Gasket design for SF6 leakage
Edwiin
02/06/2025
Leakage Causes and Gasket Design Considerations
Leaks in equipment often occur due to the deterioration of gasket materials over time and with use. Three critical factors influence gasket design and performance:
- Hardening of Gaskets:
High ambient temperatures and the heat generated by electrical currents passing through circuit breakers during normal operation can reduce the elasticity of gaskets, causing them to harden over time. - Chemical Attack:
In substations, SF6 gas undergoes chemical changes due to arcing during current interruptions. These short-circuit events decompose the pure SF6 gas, altering its composition and potentially damaging the gaskets. - Corrosion:
The filler materials used in equipment seals can be attacked by external environmental factors, leading to corrosion and eventual failure.
Sealing System Improvements
To address these issues, sealing systems have been enhanced:
- Previous Design:
Two O-ring seals were placed close together, with a leak-checking system between them. Grease was applied to protect against airborne pollutants. - Current Design:
A new sealing system incorporates three seals in a specially shaped configuration. The main seal is shielded from both internal and external corrosion by two auxiliary seals. The seal is housed in a groove designed to prevent scratching during equipment assembly. Additionally, the main seal now features a larger surface area to minimize the risk of leakage, even if the metal becomes caught during seal assembly.
This improved design significantly enhances the reliability and longevity of the sealing system, reducing the risk of leaks and equipment failure.
Online condition monitoring device (OLM2) on high voltage Circuit Breakers
This device is capable of monitoring and detecting various parameters according to the specifications outlined:SF6 Gas Monitoring:Utilizes a specialized sensor for measuring SF6 gas density.Capabilities include measuring gas temperature, monitoring SF6 leak rates, and calculating the optimal date for refilling.Mechanical Operation Analysis:Measures operational times for closing and opening cycles.Evaluates primary contacts separation speed, damping, and contact overtravel.Identifies signs of mec
Edwiin
02/13/2025
Anti pumping function in circuit breakers operating mechanism
The anti - pumping function stands as a crucial characteristic of control circuits. In the absence of this anti - pumping function, assume that a user connects a maintained contact within the closing circuit. When the circuit breaker is closed onto a fault current, the protective relays will promptly trigger a tripping action. However, the maintained contact in the closing circuit will attempt to close the breaker (once again) onto the fault. This repetitive and dangerous process is referred to
Edwiin
02/12/2025
Ageing phenomena of current pass blades in high voltage disconnector switch
This failure mode has three primary origins:Electrical Causes: The switching of currents, such as loop currents, can lead to localized wear. At higher currents, an electric arc may burn at a specific spot, increasing the local resistance. As more switching operations occur, the contact surface wears down further, causing an increase in resistance.Mechanical Causes: Vibrations, often due to wind, are the main contributors to mechanical aging. These vibrations cause abrasion over time, leading to
Edwiin
02/11/2025
Initial Transient Recovery Voltage (ITRV) for high voltage circuit breakers
Transient Recovery Voltage (TRV) stress similar to that encountered during a short-line fault can also occur due to the busbar connections on the supply side of a circuit breaker. This specific TRV stress is known as Initial Transient Recovery Voltage (ITRV). Given the relatively short distances involved, the time to reach the first peak of ITRV is typically less than 1 microsecond. The surge impedance of the busbars within a substation is generally lower compared to that of overhead lines.The f
Edwiin
02/08/2025
