SF6 RMU

Panel Structure

The SF6 panels have five system elements:

 

1. Electrical switching compartment including busbar compartment:

This is a gas-tight welded tank made of the stainless steel, which houses all the live parts including the bus bars. The incoming and outgoing power feeders, as well as the connections from the fuse compartments are led through cast-resin bushings that are individually tested for adherence to the maximum admissible partial discharge values.

 

2. Drives:

The sturdy drives - operated by spring or stored energy mechanisms - of the load-break and earthing switches and SF6 circuit breakers are located above the HV compartment. The spring operated drives are maintenance free. All parts of the Drive mechanism susceptible to corrosion are galvanically zinc coated. A motor operated system can optionally be retrofitted to all drive types; complying with all standard direct and alternating voltages.

 

3. Fuse Arrangement:

The fuse arrangement is designed as a plug-in system. All the fuse components are coupled to the contacts via cast-resin bushings from outside the gas tank. In the GA & the GAE systems, the fuse arrangement is plug-fitted. The plug-in parts - made from silicon rubber - are designed to be track-root-proof and arc-root-proof. The fuse arrangement is accessible only with the earthing switches switched ON.

 

4. Cable connection compartments:

These are generally provided, and are always in pressure-proof design. Arc-fault resistant compartments can also be supplied if required. They are separated from one panel to the next by sheet steel intermediate walls. Inspections or work can be carried out in this way although the cable connection zone of the neighboring panel is live. As a standard, the front covers are interlocked against the corresponding earthing. The front cover can be opened only with the earthing switch switched ON. An anti-reverse interlock system can also be provided, if required. This prevents the corresponding load-break switch from being switched onto a live busbar when the termination zone is open (front cover removed). The mechanism can be operated only with the front cover is in place, and the latch is closed. The earthing switch at the cable outgoer is not incorporated in this interlock and is switchable even when the terminal zone is open, which is necessary for cable testing.

 

5. Panel plinth