TodayÂ’s electrical workers face many challenges when performing daily tasks. Not only must they comply with safety procedures to make sure they are protected from risk, they must face extreme conditions including the environment.
Most concerns revolve around heat and high humidity, and many companies are attempting to address this need with lighter, more breathable garments. But what about the other end of the spectrum — tasks that must be performed in cold weather?
The proper selection of electrical personal protection equipment (PPE) for the worker in a cold weather environment should start with an understanding of the hazards faced by the worker. There are three hazards that must be addressed:
• Shock
• Flash
• Blast
Too often people select their PPE without keeping in mind that these three hazards are always present when working on or around electricity. The selected PPE must integrate properly with each other to ensure a safe working environment.
The focus for electrical protection today is on arc flash, but shock still kills more workers every year than arc flash. Protection from shock should be one of the first things to consider in selecting the proper PPE regardless of weather. Proper voltage-rated gloves, compliant with the requirements of ASTM D120, are a must when working on or near 50 volts or more.
A leather glove protector should be worn at all times over the voltage-rated rubber gloves. These leather protectors offer protection for the voltage-rated gloves from the possibility of punctures or cuts. Plus, they will also help to keep hands warm. The addition of a glove liner, worn under the voltage-rated gloves and leather protectors, will help keep hands warm. These liners come in both silk and cotton materials and help to alleviate any discomfort in any environment.
Complete a hazard risk analysis of your equipment before choosing PPE for flash protection. This will help you select the best PPE for arc flash occurrence. Comfort of the clothing is always second to the protection level. In cold weather, an insulated jacket and bib overall or insulated coverall in a “Duck” fabric are available in flame-resistant (FR) fabrics, for instance.
When selecting PPE, make sure you think of other PPE workers will be wearing to make sure they integrate properly with each other. For instance, the worker will most likely be required to wear voltage-rated rubber gloves and leather protectors. Most companies offer sleeves on their jackets with either an open cuff or with a knit wristlet sewn onto the jacket sleeve.
An open cuff is very difficult to keep covered with a voltage-rated rubber glove due to the cuff being pushed back up on the forearm by not fitting properly inside the rubber glove. The folded cuff inside the glove can also cause discomfort. Cuffs sewn to the end of the sleeve cause a “pillowing” effect of the sleeve. This causes the sleeve to be pushed up on the forearm, separating the sleeve from the voltage-rated rubber glove and exposing the skin.
The best solution is to look for a jacket with the cuff sewn inside the end of the sleeve with an overlap of fabric forming the cuff. This allows for a straight fit into the voltage-rated rubber glove to prevent the jacket from pushing up on the forearm. Adding straps with Velcro will help tremendously to streamline the sleeves for a good integration of gloves and jacket and eliminate the possibility of skin exposure.
There are a few FR-rated fall protection harnesses available on the market today. Face and head protection also depends upon the hazard risk analysis performed on your equipment. As with other PPE, the proper face and head protection for the hazard potential must be worn regardless of weather conditions.
However, there are options that will provide cold weather comfort while complying with the necessary ATPV rating needed. The most obvious would be to wear a double-layer balaclava. (Picture the hood a race car driver wears under his helmet.) There are other tasks which may require the use of a double-layer switching hood in order to be compliant.
In some cases this hood alone may not be warm enough, but adding a balaclava under the hood will significantly increase warmth.
Keeping all three hazards in mind when selecting your PPE is critical to implementing a successful safety plan. With todayÂ’s options in clothing and a better understanding of the workersÂ’ needs, the employer can equip his employees with the proper PPE for the task as well as provide a comfortable solution.
California Duck Curve highlights midday solar oversupply and steep evening peak demand, stressing grid stability. Solutions include battery storage, demand response, diverse renewables like wind, geothermal, nuclear, and regional integration to reduce curtailment.
Key Points
A mismatch between midday solar surplus and evening demand spikes, straining the grid without storage and flexibility.
✅ Midday solar oversupply forces curtailment and wasted clean energy.
✅ Evening ramps require fast, fossil peaker plants to stabilize load.
✅ Batteries, demand response, regional trading flatten the curve.
