Abstract: A medium-voltage substation includes at least two insulative material chambers each provided with at least one opening for the gas-tight passage of a set of three-phase busbars. Each chamber contains a three-position three-phase switch for connecting the busbars to first gas-tight electrical feed-throughs and for connecting the first feed-throughs to second gas-tight feed-throughs connected to ground. The first feed-throughs of at least one chamber are each electrically connected to a single-phase cable. The first feed-throughs of each chamber are electrically connected either to a fuse or to a pole of a circuit-breaker disposed in an insulative material compartment.

Abstract: A high tension or medium tension circuit breaker having abutting arcing contacts. The circuit breaker includes a gastight insulating case filled with a gas having good dielectric properties. The case contains a stationary arcing contact; a moving arcing contact driven by a drive rod actuated by a mechanism outside the case. A blast chamber is defined by a piston integral with the moving arcing contact, slidably received in a fixed cylinder terminating in a blast nozzle, the cylinder and a ring. The circuit breaker further includes a lost motion mechanism to enable the drive rod to move over a given length in the circuit breaker opening direction without driving the moving arcing contact away from the fixed arcing contact.

Abstract: A pneumatic puffer circuit breaker for high tension stations comprises a sealed chamber filled with a highly dielectric gas, a fixed main contact (18, 39) and at least one fixed arcing contact (9, 14, 16) disposed as co-axial cylinders and deliminiting a first volume (12). A fixed blast nozzle (24) delimits in conjunction with the fixed arcing contact an outlet passage (12A) for gas from said first volume (12). A tubular moving main contact (29) and a tubular moving arcing contact (15) are disposed coaxially with each other and with the fixed contacts, and a cylinder (10) is mounted to co-operate with the fixed main contact during circuit interruption to compress the gas in said first volume. Said cylinder has a spring (11) urging it towards a drive member (20, 31) mounted to move with said moving contacts.