Benefits of Vacuum Interrupter Technology in Medium Voltage Switchgear

Benefits of Vacuum Interrupter Technology in Medium Voltage Switchgear

Posted by Helen Canny on Jun 27, 2019, 9:59:11 AM

The global vacuum interrupter market is projected to reach USD 3.6 billion by 2024 from an estimated USD 2.6 billion in 201.9

Despite the introduction of vacuum interrupter technology dating back to the 1960’s it is still very much a developing technology, with its use in electrical switchgear only gaining significant traction in more recent years. In fact, it is predicted that the largest and fastest growing segment within the vacuum technology market during the forecasted period will be circuit breakers.

How Vacuum Interrupters Work

Vacuum circuit breakers also known as VCBs operate by using a sealed vacuum as an arc quenching medium. VCB’s consist of one fixed and one moving contact which are contained within the vacuum and typically constructed from copper alloys for maximum performance. When these contacts are opened, an arc is produced within the vacuum interrupter due to the ionization of particles between the contact gap. The arc is quickly extinguished as the ions and vapours produced during the arc condense onto the surface of the contracts, resulting in quick recovery of the vacuums dielectric strength. VCB’s are most efficient in medium voltage systems ranging from 11 KV to 33 KV.

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Environmental Benefit

Growing environmental concerns are expected to be a key contributor to growth within the VCB market due the low environmental impact achieved in comparison to traditional medium voltage switching methods.

Prior to the introduction of vacuum interrupter technology, SF6 gas was prevalent in medium voltage arc insulation. However, the recognition of SF6 as a major greenhouse gas with a global warming potential 23,900 times more harmful than CO2 has had a significant impact on efforts to reduce its application – With many governments implementing measures to monitor and control SF6 emissions.

Developed as an alternative to SF6 gas, vacuum technology uses environmentally friendly materials that require no additional gas or oil filling to facilitate arc insulation. The absence of hazardous materials makes it easier for VCB materials to be recycled at the end of their lifecycle. As governments continue to clamp down on the use of SF6 gas, vacuum interrupter technology is fast becoming the more cost-effective option – With reduced environmental regulations and safeguarding practices that businesses are required to comply with.

Enhanced Safety

When an arc occurs in an SF6 gas interrupter, toxic gases are produced and released into the air which can cause irritation to eyes and respiratory systems. As vacuum interrupters do not contain or produce hazardous materials, there is a reduced risk to workers during general maintenance and end of life disposal.

Due to the high dielectric strength of a vacuum, arc voltage will be lower which in turn reduces the arc energy dissipated across the contacts in comparison with other interrupting technologies. This enables vacuum interrupters to quench large fault currents more efficiently, reducing arc flash risk for operators.

Performance

Reliability is the most important factor to consider when choosing a circuit breaker for medium voltage systems.

Vacuum interrupters dissipate low arc energy which results in negligible erosion of the vacuum contacts. Additionally, as the gap between these contacts is small, mechanical operations within the vacuum are much simpler than in other switching devices. These properties contribute to an extended lifespan with very little requirement for maintenance over its entire useful life. The ‘sealed for life’ design ensures that performance properties remain consistence throughout the entire life cycle, due to the airtight vacuum interrupter which eliminates any external influences.

Vacuum switching devices can also generally withstand higher transient recovery voltages than other switching devices. This ensures that the circuit breaker can withstand transient spikes in voltage following arc extinction without reigniting the arc.

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As trends in sustainable power management continue to grow, there are rising pressures from governments for organisations to adopt more sustainable MV switching technologies. Although vacuum technology presents many safety and performance advantages, the low environmental impact is what sets it apart from alternative switching technologies and has prompted significant success within the circuit breaker market.

E+I Engineering’s latest innovation in Medium voltage switchgear has been engineered with the convenience of the end user in mind. The new withdrawable switchgear design allows users to choose between a range of VCB’s which can be integrated into the system interchangeably – Providing one expert system with a lifetime of flexibility.

Topics: MV Switchgear, Medium Voltage Switchgear, Vacuum Interrupter Technology

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