California's remarkable success in adopting solar power, including a near-100% renewable milestone, has created a unique challenge: managing the infamous "duck curve." This distinctive curve illustrates a growing mismatch between solar electricity generation and the state's energy demands, creating potential problems for grid stability and ultimately threatening to slow California's progress in the fight against climate change.
The Shape of the Problem
The duck curve arises from a combination of high solar energy production during midday hours and surging energy demand in the late afternoon and evening when solar power declines. During peak solar hours, the grid often has an overabundance of electricity, and curtailments are increasing as a result, while as the sun sets, demand surges when people return home and businesses ramp up operations. California's energy grid operators must scramble to make up this difference, often relying on fast-acting but less environmentally friendly power sources.
The Consequences of the Duck Curve
The increasing severity of the duck curve has several potential consequences for California:
Grid Strain: The rapid ramp-up of power sources to meet evening demand puts significant strain on the electrical grid. This can lead to higher operational costs and potentially increase the risk of blackouts during peak demand times.
Curtailed Energy: To avoid overloading the grid, operators may sometimes have to curtail excess solar energy during midday, as rising curtailment reports indicate, essentially wasting clean electricity that could have been used to displace fossil fuel generation.
Obstacle to More Solar: The duck curve can make it harder to add new solar capacity, as seen in Alberta's solar expansion challenges, for fear of further destabilizing the grid and increasing the need for fossil fuel-based peaking plants.
Addressing the Challenge
California is actively seeking solutions to mitigate the duck curve, aligning with national decarbonization pathways that emphasize practicality. Potential strategies include:
Energy Storage: Deploying large-scale battery storage can help soak up excess solar electricity during the day and release it later when demand peaks, smoothing out the duck curve.
Demand Flexibility: Encouraging consumers to shift their energy use to off-peak hours through incentives and smart grid technologies can help reduce late-afternoon surges in demand.
Diverse Power Sources: While solar is crucial, a balanced mix of energy sources, including geothermal, wind, and nuclear, can improve grid stability and reduce reliance on rapid-response fossil fuel plants.
Regional Cooperation: Integrating California's grid with neighboring states can aid in balancing energy supply and demand across a wider geographical area.
The Ongoing Solar Debate
The duck curve has become a central point of debate about the future of California's energy landscape. While acknowledging the challenge, solar advocates argue for continued expansion, backed by measures like a bill to require solar on new buildings, emphasizing the urgent need to transition away from fossil fuels. Grid operators and some utility companies call for a more cautious approach, emphasizing grid reliability and potential costs if the problem isn't effectively managed.
Balancing California's Needs and its Green Ambitions
Finding the right path forward is essential; it will determine whether California can continue to lead the way in solar energy adoption while ensuring a reliable and affordable electricity supply. Successfully navigating the duck curve will require innovation, collaboration, and a strong commitment to building a sustainable energy system, as wildfire smoke impacts on solar continue to challenge generation predictability.
Alberta Power Grid Level 2 Alert signals AESO reserve power usage, load management, supply shortage from generator outages, low wind, and limited imports, urging peak demand conservation to avoid blackouts and preserve grid reliability.
Key Points
An AESO status where reserves power the grid and load management is used during supply constraints to prevent blackouts.
✅ Triggered by outages, low wind, and reduced import capacity
✅ Peak hours 4 to 7 pm saw conservation requests
✅ Several hundred MW margin from Level 3 load shedding
Alberta's energy grid ran on reserves Wednesday, after multiple factors led to a supply shortage, a scenario explored in U.S. grid COVID response discussions as operators plan for contingencies.
At 3:52 p.m. Wednesday, the Alberta Electric System Operator issued a Level 2 alert, meaning that reserves were being used to supply energy requirements and that load management procedures had been implemented, while operators elsewhere adopted Ontario power staffing lockdown measures during COVID-19 for continuity. The alert ended at 6:06 p.m.
"This is due to unplanned generator outages, low wind and a reduction of import capability," the agency said in a post to social media. "Supply is tight but still meeting demand."
AESO spokesperson Mike Deising said the intertie with Saskatchewan had tripped off, and an issue on the British Columbia side of the border, as seen during BC Hydro storm response events, meant the province couldn't import power.
