GB441998A - Improvements in and relating to electric switchgear structures - Google Patents

Abstract

441,998. Switchgear structures. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London. Oct. 18, 1935, No. 28846. Convention date, Oct. 20, 1934. [Class 38 (v)] A phase-unit for H.T. metal-clad switchgear comprises a circuit-breaker having a casing, with its terminals at the upper and lower ends of the casing respectively, means housing a disconnect device at each end of the casing and in vertical alignment therewith, means forming a terminal and junction chamber at the upper and lower extremities of the unit, a bus-bar positioned at the upper part of the unit and connected thereto through the adjacent junction chamber, and a feeder connected to the unit through the lower junction chamber. Figs. 1, 5 show the lay-out of three separate phase units A, B, C with respect to the bus-bars A<1>, B<1>, C<1> and feeders A<2>, B<2>, C<2>, with similar units T when transfer bus-bars are used. Each unit comprises an oil-filled housing 40 containing the movable and fixed contacts 2, 3 of an oil-blast, main breaker, which contacts are carried on insulators 10. Disconnect switches located in bushings 6, 7 control the connection of the breaker terminals to the feeder and bus-bar, the bushings being located in grounded. metal casings 8, the lower of which is mounted on junction chamber 41 communicating at 5 with the cable vault 60. Each disconnect switch is of similar kind and is shown in Fig. 2. The upper casing 8 supports an insulating sleeve 9 and, by means of cylindrical part 11, the insulator 10, and supports a plate 12 which forms a casing 13. Insulator 10 carries a contact 15 in sliding engagement at 16 with contact 2. Contact 15 supports a fixed conducting sleeve 17 which serves to guide 2 and also is in telescopic engagement with a conducting sleeve 19. The latter is carried by the movable disconnect contact 18 which co-operates with a fixed contact 14, connected to the bus-bars A<1>, C<1> by conductor 63 and to bus-bar B<1> by conductor 66, according to the phase. Insulating sleeves 21, 22 interleave with one another when 18 is lowered to isolating position. For the latter purpose, 18 is secured to a rack 24 driven by a motor 26 through pinions 25, shafts 27 and gearing 28, 29, this movement also serving to operate shutters 30 for the isolating contacts. The shutters are pivoted to plate 12 at 31 and controlled by dead-centre springs 32. They are provided with lugs 38, 39 engageable by lugs 35 which are rotated by shafts 27 and advanced by a bar 33 moved by the shafts 27. The actuating means for the contacts 2 is housed in a part 42 of the casing 8 and is interlocked with the motors 26. The overhead bus-bar B<1> is located in an extension casing 62 over the open end of junction casing 52 of phase unit B. Insulating sleeves 69, 70 co-operate with a slidable sleeve 71 to insulate the conductor joint and gas vents 73 are provided in the cover 72. Insulating sleeves 41<1>, 421, 51, 65 are also provided, and the vault 60 may contain current transformers and potential devices. A vent 55 closed by a ball-valve 56 is provided for the upper disconnect switch.