The Science Behind Reclosers: How They Protect & Restore Power

Telephone pole with wires and white phone

The Science Behind Reclosers: How They Protect & Restore Power

In the intricate world of electrical distribution, the recloser plays a pivotal role in maintaining the stability and efficiency of our power grids. A recloser is more than a circuit breaker — it’s a sophisticated device designed to quickly detect and interrupt power faults.

Its remarkable ability to automatically reset and restore power sets it apart, should the fault be temporary, thus preventing extended outages and safeguarding the electrical infrastructure. 

In this blog, we’ll delve into the workings of reclosers, uncovering the technology behind them and revealing how they are integral in keeping our lights on.

What are Reclosers?

A recloser is an automated, high-voltage electric switch in power distribution networks. Its primary function is to detect and interrupt momentary faults in the power line that transient issues cause. Examples of transient issues include lightning strikes, interference from small animals, or tree branches touching the lines.

A recloser’s unique, crucial feature is its ability to automatically restore the power flow after interrupting it if the fault is temporary. This capability significantly improves the reliability and efficiency of electrical distribution systems. 

How Does a Recloser Work?

When a fault occurs in the power line, the recloser quickly cuts off the electrical current to prevent damage to the system and reduce the risk of fire. 

After interrupting the current, the recloser waits for a pre-determined period before automatically re-energizing the line. The power is restored if the fault is gone (like if a tree branch fell on the line). But if the fault persists, the recloser will open again. 


A Recloser’s Operation Cycle

Reclosers typically go through opening and closing cycles when a fault is detected. For example, a recloser might try to close after a few seconds. If the fault is still there, it opens again, waits longer, and tries to close again. It will attempt this several times; if the fault persists, the recloser will remain open, and maintenance personnel must take over. 

Types of Reclosers

There are single-phase, three-phase, and triple-single reclosers. Let’s look at each type in more detail. 

1. Single-phase Reclosers

These reclosers protect single-phase lines or a three-phase circuit where the load is primarily single-phase. Single-phase reclosers aren’t that heavy, so they are mounted directly to the pole or substation steel structure. 

You can control a single-phase controller with a hydraulic control integrated inside the recloser tank or an electronic control placed in a separate enclosure. It depends on the recloser design. 

2. Three-phase Reclosers

This system consists of three electrical wires, each carrying an alternating current, with the currents in each wire typically out of phase with the others by one-third of a cycle. Three-phase power systems are widely used because they efficiently transmit power over long distances.

3. Triple-single Reclosers

Three-phase power systems use triple-single reclosers. These reclosers bring a unique approach to handling faults by combining the functions of three single-phase reclosers into one system. This setup allows for more flexible, efficient management of faults on three-phase power lines. Here’s an overview of how triple-single reclosers work:

  • Three-phase power systems: Most electrical distribution systems use three-phase power. The system delivers three separate alternating currents (AC) through three wires, each out of phase with the others.
  • Single-phase reclosers: In a triple-single recloser setup, each phase has its own recloser. This setup means that each of the three wires in the three-phase system is controlled independently by its own recloser.

Types of Recloser Controls

There are two types of recloser controls: hydraulic and electronic. Hydraulic controls, while being the more traditional option, are reliable and effectively fulfill their intended function. On the other hand, electronic controls are a newer innovation, offering rapid response times to ensure optimal operational efficiency.

1. Hydraulic Controls

Hydraulic controls are mostly for single-phase reclosers and some three-phase reclosers. These controls are built into the recloser and work with a trip coil that senses an overcurrent.

When the coil senses the overcurrent, a plunger goes into the coil to trip open the recloser contacts. For large reclosers, oil pumped through different hydraulic chambers or ducts powers this motion. The trip-coil plunger that charges the springs is responsible for the reclosing energy for small reclosers. 

2. Electronic Controls

Electronic controls use electronic components to manage how the device operates. Imagine it like a mini-computer inside the device that’s making the decisions. Here’s how it works:

  • Sensing a problem: When there’s an issue in the power line, like an overload or a short circuit, the electronic control system quickly detects it. 
  • Making fast decisions: Once the problem is detected, the electronic system decides what to do in a fraction of a second. It’s programmed to respond quickly to protect the electrical system.
  • Acting swiftly: Based on its decision, the electronic control will either turn off the power to prevent damage or keep it running if everything’s okay. It does this by sending electrical signals to turn switches on or off, which is much faster than moving fluid around, like in hydraulic systems.
  • Flexibility and precision: Electronic controls are very flexible and can be programmed for different situations. They also make precise adjustments, which helps manage the power system efficiently.
  • Low maintenance: Unlike hydraulic systems, electronic controls don’t have fluids that can leak or need replacing. They generally require less maintenance and are more reliable over time.

So, there you have it. Those are the basics of how reclosers protect and restore power. 

Get Your Recloser from UTB Transformers

If you want to enhance your power network’s reliability and efficiency, look no further than UTB Transformers. We specialize in providing top-tier reclosers equipped with the latest technology to meet your specific needs. 

Whether you require the robustness of hydraulic controls or the precision and speed of electronic systems, our range of reclosers offers the best in performance and reliability. We understand the nuances of power distribution and are committed to delivering solutions that exceed your expectations.

Don’t let your power network be compromised by anything less than the best. Choose UTB Transformers for reclosers that bring together cutting-edge technology and proven reliability. 

Contact UTB transformers today to learn more about our products and how we can help keep your power systems running smoothly and efficiently. With UTB Transformers, you’re investing in the resilience and safety of your entire electrical infrastructure.