"There are no blackouts … this just means we're using our reserve power, and that's a standard procedure we'll deploy," he said.
AESO had asked that people reduce their energy consumption between 4 and 7 p.m., similar to Cal ISO conservation calls during grid strain, which is typically when peak use occurs.
Deising said the system was several hundred MWs away from needing to move to an alert Level 3, with utilities such as FortisAlberta precautions in place to support continuity, which is when power is cut off to some customers in order to keep the system operating. Deising said Level 2 alerts are fairly rare and occur every few years. The last Level 3 alert was in 2013.
According to the supply and demand report on AESO's website, the load on the grid at 5 p.m. was 10,643 MW.
That's down significantly from last week, when a heat wave pushed demand to record highs on the grid, with loads in the 11,700 MW range, contrasting with Ontario demand drop during COVID when many stayed home.
A heat warning was issued Wednesday for Edmonton and surrounding areas shortly before 4 p.m., with temperatures above 29 C expected over the next three days, with many households seeing residential electricity use up during such periods.
Black Hills Energy Corriedale Wind Farm Expansion earns regulatory approval in Wyoming, boosting capacity to over 52MW near Cheyenne with five turbines, supporting Renewable Ready customers and wind power goals under PUC and PSC oversight.
Key Points
An approved Wyoming wind project upgrade to over 52MW, adding five turbines to serve Renewable Ready customers.
✅ Adds 12.5MW via five new wind turbines near Cheyenne
✅ Cost increases to $79m; prior estimate $57m
✅ Approved by SD PUC after Wyoming PSC review
US company Black Hills Energy has received regulatory approval to increase the size of its Corriedale wind farm in Wyoming, where Wyoming wind exports to California are advancing, to over 52MW from 40MW previously.
The South Dakota Public Utilities Commission approved the additional 12.5MW capacity after the Wyoming Public Service Commission determined the boost was within commission rules, as federal initiatives like DOE wind energy awards continue to support the sector.
Black Hills Energy will install five additional turbines, raising the project cost to $79m from $57m, amid growing heartland wind investment across the region. Corriedale will be built near Cheyenne and is expected to be placed in service in late 2020.
Black Hills said that during the initial subscription period for its Renewable Ready program, applications of interest from eligible commercial, industrial and governmental agency customers were received in excess of the program's 40MW, underscoring the view that more energy sources can make stronger projects.
Black Hills Corporations chief executive and president Linden Evans said: “We are pleased with the opportunity to expand our Renewable Ready program, allowing us to meet our customers’ interest in renewable wind energy, which co-op members increasingly support.
“This innovative program expands our clean energy portfolio while meeting our customers’ evolving needs, particularly around cleaner and more sustainable energy, as projects like new energy generation coming online demonstrate.”
SCE Wildfire Lawsuits allege utility equipment and power lines sparked deadly Los Angeles blazes; investigations, inverse condemnation, and stricter utility regulations focus on liability, vegetation management, and wildfire safety amid Santa Ana winds.
Key Points
Residents sue SCE, alleging power lines ignited LA wildfires; seeking compensation under inverse condemnation.
✅ Videos cited show sparking lines near alleged ignition points.
✅ SCE denies wrongdoing; probes and inspections ongoing.
✅ Inverse condemnation may apply regardless of negligence.
In the aftermath of devastating wildfires in Los Angeles, residents have initiated legal action, similar to other mega-fire lawsuits underway in California, against Southern California Edison (SCE), alleging that the utility's equipment was responsible for sparking one of the most destructive fires. The fires have resulted in significant loss of life and property, prompting investigations into the causes and accountability of the involved parties.
The Fires and Their Impact
In early January 2025, Los Angeles experienced severe wildfires that ravaged neighborhoods, leading to the loss of at least 29 lives and the destruction of approximately 155 square kilometers of land. Areas such as Pacific Palisades and Altadena were among the hardest hit. The fires were exacerbated by arid conditions and strong Santa Ana winds, which contributed to their rapid spread and intensity.
Allegations Against Southern California Edison
Residents have filed lawsuits against SCE, asserting that the utility's equipment, particularly power lines, ignited the fires. Some plaintiffs have presented videos they claim show sparking power lines in the vicinity of the fire's origin. These legal actions seek to hold SCE accountable for the damages incurred, including property loss, personal injury, and emotional distress.
