Substations without transformers are called switchyards. A switchyard is remotely operated to re-route power supplies where there is an immediate or critical need.
Once the voltage has been lowered to 66, 33 or 11 kV, the electricity is moved through to large industrial customers or the distribution network where it is taken to homes and businesses. Light poles provide lighting for crews that might need to attend the site in the event of a fault. Surge arrestors protect equipment within the substation from any voltage spikes on the transmission lines.
Line disconnectors allow transmission lines and equipment within the substation to be safely isolated for maintenance work. Voltage and current transformers measure voltage and current entering and moving through the substation. Circuit breakers are automatic switches that interrupt electrical flow to de-energise equipment and clear faults.
Weather stations provide real time information about localised conditions which could affect the safe and reliable operation of the transmission network. Many of those challenges are overcome at facility which, at first glance, often looks like a chaotic and dangerous mess of wires and equipment, but which actually serves a number of essential roles in our electrical grid, the substation.
In reality, the electricity normally makes its way through a series of discrete steps on the grid normally divided into three parts: generation, or production of electricity; transmission, or moving that electricity from centralized plants to populated areas; and distribution, or delivering the electricity to every individual customer. If you consider the power grid a gigantic machine and many do , substations are the linkages that connect the various components together.
One of the cool parts about our electrical infrastructure is that most of it is out in the open so anyone can have a look. Those roles depend on which parts of the electrical grid are being connected together and the types, number, and reliability requirements of the eventual customers downstream. And the first and often simplest of these roles is switching. The general layout of a substation consists of some number of electric lines called conductors if you want to fit in with the electrical engineers coming into the facility.
These high voltage conductors connect to a series of some or many pieces of equipment before heading out to their next step in the power grid. As a junction point in the grid, a substation often serves as the termination of many individual power lines. This creates redundancy, making sure that the substation stays energized even if one transmission lines goes down.
But, it also creates complexity. The connections to these various devices are called buses, often rigid, overhead conductors that run along the entire substation. The arrangement of the bus is a critical part of the design of any substation because it can have a major impact on the overall reliability.
Like all equipment, substations occasionally have malfunctions or things that simply require regular maintenance. To avoid shutting down the entire substation, we need switches that can isolate equipment, transfer load, and control the flow of electricity along the bus.
At high voltages, even air can act like a conductor, which means even if you create a break in a line, electricity can continue flowing in a phenomenon known as an arc. Not only does arcing defeat the purpose of a switch, it is incredibly dangerous and damaging to equipment. So, switching in a substation is a carefully-controlled procedure with specially-designed equipment to handle high voltages. Disconnect switches are often just called switchgear in addition to the equipment that serves another important role in a substation: protection.
I mentioned earlier that much of our electrical infrastructure is exposed and out in the open. From lightning strikes to rogue tree limbs, windstorms to squirrels, grid operators contend with so many threats to their infrastructure on a day by day basis. When something causes a short circuit on the power grid, also called a fault, it can severely damage power lines and other equipment. Not only that, because of the overwhelming complexity of the power grid, faults can and do cascade in unexpected and sometimes uncontrollable ways, leaving huge populations without power for hours or days.
Many of the ways we protect equipment from faults are handled at a substation. One of the most common types of electrical fault is a short circuit to ground.
This type of fault creates a low-resistance path for current to flow and leads to an overload of power lines and equipment. The PUD generally needs a minimum of one acre of flat land for a substation. This one acre includes a set back and the fencing that surrounds the actual substation equipment.
The substation itself has about a half-acre footprint. Q: Is there audible sound from a substation? A: The main noise heard from a substation is a hum coming from the transformer. This hum is the same type of hum, only greater as the transformer is bigger, to other transformers or streetlights, found on most street corners.
Modern substation transformers are quieter than transformers built just a few years ago — often 10 decibels dB quieter for an equivalent transformer due to recent advances. Chelan PUD purchases new transformers that meet this lower sound level. A typical new substation transformer will produce approximately 65 dB of noise measured at 2. This is about the loudness of a newer standard residential outdoor air conditioning unit.
The sound level diminishes the further away from the sound producing source. At the substation perimeter fence the sound level has dissipated to lower levels. Q: What type of mitigation can a neighborhood expect to help improve the aesthetics of a substation? A: When planning the construction of a substation, PUD staff will work with the community to discuss design and landscaping alternatives.
These include:. A: There are two reasons Chelan PUD has not chosen to build underground transmission - higher costs and the complexity of the engineering and maintenance. In addition to high initial construction costs compared to above ground transmission, it also would require Chelan PUD to create a new division internally, to hire additional engineering staff and trained maintenance crews, and to stock spare parts and other assets to maintain a limited amount of underground transmission.
Creating this business unit in the timeframe to construct needed substations and transmission lines in the near term is not feasible at this time. Q: What are the health risks of living near a substation? A: Electromagnetic fields EMF are the invisible fields that surround all electrical equipment and power lines. Electric fields exist everywhere we live or work.
Any electric line or appliance emits both electric and magnetic fields, which combined create EMFs. All things electrical, from your toaster to high voltage power lines, are surrounded by EMFs. These fields drop off rapidly with distance from the source.
There are conflicting research results on whether EMFs affect human health. These studies have used a variety of approaches to explore the potential health effects of EMF. Scientific evidence does not support a cause-and-effect relationship between EMF exposure and health risks. People get most of their EMF exposure from electrical wires along the street and from wiring in their homes. People also get short-duration higher field exposures when they pass close to electrical appliances see table below.
Outside the home, people can experience EMFs from cell phones, in schools, industrial warehouses, offices, electric vehicles, etc. From the electricity system, high-voltage power lines produce higher fields than substations.
As a whole, not many people live within yards of a high-voltage power line. More people live close to a substation of one sort or another, but even if you live very close, the level of exposure is minimal. A Gauss meter measures the EMF levels of electronic devices and equipment. The Gauss meter measures in units called milligauss, abbreviated mG.
Q: What are the potential environmental concerns at a substation and how are they addressed by the PUD? A: The primary materials in substations are metals.
The power transformer is filled with non-toxic and non-hazardous mineral oil that is used for cooling and electrical insulating.
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