How Does a Medium Voltage VCB Improve Electrical Safety

The medium voltage VCB (Vacuum Circuit Breaker) is a critical component for the safety and protection of power distribution within medium voltage electrical systems (10kV - 35kV). It is more effective than older oil and gas extinguishing breakers since the VCB employs a vacuum chamber to interrupt fault currents, isolating the faulty section of the grid very quickly. They are extremely dependable in difficult conditions such as urban power grids, industrial plants, and commercial complexes. GPSwitchgear is a leader in the optimization of medium voltage VCB design for improved safety and its real-world applications. Below are several ways the medium voltage VCB enhances electrical safety.

Medium-Voltage VCB Focuses on Quickly, Effectively, and Safely Preventing Arc Hazards

In medium voltage systems, electric arcs top the list of dangerous hazards. To put things into perspective, they generate a searing 20,000 degrees Celsius and can melt metals, damage insulations, and even cause fires and explosions. The Medium Voltage VCB combines the best of both worlds by incorporating the amazing arc-extinguishing properties of a vacuum. When something goes wrong, such as a short circuit, the medium voltage VCB quickly separates its contacts in a vacuum chamber. Thanks to the vacuum environment, the formation of ionized gases (which sustains arcs in other breakers) is erased, extinguishing the arc in 1 to 2 cycles (up to 0.04 seconds for a 50Hz system). This is much faster than oil or air-insulated circuit breakers and reduces the arc’s exposure time, minimizing the risk of fire and damage. For instance, in a 10kV industrial power distribution system, a cable fault short circuit triggers the medium voltage VCB to cut off the current and extinguish the arc almost instantly, which prevents it from spreading to the adjacent switching gear.

GPSwitchgear’s medium voltage VCB utilizes premium vacuum chambers which have a vacuum degree of 10⁻⁶ Pa or higher, further improving safety with stable arc-extinguishing performance for more than 20 years.

Excellent Medium Voltage VCB Insulation Performance to Prevent Leakage Risks  

Insulation failure in medium voltage systems can lead to current leaks, equipment faults, and employee electric shocks. The medium voltage VCB relies on insulation due to two essential designs: first, the vacuum chamber construction: since it incorporates a vacuum chamber, it will function as an insulation chamber. The vacuum will prevent current leakage between the contacts at any rated voltage since it has much greater insulation strength than air or oil. The second feature the medium voltage VCB incorporates is epoxy resin or ceramic materials for the vacuum chamber casing, durable against moisture, dust, and chemical corrosion. Insulation failure due to moisture is, therefore, avoided. Medium voltage VCBs have no oil or gas to leak, making them safe for indoor and outdoor placements (unlike oil circuit breakers, which can leak and have oil insulation failure). For example, safe coastal regions in heavy industrial areas are perfect for VCBs since the moisture in the air and salt spray won’t clog the VCB’s insulation casing and vacuum chamber. The VCB can still function and prevent voltage insulation leakage faults. All purchased medium VCBs must have insulation AC withstand voltage and partial discharge tests to pass to comply with insulation and international safety standards.

Medium Voltage VCB Guarantees Equipment Protection through Accurate Current Interruption

Faults on medium voltage systems include short-circuit, overload, and earth fault currents, and can put transformers and other expensive equipment at risk. With expensive fault current transformers, medium voltage VCBs can accurately identify and interrupt fault currents because they are fitted with advanced integrated protection systems and can work with dynamic protective relays. These relays effectively analyze electrical systems in real-time and communicate with the medium voltage VCB when they detect a fault, and the VCB instantly activates the fault current interrupting mechanism. However, VCBs will not interrupt current that exceeds the maximum withstand rating of medium voltage equipment. For example, medium voltage VCBs for 20kV power systems can interrupt fault currents down to 20kA and prevent excess current flowing through the transformers and cables.  This protects the system from insulation and mechanical damage during overload.  For instance, a faulty overload condition from simultaneous operation of systems in 20kV commercial complex power system will trigger protection relays to maintain overload protection on the main transformer.

GPSwitchgear offers medium voltage VCBs that utilize either an electromagnetic mechanism or a spring-operated mechanism to ensure rapid contact separation, guaranteeing that interruption of the fault current occurs within the allotted safe time.

Medium Voltage VCB Maintenance Risks are Safe as Low Maintenance Required

Medium Voltage VCB cause less workload as they have low maintenance requirements. Other breakers like oil circuit breakers require repeated maintenance activities like oil changes, contact cleaning, gas pressure adjustments, and many more. These activities increase operational costs and put maintenance workers at risk of possible electrical exposure. VCB works on the principle of saving parts. Its vacuum chamber, and contact parts have long operational cycles—10,000 plus—before needing che initial routine maintenance. Maintenance of the operational mechanisms and lubercation of auxilary means (control circuits) can be performed without having to dismantle the high voltage cave, thus eliminating high voltage risk maintenance activities. This allows personnel to have lower exposure to high voltage and elimination of work like maintenance at burn contact. Such maintenance cycles are provided to maintenance performed to medium voltage VCB positioned at remote locations. Compared to quarterly maintenance of oil circuit breakers, medium voltage VCB positioned at remote locations, have maintenance cycles of 3 to 5 years. This substantially reduces work on-breaker maintenance. Such risks are maintained to GPSwitchgear’s medium voltage VCB modular. This design allows maintenance onauxillaries to be performed without impact to the vacuum chamber. This reduces the risk of poor maintenance and worker exposure.

Medium Voltage VCB Supports Interlocking Functions to Avoid Operational Mistakes  

Medium voltage systems have a high potential for dangerous and fatal incidents due to misoperation, for example, closing the breaker on a faulty line, or incorrectly opening the breaker during unauthorized normal load. VCB has built-in interlocking mechanisms to reduce the potential for misoperation. To start with, the VCB has a mechanical interlocking with the disconnector. The VCB can only be closed once the disconnector is in position, preventing closure on an open circuit. The VCB also has an electrical interlocking with the control system. The VCB can only be operated by authorized personnel with the correct access code or a control key, preventing unauthorized opening and closing. The VCB also has a status interlocking system. If the VCB vacuum chamber is leaking, the pressure sensors will detect arc failure and interlock the breaker, preventing it from operating during current interruption. A practical example will be in a middle voltage switchgear room where, if an operator tries to close the faulty line switch to the VCB, the mechanical interlock will prevent device damage by stopping the operator from closing the switch.

The medium voltage VCB from GPSwitchgear captures all operation logs, enabling management to track and assess functions, lowering the risk of intentional or unintentional operation errors.