SCE's Response and Legal Context
Southern California Edison has denied any wrongdoing, stating that it has not detected any anomalies in its equipment that could have led to the fires. The utility has pledged to cooperate fully with investigations to determine the causes of the fires. California's legal framework, particularly the doctrine of "inverse condemnation," allows property owners to seek compensation from utilities for damages caused by public services, even without proof of negligence. This legal principle has been central in previous cases involving utility companies and wildfire damages, and similar allegations have arisen in other jurisdictions, such as an alleged faulty transformer case, highlighting shared risks.
Historical Context and Precedents
This situation is not unprecedented. In 2018, Pacific Gas and Electric (PG&E) faced similar allegations when its equipment was implicated in the Camp Fire, the deadliest wildfire in California's history. PG&E's equipment was found to have ignited the fire, and the company later pleaded guilty in the Camp Fire, leading to extensive litigation and financial repercussions for the company, while its bankruptcy plan won support from wildfire victims during restructuring. The case highlighted the significant risks utilities face regarding wildfire safety and the importance of maintaining infrastructure to prevent such disasters.
Implications for California's Utility Regulations
The current lawsuits against SCE underscore the ongoing challenges California faces in balancing utility operations with wildfire prevention, as regulators face calls for action amid rising electricity bills. The state has implemented stricter regulations and oversight, and lawmakers have moved to crack down on utility spending to mitigate wildfire risks associated with utility infrastructure. Utilities are now required to invest in enhanced safety measures, including equipment inspections, vegetation management, and the implementation of advanced technologies to detect and prevent potential fire hazards. These regulatory changes aim to reduce the incidence of utility-related wildfires and protect communities from future disasters.
The legal actions against Southern California Edison reflect the complex interplay between utility operations, public safety, and environmental stewardship. As investigations continue, the outcomes of these lawsuits may influence future policies and practices concerning utility infrastructure and wildfire prevention in California. The state remains committed to enhancing safety measures to protect its residents and natural resources from the devastating effects of wildfires.
Germany's Coal Reliance reflects an energy crisis, soaring natural gas prices, and a nuclear phase-out, as Destatis data show higher coal-fired electricity despite growing wind and solar generation, impacting grid stability and emissions.
Key Points
Germany's coal reliance is more coal power due to gas spikes and a nuclear phase-out, despite wind and solar growth.
✅ Coal share near one-third of electricity, per Destatis
✅ Gas-fired output falls as prices soar after Russia's invasion
✅ Wind and solar rise; grid stability and recession risks persist
Germany is relying on highly-polluting coal for almost a third of its electricity, as the impact of government policies, reflecting an energy balancing act for the power sector, and the war in Ukraine leads producers in Europe’s largest economy to use less gas and nuclear energy.
In the first six months of the year, Germany generated 82.6 kWh of electricity from coal, up 17 per cent from the same period last year, according to data from Destatis, the national statistics office, published on Wednesday. The leap means almost one-third of German electricity generation now comes from coal-fired plants, up from 27 per cent last year. Production from natural gas, which has tripled in price to €235 per megawatt hour since Russia’s invasion in late February, fell 18 per cent to only 11.7 per cent of total generation.
Destatis said that the shift from gas to coal was sharper in the second quarter. Coal-fired electricity increased by an annual rate of 23 per cent in the three months to June, while electricity generation from natural gas fell 19 per cent.
The figures highlight the challenge facing European governments in meeting clean energy goals after the Kremlin announced this week that the Nordstream 1 pipeline that takes Russian gas to Germany would remain closed until Europe removed sanctions on the country’s oil.
Germany has been trying to reduce its reliance on coal, which releases almost twice as many emissions as gas and more than 60 times those of nuclear energy, according to estimates from the Intergovernmental Panel on Climate Change, though grid expansion challenges have slowed renewable build-out in recent years.
Chancellor Olaf Scholz said the opposition CDU bore “complete responsibility” for the exit from coal and nuclear power that formed part of his predecessor Angela Merkel’s Energiewende policies, amid a continuing nuclear option debate in climate policy, which in turn raised reliance on Russian gas. At the beginning of this year, more than 50 per cent of Germany’s gas imports came from Russia, a figure that fell slightly over the opening half of 2022.
