Application and Ratings
The Chance Type D6 is a distribution-level, gang-operated, side-break switch for 15 through 38kV applications. D6 switches meet a continuous-current rating of 600 amperes, a momentary rating of 40,000 amperes, a three-second short- time current rating of 25,000 amperes, and all applicable NEMA and ANSI standards. It is available in 15 kV (110 kV LIW*), 27 kV (150 kV LIW*) and 38 kV (200 kV LIW*). The unit is a 600-ampere loadbreak switch with Duogap® expul- sion interrupters. Each switch comes prefitted with a socket to accept the Duogap. Orders also may specify switches come without the interrupters. With the Duogap, D6 is capable of switching load currents up to 600 amperes, with full recov- ery voltage across the switch, and interrupting transformer magnetizing and line-charging currents. The D6 switch may be used for disconnecting, line sectionalizing, circuit breaker bypassing, and isolating.
Design Features
D6 jaw socket and hinge terminal pads are bronze castings with stainless steel supports. The blade is round tubular cop- per with flattened ends to allow for a silver/copper contact. Silver contacts are used to ensure smooth, easy operation.
Bases and Bearings
The switch base for 38 kV (200 kV LIW*) is galvanized-steel hat-section. A sealed, greaseless main bearing supports the rotating insulator. The stainless-steel balls are encased in a high-strength, heat-treated aluminum housing for mainte- nance-free operation. The switch base for 15 kV (110 kV LIW*) and 27 kV (150 kV LIW*) is extruded aluminum channel and the bearings are high-density Delrin.
Insulators
The Sky-Glaze®insulator is gray porcelain NEMA 3-inch BC.
Blade Opening
All side-break D6 switches open in the counter-clockwise direction.
Terminal Pads, Arcing Horn
NEMA-standard, two-hole terminal pads accept aluminum or bronze connectors. Tin-plated bronze D6 pads reduce resistance to assure efficient current transfer. A stainless steel arcing horn picks up load current, preventing burning or arc pitting on the main contacts.
Interrupters
Chance Duogap® expulsion interrupter makes the D6 a loadbreak switch. Built-in sockets on each switch accept the interrupter. The Duogap may be ordered with the switch or may be hotstick-installed for load management conversion. For more on the Duogap, see Bulletin No.14-9405.
