Differences You Should Know About Vacuum Diodes and Contactors

In recent decades, with the rapid advancement of technology, the need for more complex electrical systems has also increased. This complexity, especially in various industries such as manufacturing and automotive, requires safety and more precise control of electrical components. In this context, vacuum diodes and contactors stand out as two fundamental tools in the management and control of electrical systems.

Vacuum diodes, by providing a mechanism to interrupt or stop the flow of electric current in the event of unforeseen accidents, prevent encountering hazards and damages. These intelligent devices prevent the destruction of electrical systems by unfortunate events and react quickly.

On the other hand, contactors act as electrical control switches and play a role in starting and stopping large electrical devices such as motors. In addition to controlling the flow of current, these devices provide the possibility of automatic or manual control, contributing economically and efficiently to improving the performance of electrical systems.

In this article, a deeper insight into the features and functions of each of these two important elements will be provided. Among the topics to be discussed further in the article are the technical specifications, advantages and limitations, and various applications of these two electrical equipments. This information will assist engineers, technicians, and enthusiasts in the field of electronics and electrical engineering to make informed decisions when selecting and utilizing these fundamental equipments.

Vacuum Diode

A vacuum diode, also known as a circuit breaker, is a highly vital and fundamental equipment in the realm of electrical energy, recognized as a key element in electrical power systems. This equipment facilitates the interruption and connection of high-voltage transmission lines, sub-distribution, and distribution of electricity, quickly disconnecting power lines in the face of unexpected incidents and accidents such as short circuits or sudden current surges.

This equipment is known in French as “Disjoncteur” and in English as “Circuit Breaker” or “Power Switch.” The principle of operation of the vacuum diode is based on the thermionic effect, which operates depending on temperature changes in the electrodes. When the anode electrode is more positive than the cathode electrode, the vacuum diode acts as an electronic barrier and prevents the flow of electric current. If the anode electrode is less positive than the cathode electrode, the vacuum diode does not show any current flow and acts as an open electronic barrier.

Moreover, vacuum diodes play a vital role in protecting high-pressure equipment such as transformers, generators, and power transmission lines. In addition to their immediate functionality, they have proven their effectiveness in maintenance and repairs. Generally, vacuum diodes, due to their importance in ensuring the safety and efficiency of electrical power systems, are regarded as essential components in the energy and power transmission field.

Applications and Advantages of Vacuum Diode

Applications of Vacuum Diode:

1. Power Transmission: Vacuum diodes are used as switches for interrupting and connecting high-voltage power lines in power transmission systems to manage them effectively.

2. Power Distribution: In power distribution networks, vacuum diodes are utilized to interrupt and connect distribution lines and related equipment.

3. Industrial Sector: Vacuum diodes find applications in various industries such as oil and gas, mining, and steel industries for protecting equipment and interrupting electric current in sudden conditions.

4. Railway Lines: In railway systems, vacuum diodes are employed to manage electrical lines and interrupt current flow in case of accidents.

5. Power Generation Systems: In power plants and power generation equipment, vacuum diodes serve as safety and management switches.

Advantages of Vacuum Diode:

1. Performance in Harsh Conditions: Vacuum diodes can operate effectively in harsh environmental conditions such as high temperatures, humidity, and contamination.

2. High Operational Speed: These devices operate quickly and promptly interrupt current in emergency situations.

3. Equipment Protection: Vacuum diodes act as protective systems, preventing damage to equipment and electrical systems.

4. Longevity: These devices have a long lifespan and high stability, making them economically beneficial.

5. Low Maintenance Requirement: Due to their simple structure and use of vacuum technology, vacuum diodes require minimal maintenance and servicing.

Types of Circuit Breakers

Vacuum Circuit Breaker:

Vacuum circuit breakers utilize vacuum (or void) to extinguish electrical arcs. These breakers have a simpler structure compared to other types and operate very quickly. Their long lifespan, minimal maintenance requirement, and ability to operate in various temperature and pressure conditions are important features of vacuum circuit breakers. Due to these characteristics, vacuum circuit breakers are widely used as primary options for power distribution and transmission systems in various industries.

SF6 Gas Circuit Breaker:

SF6 gas circuit breakers use sulfur hexafluoride (SF6) gas as an insulating medium. This gas has excellent insulating properties and vaporizes rapidly due to its very low boiling point, extinguishing electrical arcs quickly. SF6 gas circuit breakers are used extensively in power distribution systems and substations due to their highly reliable performance and wide range of applications.

Air Circuit Breaker:

Air circuit breakers use air as an insulating medium to extinguish electrical arcs. These breakers have a simple structure and are generally used for less sensitive applications that do not require rapid and precise operation in the power grid. However, they are used as an economical and safe option for situations where high-power current interruption is not needed.