But CDU leader Friedrich Merz accused the government of “madness” over its decision to idle the country’s three remaining nuclear power stations from the end of this year, though officials have argued that nuclear would do little to solve the gas issue in the short term.
Electricity generation from nuclear energy has already halved after three of the six nuclear power plants that were still in operation at the end of 2021 were closed during the first half of this year. Berlin said on Monday it would keep on standby two of its remaining three nuclear power stations, a move to extend nuclear power during the energy crisis, which were all due to close at the end of the year.
The German government has warned of the risk of electricity shortages this winter. “We cannot be sure that, in the event of grid bottlenecks in neighbouring countries, there will be enough power plants available to help stabilise our electricity grid in the short term,” said German economy minister Robert Habeck on Monday.
However Scholz said that, after raising gas storage levels to 86 per cent of capacity, Germany would “probably get through this winter, despite all the tension”.
One bright spot from the data was the increase in use of renewable energy, highlighting a recent renewables milestone in Germany. The proportion of electricity generated from wind power generation rose by 18 per cent to 25 per cent of all electricity generation, while solar energy production increased 20 per cent.
Ángel Talavera, head of Europe economics at the consultancy Oxford Economics, said that the success in moving away from gas towards other energy sources “means that the risks of hard energy rationing over the winter are less severe now, even with little to no Russian gas flows”.
However, economists still expect a recession in the eurozone’s largest economy, amid a deteriorating German economy outlook over the near term, as a large part of the impact comes via higher prices and because industries and households still rely on gas for heating.
Separate official data also published on Wednesday showed that German industrial production slid 0.3 per cent between June and July. Production at Germany’s most energy intensive industries fell almost 7 per cent in the five months after Russia’s invasion of Ukraine.
“The demand destruction caused by the surge in prices will still send the German economy into recession over the winter,” said Talavera.
Boeing 787 More-Electric Architecture replaces pneumatics with bleedless pressurization, VFSG starter-generators, electric brakes, and heated wing anti-ice, leveraging APU, RAT, batteries, and airport ground power for efficient, redundant electrical power distribution.
Key Points
An integrated, bleedless electrical system powering start, pressurization, brakes, and anti-ice via VFSGs, APU and RAT.
✅ VFSGs start engines, then generate 235Vac variable-frequency power
✅ Bleedless pressurization, electric anti-ice improve fuel efficiency
✅ Electric brakes cut hydraulic weight and simplify maintenance
The 787 Dreamliner is different to most commercial aircraft flying the skies today. On the surface it may seem pretty similar to the likes of the 777 and A350, but get under the skin and it’s a whole different aircraft.
When Boeing designed the 787, in order to make it as fuel efficient as possible, it had to completely shake up the way some of the normal aircraft systems operated. Traditionally, systems such as the pressurization, engine start and wing anti-ice were powered by pneumatics. The wheel brakes were powered by the hydraulics. These essential systems required a lot of physical architecture and with that comes weight and maintenance. This got engineers thinking.
What if the brakes didn’t need the hydraulics? What if the engines could be started without the pneumatic system? What if the pressurisation system didn’t need bleed air from the engines? Imagine if all these systems could be powered electrically… so that’s what they did.
Power sources
The 787 uses a lot of electricity. Therefore, to keep up with the demand, it has a number of sources of power, much as grid operators track supply on the GB energy dashboard to balance loads. Depending on whether the aircraft is on the ground with its engines off or in the air with both engines running, different combinations of the power sources are used.
Engine starter/generators
The main source of power comes from four 235Vac variable frequency engine starter/generators (VFSGs). There are two of these in each engine. These function as electrically powered starter motors for the engine start, and once the engine is running, then act as engine driven generators.
The generators in the left engine are designated as L1 and L2, the two in the right engine are R1 and R2. They are connected to their respective engine gearbox to generate electrical power directly proportional to the engine speed. With the engines running, the generators provide electrical power to all the aircraft systems.
APU starter/generators
In the tail of most commercial aircraft sits a small engine, the Auxiliary Power Unit (APU). While this does not provide any power for aircraft propulsion, it does provide electrics for when the engines are not running.
