Circuit Breaker

15 KV Circuit Breaker: How Does It Work?


The 15 kV circuit breaker is used for the protection of all types of faults due to overcurrent in aerial distribution systems. It is applied to protect transformers, capacitor banks, cables, and secondary distribution lines.

The expulsion circuit breakers are single-pole devices for vertical mounting, specially designed to be used outdoors, giving ample protection to overhead distribution systems, with voltages between 6 kV and 36 kV.

All 15 kV expulsion circuit breakers are equipped with hooks for opening under load using special poles, which are connected in parallel with the fuse tube. Likewise, the devices have an ingenious construction system that guides the fuse holder during the closing, so that it is carried out with great safety, whatever the position of the operator.

The evolution of the 15 kV expulsion cutout has gone from using porcelain to polymeric insulating bases. It consists of three parts, an insulating base, a fiberglass fuse tube with a special coating that helps extinguish the electric arc, and the fuse link itself. They are used for the protection against overcurrents of equipment and elements of the Medium Voltage electrical distribution lines.

Interchangeable type single pole fusible cutout provides overcurrent protection for primary distribution systems. They provide complete protection for all types of electrical faults in overhead distribution systems and equipment and are provided with hooks for the use of portable load break tools.

The circuit breaker provides total protection for all types of overcurrent faults in overhead distribution systems. Its application is to protect against overcurrent faults in transformers, capacitor banks, cables, and secondary distribution lines in nominal currents of 100 amps and with an option up to 200 amps. The term broad fault spectrum protection indicates that the single expulsion fuse cutout interrupts all faults, from the lowest current that blows the fusible link, up to the maximum interrupting capacity.

How Does The 15 kV Circuit Breaker Work?

The 15 kV circuit breaker is one of those that receive the name of an expulsion circuit breaker, because when it melts due to an overcurrent caused by an overload or short circuit, it expels the fuse holder from the base so that the cut is visible, therefore that the point of failure can be located with the naked eye.

When it melts, it hangs upside down from the base of the circuit breaker, normally fixed to the support of the medium voltage line. Using a pole, the fuse holder is recovered with a hook in the form of an eyelet.

Once on the ground we can replace the fused link with a new one, for the preparation of the recommended fuse tables for the protection of transformers and capacitors, we have based ourselves on technical studies and practical cases of use; the recommended types are valid when the ambient temperature, in the place of use, is between -10 °C and 40 °C. Polymeric insulators are composed of an epoxy core with fiberglass and a silicone sheath, anti-vandalism, water-repellent, and without environmental contraindications in their use.

The disconnection operation in the 15 kV circuit breaker is carried out using the opening action of the duct, the gases generated inside the fuse tube help to deionize and extinguish the arc after the fuse has been interrupted.

The disk of the upper cover of the fuse holder is expelled when high interruption currents are present, allowing the evacuation of gases through the upper and lower part of the fuse holder. This double ventilation minimizes mechanical stress, protecting the structure and components of the circuit breaker.

The evolution of the circuit breaker involves replacing the fuse holder with a sectionalized one. Among its advantages we have that it avoids untimely trips, it opens at the third fault and it is not expendable with the consequent savings in travel, no cost for replacement of links, ensuring a better quality of electrical supply, communication via radio with the other two phases (opening three-pole) avoiding receiver breakdowns by remaining in two phases, with GSM module and photovoltaic panel (indicating the exact point of opening).

15 kV Circuit Breaker Parts

The fuse holders have an internal fuse element calibrated so that with a certain current it reaches its melting point and interrupts the passage of electric current through it. To reset it is necessary to replace the fuse element to the fuse holder and reconnect. The fuse holders are generally unipolar operation, in case only one phase melts, it is restored and the other phases do not necessarily have to open.

The circuit breaker shall have hooks that accommodate the tools for cutting under load. In addition, and to facilitate the replacement of the blade by a fuse holder cartridge under tension, it will be provided with supports in its lower part that enable its rapid installation. They will have hook insurance in the closure and insurance against oscillation in the lower limit position.

Its Parts Are:

Porcelain insulator – High mechanical resistance. Also available with polymeric insulator.

Inner Counts – They provide a dual path for the current, independent of the axis of the journal.

Trunnion – The lateral faces of the trunnion are held in wide contact with the hanger to allow alignment of the fuse tube during closure.

But Twist – Secures the Fuse Tube during closing.

Parallel Groove Connector

  • Superior Contacts – stainless steel spring ensures good snap contact.
  • Retaining Hooks – Serve as a guide for the fuse holder during closing.
  • Characteristics of the fuse tube – Made of fiberglass.
  • Hinge joint – Ensures the fall of the fuse holder tube after interruption.
  • Sturdy ferrules – grip the tube at the ends to ensure permanent double-bolted alignment.
  • Trigger – Provides high-speed separation between fuse terminals when the fuse blows, quickly ejecting the wire.

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