What is a Medium Voltage Circuit Breaker, and What Are Its Types?

Electricity is the life wire of most of the physical facilities. It is crucial throughout the world for industries, commercial buildings, business premises, and houses. Under these circumstances, a safe electrical supply and proper distribution of power are crucial. A medium voltage circuit breaker occupies a central place in this system. This is because its function is to protect electrical systems working at medium voltage levels, between 1 kV and 52 kV. This article focuses on the basic aspects of medium voltage circuit breakers, categorization, working principles, testing, and maintenance tips.

What is a Medium Voltage Circuit Breaker?

A medium voltage circuit breaker is one of the most important devices. It controls high currents in the event of overloads or faults. This is used to shield electrical systems from possible hazardous circuits or damages. Hence, they ensure the safety of the operating equipment. Low voltage circuit breakers are designed to be suitable for low voltage transmission. On the other hand, medium voltage circuit breakers are well designed for higher voltage transmission. They are suitable for use in many industrial applications and largely in the distribution of electrical power.

Medium voltage circuit breaker operation can be broken down into the detection of abnormal current conditions, breaker contacts opening to interrupt the current flow, and finally, clearing the arc formed during the interruption. This must happen quickly and accurately to ensure service delivery is not disturbed. 

Medium Voltage Circuit Breaker Types

Below are the most common Medium Voltage Circuit Breaker types.

Air Circuit Breakers (ACB)

Air circuit breakers have air as their arc quenching medium. These are applied in applications where there is frequent switching, and they provide reliability in indoor applications.

Vacuum Circuit Breakers (VCB)

Vacuum circuit breakers are among the most used medium voltage circuit breaker types on the market today. They use a vacuum to interrupt the arc. They offer the best performance and durability and need little or no maintenance. These breakers are particularly applicable to industrial use where maximum dependability is essential.

SF6 Circuit Breakers

These breakers use sulfur hexafluoride gas for arcs. SF6 circuit breakers possess high dielectric strength and can be used both indoors and outside. However, owing to the usage of SF6 gas, the environmental effects of these facilities should be checked.

Oil Circuit Breakers

These use oil as the medium through which an arc is quenched or interrupted. Even though they were once popularly deployed in underground and open-to-air excavations, they have lost precedence due to maintenance issues and improvements made on other breaker types.

Hybrid Circuit Breakers

These MV circuit breakers consolidate two or more technologies of vacuum and either gas or air to produce a circuit breaker that offers better functionality. Many are optimal for challenging electrical systems.

Medium Voltage Circuit Breaker Testing

Testing is crucial for its reliability and continuity. If not detected in time, problems can result in major system problems, and testing discovers such problems in advance. Some common tests include:

Insulation Resistance Test

This test determines the electrical resistance of the insulation to stand the voltage it comes across while in operation without developing leakage or breakdown.

Contact Resistance Test

This test determines how well the breaker contacts perform their resistance since their performance is significant in switching on or off currents.

High-Potential Test

A Hi-Pot test checks the insulating value of this breaker to determine if it can withstand high voltage without a breakdown of the insulation under extreme conditions.

Timing Test

Timing tests determine the rate of operation of the breaker with the contacts required to open and close within the stated time for fault clearance.

Medium voltage circuit breaker testing should be performed periodically to ensure that breakers can function as expected.

Medium Voltage Circuit Breaker Maintenance

Practical medium voltage circuit breaker maintenance prolongs the life span and enhances its efficiency. Key maintenance activities include:

Visual Inspection

Continuous assessment reveals any early indications of the deterioration, corrosion or breakdown of any of the breakers' components.

Cleaning and Lubrication

Dust and dirt, as well as moisture, can influence the breaker's operation negatively. Maintenance by cleaning and application of the right lubricating agent helps to boost performance and reduce malfunction.

Inspection and Replacement

Due to recurrent operation of the breaker interruptions, the contacts usually wear out. The efficiency of these parts demands frequent inspection and replacement when they are worn out.

Testing and Calibration

It is necessary to check breaker performance regularly and maintain the breaker setting and characteristics to achieve the design standards and response time to the fault conditions.

Monitoring Accessories

Relays and sensors that are used together with the breaker should also be tested to be sure that the breaker operates properly.

Preventive maintenance of medium voltage circuit breakers reduces interruption periods, improves safety, and increases the useful life of the equipment.

Advantages of Medium Voltage Circuit Breakers

Enhanced System Protection: Protects equipment by preventing faults from damaging the circuits. 

Operational Efficiency: Promotes enduring energy supply availability and fast fault detection and correction.

Safety Assurance: It minimizes risks of any exposure to hazards that may result in loss of personnel and damage to equipment.

Cost Savings: Eliminates system failure, cutting on the time and cost that may be needed to have it fixed.

Also read: What’s the difference between MCB and MCCB?

Smartshop by Lauritz Knudsen Electrical and Automation

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Whether you require assistance with medium voltage circuit breaker types, operation, maintenance, or testing, Smartshop delivers the expertise and innovation necessary to keep your electrical systems running smoothly. Choose Smartshop for unparalleled reliability and performance in medium voltage circuit breaker solutions.

By understanding the key aspects of medium voltage circuit breakers and their types, operations, testing, and maintenance, you can ensure the optimal performance and safety of your electrical systems.