The APU of the 787 has the same generators as each of the engines — two 235Vac VFSGs, designated L and R. They act as starter motors to get the APU going and once running, then act as generators. The power generated is once again directly proportional to the APU speed.
The APU not only provides power to the aircraft on the ground when the engines are switched off, but it can also provide power in flight should there be a problem with one of the engine generators.
Battery power
The aircraft has one main battery and one APU battery. The latter is quite basic, providing power to start the APU and for some of the external aircraft lighting.
The main battery is there to power the aircraft up when everything has been switched off and also in cases of extreme electrical failure in flight, and in the grid context, alternatives such as gravity power storage are being explored for long-duration resilience. It provides power to start the APU, acts as a back-up for the brakes and also feeds the captain’s flight instruments until the Ram Air Turbine deploys.
Ram air turbine (RAT) generator
When you need this, you’re really not having a great day. The RAT is a small propeller which automatically drops out of the underside of the aircraft in the event of a double engine failure (or when all three hydraulics system pressures are low). It can also be deployed manually by pressing a switch in the flight deck.
Once deployed into the airflow, the RAT spins up and turns the RAT generator. This provides enough electrical power to operate the captain’s flight instruments and other essentials items for communication, navigation and flight controls.
External power
Using the APU on the ground for electrics is fine, but they do tend to be quite noisy. Not great for airports wishing to keep their noise footprint down. To enable aircraft to be powered without the APU, most big airports will have a ground power system drawing from national grids, including output from facilities such as Barakah Unit 1 as part of the mix. Large cables from the airport power supply connect 115Vac to the aircraft and allow pilots to shut down the APU. This not only keeps the noise down but also saves on the fuel which the APU would use.
The 787 has three external power inputs — two at the front and one at the rear. The forward system is used to power systems required for ground operations such as lighting, cargo door operation and some cabin systems. If only one forward power source is connected, only very limited functions will be available.
The aft external power is only used when the ground power is required for engine start.
Circuit breakers
Most flight decks you visit will have the back wall covered in circuit breakers — CBs. If there is a problem with a system, the circuit breaker may “pop” to preserve the aircraft electrical system. If a particular system is not working, part of the engineers procedure may require them to pull and “collar” a CB — placing a small ring around the CB to stop it from being pushed back in. However, on the 787 there are no physical circuit breakers. You’ve guessed it, they’re electric.
Within the Multi Function Display screen is the Circuit Breaker Indication and Control (CBIC). From here, engineers and pilots are able to access all the “CBs” which would normally be on the back wall of the flight deck. If an operational procedure requires it, engineers are able to electrically pull and collar a CB giving the same result as a conventional CB.
Not only does this mean that the there are no physical CBs which may need replacing, it also creates space behind the flight deck which can be utilised for the galley area and cabin.
A normal flight
While it’s useful to have all these systems, they are never all used at the same time, and, as the power sector’s COVID-19 mitigation strategies showed, resilience planning matters across operations. Depending on the stage of the flight, different power sources will be used, sometimes in conjunction with others, to supply the required power.
On the ground
When we arrive at the aircraft, more often than not the aircraft is plugged into the external power with the APU off. Electricity is the blood of the 787 and it doesn’t like to be without a good supply constantly pumping through its system, and, as seen in NYC electric rhythms during COVID-19, demand patterns can shift quickly. Ground staff will connect two forward external power sources, as this enables us to operate the maximum number of systems as we prepare the aircraft for departure.
Whilst connected to the external source, there is not enough power to run the air conditioning system. As a result, whilst the APU is off, air conditioning is provided by Preconditioned Air (PCA) units on the ground. These connect to the aircraft by a pipe and pump cool air into the cabin to keep the temperature at a comfortable level.
APU start
As we near departure time, we need to start making some changes to the configuration of the electrical system. Before we can push back , the external power needs to be disconnected — the airports don’t take too kindly to us taking their cables with us — and since that supply ultimately comes from the grid, projects like the Bruce Power upgrade increase available capacity during peaks, but we need to generate our own power before we start the engines so to do this, we use the APU.
