, during, and after wildfires.
Severe destruction in the wake of wildfires has received national and international attention over the last few years.
Today, utilities face intense scrutiny and criticism over steps they are taking to prevent future events. New products such as high voltage surge arresters, fire protection disconnectors, fire protection coatings, and contact prevention devices can lower the risk of wildfires around the power infrastructure. Grid monitoring solutions can also play a critical role before, during, and after emergency operations.
A panel of experts from Hubbell Power Systems and Aclara discussed products and solutions designed to address wildfire mitigation.
click presenter image to see bio
Wildfire Mitigation: Products & Solutions
Hubbell offers arrester solutions to mitigate the possibility of an arrester generating sparks and is actively engaged in revisions to the arrester test standards to drive future improvements which consider current market needs.
Wildfires pose significant danger to the general public and utilities.
Over the past decade, the impact of wildfires worldwide has been dramatic:
- The average annual number of wildfires worldwide has been 67,000 and the average acreage burned has been 7 million acres per year.
- In California alone each year over the past five years, on average there have been 144 wildfires and 1,400
- In February 2009, 400 bushfires in Victoria, Australia caused 173 fatalities.
In response, governments worldwide are demanding solutions. At a recent conference, California utilities reported that the top cause of wildfires near power lines is vegetation touching the lines. Other major contributors include dropped conductors and pole or equipment failure. Given their experience with wildfires, Australian utilities have developed effective risk-mitigation programs that represent global best practice.
Figure 1: Wildfire Ignition Data from California Reporting Utilities
“Looking ahead, both utilities and manufacturers are interested in developing standardized test methods for high voltage surge arresters. This work will leverage the Australian standard and CalFire expertise.”
High voltage surge arresters and fire protection disconnectors minimize fireproducing sparks from utility equipment.
High voltage A.C. surge arresters protect vital utility equipment that is costly to replace and often has long lead times to acquire, such as pole top transformers, breakers, or other devices.
Under normal operating circumstance, arresters act as high impedance devices which allow a small amount of current to pass through the devices. When an arrester is exposed to an increase in current, due to lightning or a switching surge, the MOV blocks in the core of the arrester switch into an electrically conductive low impedance state. The surge current is diverted to ground and the arrester limits the voltage across the protected equipment. By limiting the voltage across the arrester and the protected device, the MOV blocks prevent damage from occurring. Following the surge, the arrester returns to a normal high impedance type state.
If a sustained voltage exceeds the capability of the surge arrester, the current that the device is conducting increases significantly. If the arrester short circuits, the system fault current flows through the arrester. When this occurs, hot particles may be expelled which may cause a fire.
Usually distribution surge arresters are equipped with a ground lead disconnector (GLD) which reacts to sudden current increases.
A blank 22 cartridge actuates and breaks the line to ground connection. This removes the shorted product from the system and allows the system to be re-energized. At the same time, arcing and stray particles may be emitted. These must be contained to mitigate the potential fire risk.
Countries and regions have taken different approaches to certifying high voltage surge arresters:
- Australia has developed high voltage surge arrester standards. These are based on IEC standards. Australian standards include a subsection with specific criteria to qualify the spark production class. One commonly used calibration test method to quantify the fire risk is called the “ground paper method.” Australian utilities often require products that meet Class A spark production (zero sparks) based on ground paper testing.
- California relies on the California Power Line Fire Prevention Field Guide. This document outlines procedures to minimize the risk of catastrophic wildfires caused by electrical power lines and equipment. The guide details testing processes and qualified test equipment that meets requirements for CalFire exempt status for electrical equipment. The current edition of the guide was released in 2008, but an updated draft is expected later in 2020.
Hubbell has developed a surge arrester specifically to meet Australian test requirements for Class A. If incandescent particles are emitted from this arrester, they don’t have enough energy to ignite a fuel bed. This product includes insulated line and ground sealing caps which limit the available energized surface area. In some regions of Australia, surge arresters aren’t installed with a GLD.
In response, Hubbell has also developed a fire protection disconnector (FPD) solution. This retrofit option for existing surge arresters is designed to reduce fire-producing sparks. Upon activation, the FPD disconnects the arrester from the line and provides a visual indicator. Additional protection against wildlife interference is provided through an optional wildlife guard.
