US What feeder automation is
Feeder automation is the use of sensors, remote-controlled switches and controllers along an electricity distribution feeder, so the network can see what is happening on every section and act on it, either automatically or from the control room. A feeder is the medium-voltage line, typically 11 kV in the USA and between about 4 and 35 kV elsewhere, that carries power from a primary substation out to the local transformers serving homes and businesses.
Without automation, a fault on a feeder trips the breaker at the substation and everyone downstream loses supply until crews find the fault, open switches by hand and restore the healthy sections. Feeder automation does most of that work in seconds or minutes. It is one part of the wider field of distribution automation, which also covers substations and the control systems above them.
The devices on an automated feeder
An automated feeder combines switching devices, sensing and a controller at each point, all reporting back over a communications link:
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Reclosers. Pole-mounted circuit breakers that trip on a fault and close again automatically, clearing temporary faults without a long outage.
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Sectionalisers. Switches that count the recloser’s operations and open during a dead interval to isolate a permanently faulted section.
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Remote-controlled switches. Load break switches and ring main switches fitted with motors, so they can be opened and closed remotely.
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Fault passage indicators and sensors. Devices that detect fault current passing them and measure current and voltage along the line.
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Controllers and RTUs. Small computers in a cabinet at each switching point that read the sensors, operate the switch and communicate with the control room.
Local, decentralized and centralized schemes
Feeder automation schemes differ in where the decisions are made. Many networks use more than one type.
| Scheme | Where decisions are made | Communications needed | Typical restore time | Suits |
|---|---|---|---|---|
| Local (device-based) | Each recloser or sectionaliser, from its own settings | None for operation | Seconds, for the sections it protects | Rural overhead lines with simple layouts |
| Decentralized (peer-to-peer) | Controllers along the feeder, sharing data with each other | Fast links between neighboring devices | Seconds to under a minute | Feeders with a few switching points and a tie to another feeder |
| Centralized | Distribution management software in the control room | Reliable links from every device to the control room | Around one to a few minutes | Large meshed networks with many alternative supplies |
Times are indicative and depend on the scheme settings and communications. Centralized schemes have the most complete view of the network; local and peer-to-peer schemes keep working if the link to the control room is lost.
What feeder automation is used for
Fault handling gets the most attention, but an automated feeder does several jobs:
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Monitoring. Live current, voltage and fault data from along the feeder, rather than only at the substation.
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Fault handling. Functions such as FLISR locate a fault, isolate it and restore supply to the healthy sections.
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Reconfiguration and load transfer. Moving load between feeders to relieve overloads or take a section out for planned work.
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Voltage control. Coordinating regulators and capacitor banks to keep voltage within limits as solar and other generation varies.
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Planning. Data that shows where the network needs reinforcement and where new connections can be accepted.
Why networks automate their feeders
Network operators are measured on how often customers lose supply and for how long, usually through indices such as SAIFI and SAIDI, or customer interruptions and customer minutes lost in the USA. Restoring most customers in minutes rather than hours improves both, and avoids sending crews out to operate switches. Automation also gives the visibility that networks increasingly need as rooftop solar, heat pumps and vehicle charging change how feeders are loaded.
Communications and controller hardware
Every automated switching point needs a link back to the control room or to its neighbours. Licensed radio, private LTE, public 4G or 5G and fiber are all used, often as a mix across one network. Our white paper on integrating 4G, LTE and 5G into industrial computers covers the cellular options. On the wire, DNP3 is common in North America, IEC 60870-5-104 is common in Europe, and IEC 61850 is increasingly used for faster peer-to-peer messaging between devices.
The controller at each switching point sits in a small cabinet on a pole or in a ground-mounted kiosk, with no heating or cooling and nobody nearby. It must run for years through frost, summer sun and storms, survive the electrical noise of switchgear, and restart by itself after a power interruption. Fanless DIN rail PCs with serial ports for the switch controls, Ethernet for protection relays and a cellular modem suit that role. Our distribution automation case study shows how fanless controllers fit, and our wide temperature computers cover the climate range. Our explainer on the industrial temperature range sets out what those ratings mean.
Quick answers on feeder automation
Feeder automation: common questions
What is a feeder in power distribution?
A medium-voltage line leaving a substation. It carries power out to the local transformers that supply homes and businesses, and is usually protected by a breaker at the substation end.
What is the difference between feeder automation and distribution automation?
Feeder automation is part of distribution automation. Distribution automation covers the whole distribution network, including substations and control systems; feeder automation covers the lines leaving them.
What is a self-healing grid?
A network that restores itself after a fault. It uses feeder automation and FLISR to isolate the faulted section and reroute supply without waiting for crews.
What is a sectionaliser?
A switch that isolates a faulted section. It cannot break fault current itself, so it counts the upstream recloser’s operations and opens while the line is dead.
Does feeder automation need communications?
Not always. Local recloser and sectionaliser schemes work from their own settings. Peer-to-peer and centralized schemes need reliable radio, cellular or fiber links.
We supply fanless DIN rail and wide temperature computers for feeder automation with the serial, Ethernet and cellular modules fitted as standard, and test each system before it ships. Tell us what the controller connects to and how it reaches the control room, and we will specify the build to match.