The APU, like any engine, takes a little time to start up, around 90 seconds or so. If you remember from before, the external power only supplies 115Vac whereas the two VFSGs in the APU each provide 235Vac. As a result, as soon as the APU is running, it automatically takes over the running of the electrical systems. The ground staff are then clear to disconnect the ground power.
If you read my article on how the 787 is pressurised, you’ll know that it’s powered by the electrical system. As soon as the APU is supplying the electricity, there is enough power to run the aircraft air conditioning. The PCA can then be removed.
Engine start
Once all doors and hatches are closed, external cables and pipes have been removed and the APU is running, we’re ready to push back from the gate and start our engines. Both engines are normally started at the same time, unless the outside air temperature is below 5°C.
On other aircraft types, the engines require high pressure air from the APU to turn the starter in the engine. This requires a lot of power from the APU and is also quite noisy. On the 787, the engine start is entirely electrical.
Power is drawn from the APU and feeds the VFSGs in the engines. If you remember from earlier, these fist act as starter motors. The starter motor starts the turn the turbines in the middle of the engine. These in turn start to turn the forward stages of the engine. Once there is enough airflow through the engine, and the fuel is igniting, there is enough energy to continue running itself.
After start
Once the engine is running, the VFSGs stop acting as starter motors and revert to acting as generators. As these generators are the preferred power source, they automatically take over the running of the electrical systems from the APU, which can then be switched off. The aircraft is now in the desired configuration for flight, with the 4 VFSGs in both engines providing all the power the aircraft needs.
As the aircraft moves away towards the runway, another electrically powered system is used — the brakes. On other aircraft types, the brakes are powered by the hydraulics system. This requires extra pipe work and the associated weight that goes with that. Hydraulically powered brake units can also be time consuming to replace.
By having electric brakes, the 787 is able to reduce the weight of the hydraulics system and it also makes it easier to change brake units. “Plug in and play” brakes are far quicker to change, keeping maintenance costs down and reducing flight delays.
In-flight
Another system which is powered electrically on the 787 is the anti-ice system. As aircraft fly though clouds in cold temperatures, ice can build up along the leading edge of the wing. As this reduces the efficiency of the the wing, we need to get rid of this.
Other aircraft types use hot air from the engines to melt it. On the 787, we have electrically powered pads along the leading edge which heat up to melt the ice.
Not only does this keep more power in the engines, but it also reduces the drag created as the hot air leaves the structure of the wing. A double win for fuel savings.
Once on the ground at the destination, it’s time to start thinking about the electrical configuration again. As we make our way to the gate, we start the APU in preparation for the engine shut down. However, because the engine generators have a high priority than the APU generators, the APU does not automatically take over. Instead, an indication on the EICAS shows APU RUNNING, to inform us that the APU is ready to take the electrical load.
Shutdown
With the park brake set, it’s time to shut the engines down. A final check that the APU is indeed running is made before moving the engine control switches to shut off. Plunging the cabin into darkness isn’t a smooth move. As the engines are shut down, the APU automatically takes over the power supply for the aircraft. Once the ground staff have connected the external power, we then have the option to also shut down the APU.
However, before doing this, we consider the cabin environment. If there is no PCA available and it’s hot outside, without the APU the cabin temperature will rise pretty quickly. In situations like this we’ll wait until all the passengers are off the aircraft until we shut down the APU.
Once on external power, the full flight cycle is complete. The aircraft can now be cleaned and catered, ready for the next crew to take over.
Bottom line
Electricity is a fundamental part of operating the 787. Even when there are no passengers on board, some power is required to keep the systems running, ready for the arrival of the next crew. As we prepare the aircraft for departure and start the engines, various methods of powering the aircraft are used.
The aircraft has six electrical generators, of which only four are used in normal flights. Should one fail, there are back-ups available. Should these back-ups fail, there are back-ups for the back-ups in the form of the battery. Should this back-up fail, there is yet another layer of contingency in the form of the RAT. A highly unlikely event.
The 787 was built around improving efficiency and lowering carbon emissions whilst ensuring unrivalled levels safety, and, in the wider energy landscape, perspectives like nuclear beyond electricity highlight complementary paths to decarbonization — a mission it’s able to achieve on hundreds of flights every single day.
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