“No matter what passive fire protection solution you select, you want to make sure it contributes to the lifetime of the pole. The whole point of fire protection in the first place is to avoid the cost of premature replacement.”
Passive fire protection solutions like coatings can protect the utility infrastructure.
Utilities recognize that wooden poles are vulnerable to fire. However, replacing millions of wooden poles with metal or composite ones isn’t realistic from a cost and labor perspective. Reinforcing wooden poles with passive fire protection options is a promising alternative.
To maintain the benefits of wood poles, utilities are choosing to deploy passive fire protection solutions in high risk fire areas, controlled burn zones, and active fire paths. This can reduce the duration and cost associated with power outages after a fire. Coatings and wraps are two options that mitigate fire risks for wooden poles. These products offer different benefits in terms of serviceability, ease of installation and removal, and breathability.
|Ease and Speed of Initial Install||Yes||Yes|
|Easy to Remove and Reinstall After a Fire||Yes||No|
|Allows pole to breathe||Yes||Depends|
Figure 2: Fire Mitigation – Coatings vs. Wraps
Hubbell Power Systems recently introduced a new product called Fire Protection Coating (FPC). This latex intumescent coating is formulated to preserve the structural integrity of wooden utility poles in the event of a fire. When poles are coated with FPC, an intumescent char forms as a reaction to heat or fire, ultimately reducing the risk of catastrophic failure.
Without an available test standard for passive fire protection of wooden utility poles, suppliers and utilities are using a combination of screening methods to validate performance. FPC has been tested using the proposed ASTM method for wooden utility poles. Once an official standard is put in place it is expected to include mechanical loading, weathering evaluation, and a performance baseline for comparing methods.
Fire Protection Coating
Hubbell’s fire protection coating tested to the propsed ASTM method for wood utility poles. Click on the video to see the process.
“According to California utilities, about one in ten of all ignition causes are traced back to animals. A pretty significant number of wildfires are caused directly by animal contact.”
Contact prevention products are an effective way to mitigate the risk of power line fires caused by animals.
Ed LeRouzic reviewed five ways that wildlife can cause fires near power lines:
Animals conduct electricity and are flammable. Dry fur and feathers can be highly flammable in the right situation. If an animal contacts energized equipment, it can ignite and fall onto dry vegetation.
This is a significant problem for North American utilities. Nests are composed of organic matter like twigs and grasses. Birds often build nests near energized components. There is a high risk of nests catching fire and dropping to the ground. Effective mitigation strategies depend on the type of nests, the species involved, and the structures the nests are built on. In some cases, wildlife mitigation products can prevent nesting material from contacting energized components. However, this isn’t always an acceptable substitute for removing the nest.
Close-in faults can cause electrical equipment failures which may result in catastrophic fires.
After an explosion, molten metal or flammable insulating oil is often sprayed onto vegetation below, which can cause a wildfire.
If animals contact a distribution transformer, there may be a fuse expulsion on the disconnect protecting the equipment. Damaged insulation or windings may increase the voltage on the secondary side of the transformer. Secondary system equipment damage can also create fault conditions that cause arcing and conductor damage.
since they support combustion
Even with covers in place, animal contact can occur. If products don’t fit well or aren’t properly applied, equipment is exposed and at risk for contact. If a fault is caused by animal contact, non-fire rated products can ignite themselves and drip flaming material onto vegetation below.
Figure 3: IEEE 1656-2010 suggested flammability test methods.
In 2010, the IEEE released a guideline for evaluating electrical and mechanical performance of wildlife mitigation products.
The guideline calls for sequenced tests. Flammability testing is optional and specified for when nonflammable materials are needed by end users. Two methods are specified for testing flammability: vertical flame test and horizontal burn test.
Hubbell Power Systems offers two product lines for wildlife contact prevention that are V-0 rated and tested in compliance with IEEE 1656:
- Reliaguard: These guards are install-ready and intended for distribution power lines. Reliaguard has been
developed with focus placed on improving retention, ensuring ease of installation and removal, and
- Greenjacket: These site-specific solutions intended for substations focus on a precise fit. Customized guards eliminate contact risk by ensuring complete protection of components. With Greenjacket “no gaps, means no zaps.” Greenjacket solutions come with comprehensive installation instructions to ensure they are applied properly.