
Jul 31, 2025
nstructions for installation, operation, and maintenance of the SL 15 kV, 300A vacuum contactor-SL72S4SH3LANL7MNR25
The SL contactor has its main contacts sealed inside ceramic tubes from which all air has been evacuated, i.e., the contacts are in vacuum. The arc simply stops when the current goes through zero as it alternates at line frequency. The arc usually does not survive beyond the first half cycle after the contacts begin to separate. The ceramic tube with the moving and stationary contacts enclosed is called a vacuum interrupter or a vacuum bottle and there is one such bottle for each pole of the contactor. A metal bellows (like a small, circular accordion) allows the moving contact to be closed and pulled open from the outside without letting air into the vacuum chamber of the bottle.