Air Blast Circuit Breaker:

Air blast circuit breakers use compressed air jets to cool and extinguish electrical arcs. These breakers have very fast operation and are typically used in high-voltage networks and automatic connections. They are considered the best option in terms of immediate intervention capability.

Minimum Oil Circuit Breaker (MOCB) or Semi-Oil Circuit Breaker:

Minimum oil or semi-oil circuit breakers use a mixture of oil and gas to extinguish electrical arcs. These circuit breakers are used in environmentally sensitive areas due to their minimal oil consumption and less harmful effects compared to conventional oil circuit breakers.

Oil Circuit Breaker:

Oil circuit breakers use oil as an insulating medium to extinguish electrical arcs. Due to the good thermal properties of oil, these circuit breakers perform well in various temperature conditions. However, due to the damaging effects of fire and high oil consumption, their use is limited, and instead, preference is given to minimum oil circuit breakers.


ABB (ABB Group):

ABB is a leading company in the field of electrical and automation technologies, operating in over 100 countries worldwide. The company is extensively involved in power distribution, transmission systems, and industrial automation equipment. ABB’s circuit breakers offer high efficiency, advanced technologies, and meet international standards.


Siemens is one of the top companies in the technology and energy sector, operating in over 190 countries worldwide. The company is engaged in the production of electrical products, industrial automation, and energy management systems. Siemens circuit breakers are highly trusted due to their high-quality construction, long lifespan, and reliability.

Schneider Electric:

Schneider Electric is a leading player in the energy management and automation industry, operating in over 100 countries worldwide. The company is renowned for its production of circuit breakers and electrical protection equipment. Schneider Electric’s circuit breakers stand out for their reliance on advanced technologies, high efficiency, and compliance with industry standards.

General Electric (GE):

General Electric (GE) is one of the pioneering companies in the field of electrical and electronic product manufacturing. With a presence in over 170 countries worldwide, the company is engaged in the production of electrical equipment, energy systems, and advanced technologies. GE’s circuit breakers, benefiting from its long history in the electrical industry and utilization of modern technologies, boast high quality and reliable performance.


Eaton is a leading company in the field of electrical and hydraulic technology, operating in more than 170 countries. The company is known for its production of electrical products, automation systems, and equipment related to electric motor power. Eaton’s circuit breakers, leveraging modern technologies and intelligent solutions, are recognized as one of the top choices in the global market

Mitsubishi Electric:

Mitsubishi Electric is one of the top Japanese companies in the technology and energy sector, with operations in over 120 countries worldwide. The company is famous for its production of electronic products, industrial automation, and electrical equipment. Mitsubishi Electric’s circuit breakers, characterized by precision engineering and the use of advanced technologies, offer high quality and reliable performance.

Vacuum Contactor

A vacuum contactor is a vital electromechanical device in electrical circuits with medium voltage and high current. This device is used for controlling and managing electrical currents in power systems. Unlike old manual switches that could face difficulties in handling large currents, vacuum contactors utilize a vacuum space to interrupt and establish electrical currents.

With a reliable and precise operating system, the ability to manage large currents, and the absence of electric arcs or sparks during operations, this device is recognized as an advanced solution in the electrical industry. Vacuum contactors are constructed from resilient and insulating materials such as copper and iron alloys. Equipped with vacuum chambers, they feature characteristics such as arc suppression, silent operation, and long lifespan.

Overall, vacuum contactors, as an essential component in modern electrical systems, provide reliable performance and extensive capabilities through the utilization of advanced technologies.

Application and Advantages of Contactors

Applications of Vacuum Contactors:

Vacuum contactors are used as a fundamental element in various industries and systems for managing electrical currents. Some of their applications include:

1. Power Industry: In power distribution, vacuum contactors are utilized to control various equipment such as motors, capacitors, and other devices.

2. Automotive: In the electrical systems of vehicles, especially in controlling motors and auxiliary equipment, vacuum contactors are employed.

3. Oil and Gas Industries: In hazardous environments and harsh conditions, vacuum contactors, due to their robust performance and resistance capabilities against adverse weather conditions, are used to control necessary equipment.

Advantages of Vacuum Contactors:

Reliable Performance: By utilizing a vacuum space for interrupting and establishing electrical currents, vacuum contactors offer highly reliable performance and prevent electric arcs.

Long Lifespan: The use of durable materials and resistance to wear and tear results in vacuum contactors having a long lifespan.

Control of Large Currents: These devices have the capability to manage large currents, making them suitable for controlling heavy loads and high-power motors.

Protection Against Arcing and Fast Switching: The vacuum space prevents the generation of sparks during switching, ensuring fast and silent operations.

Low Maintenance Requirements: Due to their simple structure and resistance to wear, vacuum contactors require minimal maintenance.

