{"id":3342,"date":"2026-09-03T16:49:43","date_gmt":"2026-09-03T08:49:43","guid":{"rendered":"http:\/\/www.dumostar.com\/blog\/?p=3342"},"modified":"2026-09-03T16:49:43","modified_gmt":"2026-09-03T08:49:43","slug":"what-is-the-difference-between-a-sealed-and-an-open-type-vacuum-relay-4d8a-74dfe2","status":"publish","type":"post","link":"http:\/\/www.dumostar.com\/blog\/2026\/09\/03\/what-is-the-difference-between-a-sealed-and-an-open-type-vacuum-relay-4d8a-74dfe2\/","title":{"rendered":"What is the difference between a sealed and an open – type Vacuum Relay?"},"content":{"rendered":"

In the realm of electrical engineering, vacuum relays play a crucial role in various applications, from telecommunications to high – energy physics experiments. As a seasoned supplier of vacuum relays, I often get asked about the differences between sealed and open – type vacuum relays. In this blog post, I’ll delve into the technical aspects, applications, and advantages of each type to help you make an informed decision when choosing the right vacuum relay for your needs. Vacuum Relay<\/a><\/p>\n

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1. Technical Structure and Working Principles<\/h3>\n

Sealed Vacuum Relays<\/h4>\n

Sealed vacuum relays are designed with a hermetically sealed enclosure. This enclosure is typically made of glass or ceramic, which provides excellent insulation and protection against external contaminants. Inside the sealed chamber, there is a vacuum environment, usually at a pressure of around (10^{-4}) to (10^{-6}) torr. The contacts are placed within this vacuum, and when the relay is energized, an electromagnetic field is created that causes the contacts to move and make or break the electrical connection.<\/p>\n

The hermetic seal ensures that the vacuum is maintained over a long period. This is important because a stable vacuum environment is essential for the proper functioning of the relay. It helps to prevent arcing between the contacts, which can cause damage and reduce the lifespan of the relay. Additionally, the sealed design protects the internal components from moisture, dust, and other environmental factors, making sealed vacuum relays highly reliable in harsh operating conditions.<\/p>\n

Open – type Vacuum Relays<\/h4>\n

Open – type vacuum relays, on the other hand, do not have a hermetically sealed enclosure. The contacts are exposed to the surrounding environment, although the relay is still designed to operate in a relatively clean and dry atmosphere. The vacuum in an open – type relay is created and maintained through a pumping mechanism, which continuously removes air and other gases from the vicinity of the contacts.<\/p>\n

When the relay is activated, the contacts move in a similar way to those in a sealed relay. However, because the contacts are not protected by a hermetic seal, they are more vulnerable to contamination. This means that open – type vacuum relays require more careful handling and maintenance to ensure optimal performance.<\/p>\n

2. Electrical Performance<\/h3>\n

Contact Resistance<\/h4>\n

In sealed vacuum relays, the contact resistance is generally lower and more stable. The hermetic seal protects the contacts from oxidation and contamination, which can increase contact resistance over time. This low and stable contact resistance is crucial for applications where high – precision electrical signals need to be transmitted, such as in measurement and test equipment.<\/p>\n

Open – type vacuum relays may have slightly higher contact resistance, especially if they are not properly maintained. The exposure of the contacts to the environment can lead to the formation of a thin layer of contaminants on the contact surfaces, which can increase the resistance. However, with proper cleaning and maintenance, the contact resistance of open – type relays can be kept within an acceptable range for many applications.<\/p>\n

Dielectric Strength<\/h4>\n

Sealed vacuum relays typically have higher dielectric strength compared to open – type relays. The hermetic seal provides an additional layer of insulation, which helps to prevent electrical breakdown between the contacts and the surrounding environment. This makes sealed vacuum relays suitable for high – voltage applications, such as in power distribution systems and high – energy particle accelerators.<\/p>\n

Open – type vacuum relays have a lower dielectric strength because the contacts are exposed to the environment. However, they can still be used in medium – voltage applications where the risk of electrical breakdown is relatively low.<\/p>\n

Arcing and Switching Performance<\/h4>\n

One of the key advantages of vacuum relays is their ability to suppress arcing during switching operations. Sealed vacuum relays are very effective in this regard. The vacuum environment inside the sealed enclosure helps to quickly extinguish the arc, which reduces wear and tear on the contacts and extends the lifespan of the relay. This makes sealed vacuum relays ideal for high – frequency switching applications, such as in radio frequency (RF) circuits.<\/p>\n

Open – type vacuum relays also have good arcing suppression capabilities, but they may be more prone to arcing if the surrounding environment is not clean or if the vacuum is not properly maintained. In applications where frequent switching is required, the reliability of open – type relays may be affected by the increased risk of arcing.<\/p>\n

3. Applications<\/h3>\n

Sealed Vacuum Relays<\/h4>\n