The VS1-12 side-mounted vacuum circuit breaker features a fixed structure, primarily designed for installation in fixed switchgear cabinets. It can also be used independently for controlling and protecting transmission and distribution lines.
Principle of the Permanent Magnet Operating Mechanism:
When the circuit breaker is in either the closed or open position, no current flows through the coil. The permanent magnet, combined with a low magnetic impedance path provided by the moving and stationary iron cores, maintains the iron core in a stable position at the upper and lower limits, without the need for mechanical locks. When a control signal is received, current is applied to the closing or opening coil, generating a magnetic field. This magnetic field, combined with the permanent magnet's field in the moving and stationary iron cores, creates a synthetic magnetic field that drives the moving iron core and the attached drive rod. This action causes the switch mechanism to open or close within a specified time at a defined speed.
The reason this mechanism is referred to as a two-position bistable structure is that the moving iron core remains in either of the two stroke-end positions without consuming energy. Unlike traditional electromagnetic mechanisms, which use springs or mechanical locks to hold the moving iron core in place, this permanent magnet mechanism does not require continuous energy input to maintain either position.
The permanent magnet operating mechanism integrates the functions of the traditional circuit breaker mechanism by combining an electromagnet with a permanent magnet. The permanent magnet replaces the traditional tripping mechanism and holds the core in position, while the opening and closing coils supply the necessary energy for operation. This results in a significant reduction in the total number of components, which improves the overall reliability of the mechanism.
Due to the inherent characteristics of the permanent magnet mechanism, the circuit breaker’s reliability is enhanced. The opening and closing characteristics are determined primarily by the coil parameters, and can be controlled electronically or via a microcomputer system. This allows for intelligent control and self-checking capabilities. The control system can use electronic components, such as external DC contactors, to manage the operation.
Arc Extinguishing Chamber Principle:
The VS1-12/M vacuum circuit breaker (with permanent magnet operating mechanism) uses a vacuum interrupter that relies on a vacuum as both the insulating and arc-extinguishing medium. The interrupter is maintained at a high level of vacuum. When the moving and stationary contacts in the operating mechanism open, an arc is generated between the contacts. Due to the unique contact structure, a longitudinal magnetic field is created in the contact gap, which helps to diffuse the vacuum arc, making it more uniform and evenly distributed over the contact surfaces.
As the current naturally crosses zero, the residual ions, electrons, and metal vapors rapidly recombine or settle on the contact surfaces and shields within microseconds. This rapid recombination restores the dielectric strength of the arc-extinguishing chamber, extinguishing the arc and successfully interrupting the current. The use of a magnetic field to control the arc in a vacuum provides the circuit breaker with excellent and stable interrupting capacity, ensuring reliable operation even under high current conditions.