Types of Contactors

Electromagnetic Coil Vacuum Contactors:

Description: These contactors utilize electromagnetic coils to excite and control contacts. By creating an electromagnetic field, these coils attract contacts and establish connections between them.

Application: In industries such as automotive, automation, and electrical.

Vacuum Contactors with Vacuum Interrupter:

Description: This type features a vacuum interrupter housed within a vacuum chamber, capable of interrupting and establishing electrical currents.

Application: In power distribution stations, petrochemical industries, industrial automation systems, etc.

Single-phase and Three-phase Vacuum Contactors:

Description: They can be designed as single-phase or three-phase, depending on the application and requirements.

Application: In power distribution systems, conversion and distribution stations, both small and large industries, etc.

Vacuum Contactors with Various Voltage and Current Ratings:

Description: These contactors are designed with different voltage and current ratings to suit various application needs.

Application: In industrial systems, industrial control and automation, etc.

Vacuum Contactors with Different Chambers:

Description: The vacuum chamber of vacuum contactors can be made of various materials and sizes, depending on the requirements and applications.

Application: In power distribution systems, power stations, protection and control systems, etc.

Vacuum Contactors with Special Features:

Description: Some of these contactors have special features such as resistance to shock and vibration, high mechanical strength, or the ability to operate in specific conditions.

Application: In specialized industries such as military, aerospace, maritime, medical, etc.



A reputable brand in the production of electrical equipment and automation.


One of the largest companies in the world manufacturing electrical and electronic equipment.

Schneider Electric:

Specializes in producing products related to energy management and industrial automation.


Active in the production of electrical equipment and energy management.

Mitsubishi Electric:

A Japanese company specializing in the production of electronic and electrical products.


A reputable Japanese company active in the field of electrical and electronic equipment.

Rockwell Automation:

Manufacturer of industrial automation equipment and energy management.

General Electric (GE):

One of the largest and most reputable companies in the electrical and energy industry.

Difference Between Vacuum Diode and Vacuum Contactor

Primary Function:

Vacuum Diode: Primarily used for interrupting electric current in an electrical circuit. Vacuum diodes act as electronic switches, opening and closing, and are used in regulating electric current and applications requiring rapid switching mechanisms.

Vacuum Contactor: In contrast to vacuum diodes, vacuum contactors are utilized as robust switches to control electric current in large and powerful circuits. These devices mechanically interrupt and connect electric current, primarily employed in power distribution systems and motor control.

Structure and Design:

Vacuum Diode: Constructed as an electronic diode, it comprises two metal electrodes within a vacuum chamber. Its operation is based on the thermionic emission effect.

Vacuum Contactor: This device features one or more control coils to activate and control the contacts. Typically, electromagnetic or solenoid wiring is employed to move the contacts.


Vacuum Diode: Commonly used in sensitive electrical circuits, current regulation circuits, and certain electronic devices.

Vacuum Contactor: Utilized in power distribution systems, motor control, transformers, and other power systems to interrupt and connect large currents.

Electric Current Carrying Capacity:

Vacuum Diode: As an electronic diode, vacuum diodes typically carry lower electric currents.

Vacuum Contactor: Due to their use in power systems, vacuum contactors are capable of carrying very high currents.

Service Life:

Vacuum Diode: Diodes are primarily used in electronic circuits with applications sensitive to speed, and may have a shorter service life.

Vacuum Contactor: As an industrial device, vacuum contactors are mainly intended for use in industrial and harsh environments, generally having a longer service life.


Vacuum Diode: Due to their simpler structure and specific applications, vacuum diodes may have lower costs.

Vacuum Contactor: As they are used in power and industrial systems, vacuum contactors may have higher costs. However, this cost is justified by their longer service life and high performance.

In this discussion on the difference between vacuum diodes and vacuum contactors, two main devices in the electronics and electrical industry have been examined. The vacuum diode, functioning as an electronic diode, is constructed based on the principle of thermionic emission and is used to regulate electric current in electronic circuits. This device controls electric current by creating an electronic barrier in the vacuum space between two electrodes. Among the advantages of vacuum diodes are high precision, reliable performance, and the absence of regular maintenance requirements.

On the other hand, vacuum contactors are used as electromechanical devices for controlling electric current in power circuits. These contactors employ different operational mechanisms such as electromagnetic coils or vacuum interrupters to interrupt and connect electric currents. Vacuum contactors are known for features such as precise switching, resistance to various environmental conditions, and long service life.

With these interpretations, it can be concluded that vacuum diodes and vacuum contactors each have different features and applications, making them suitable choices depending on the requirements of the circuit in use. Vacuum diodes are more suitable for electronic applications and sensitive circuits, whereas vacuum contactors are used for controlling electric currents in power and industrial circuits.

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