SEL introduces the new SF6 free 3 position Switch Disconnector
Designed by our own R&D centre, thanks to a know-how and experience of over thirty years in the design and production of medium voltage equipment
General Description
In response to the latest requests from the European Community and as part of its ongoing innovation to provide effective solutions for environmental preservation, reduce gas emissions, and support the decarbonization process, SEL has developed a new three-position switch disconnector that is SF6-free, utilizing its own expertise and know-how.
New ECO-Friendly device
It is a new eco-friendly device that uses clean air as an insulating medium, free of SF6 gas. It has been designed to extinguish electric arcs using a vacuum interrupter. Through coordination with the movement of the three-position switch, it provides a solution for breaking/ opening, closing and earthing electric circuits in medium voltage networks. This new solution reduces greenhouse gas emissions and does not produce any toxic decomposition products during its operating process.
Patented System
A patented system leads all operations, coordinating the vacuum interrupter and switch disconnector.
Applications
The new device will be used to replace the existing SF6 Three position switch disconncetor device in the SEL switchgears TPS and TPR6 series.
Opening
(Fig. N.01) The current flows through the main contact (red-colored part) while the vacuum chamber contacts remain closed but do not carry any current. When the main contact moves (red part), it briefly connects with the vacuum chamber contacts (blue part) without interrupting the current flow. During this transition, the current flows through both the main circuit and the vacuum chamber. (Fig. N.02)
The main circuit is then disconnected, and all current flows through the vacuum chamber contacts (Fig. N.03). The patented mechanical system initiates the opening of the vacuum chamber contacts, and the circuit reaches the open state (Fig. N.04). Once the open position is achieved, the vacuum interrupter contacts remain in the open position (Fig. N.05).
Earthing
At this stage, it is possible to earth the switch and the linked circuit by operating the mechanism (see Fig. N.06).
Closing
By operating the mechanism, the switch moves from the earthing to the open position, allowing the following closing operation.
During the closing operation, the vacuum interrupter does not play any role and returns to a closed-contact status without being involved in current transmission or circuit closure. At this point, the current flows through the main contacts, and the circuit is fully energized. The vacuum interrupter contacts are fully closed and ready for opening operations. (Fig. N.07)
