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STRAND DIMMERS "SUNSET" DIMMERS TYPES A AND A.1 (ELEMENT PATTERN)
These dimmers have been specially designed for use on "STRAND" switchboards, etc., in a compact form, dimensions being reduced to a bare minimum. They consist of a substantial frame with replaceable elements arranged in two halves, these being connected in series through a movable brush of anti-friction material.
Type A "Sunset " dimmer. The Type A dimmer is capable of handling a maximum load of 2,500 watts at 200/250v. or 2,000 watts at 100/110v. The Type A.1 dimmer will handle a maximum load of 3,500 watts at 200/250v. For loads up to a maximum of 3,500 watts at 100/11 Ov. the two halves of a Type A.1 dimmer are connected in parallel. This is effected by fitting collector segments and using a double brush. A wide range of variable loads can be handled on these dimmers, the maximum variation being plus or minus 33 !% of the rated load . The maximum carrying capacity of a dimmer is reduced to 80% of the figures stated above when wound for a variable load .
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For loads greater than those specified above a number of dimmers can be coupled for operation by a single control. Frame.-Die castings of robust design with interchangeable mountings; these can be suitably arranged for front or rear of switchboard entry, and for banking for motor drive. Panels.-Pierrite C.O. grade heat-resisting insulating material, of ample size to prevent warping. Terminals and Studs.-Brass studs of ample size are fitted with special collets for connecting elements. Elements.-Pierrite C.O. grade heat-resisting insulating material wound with graduated winding of nickelcopper alloy wire . Wire is non-corrosive and is unaffected by atmospheric conditions and also has a negligible temperature co-efficient. Brush.-Anti-friction "Copper Morganite " of ample section to carry current required without voltage drop. lnsulation.-Panels, elements, brush and other live parts are completely insulated from the frame with bushings and washers, care being taken to prevent damp creeping in at these points. The insulation resistance of an individual dimmer is not less than 20 megohms measured with a 500-volt testing set. General.-All dimmers have a definite "off" position. Dimmers are made with 100 steps of resistance and windings are calculated to give flickerless dimming from "full on " to "off" when used with the rated load.
LONDON, MANCHESTER, GLASGOW
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DARLINGTON , DUBLIN , MELBOURNE
