Engineering Bulletin No RW25 Rotary Wafer Switches - Model MU-MA General Information These versatile miniature switches have 25.4 mm diameter moulded wafers and are available in 2 versions, 36 indexing - having 18 clip positions and 30 indexing - having 22 such positions. 15, 45 and 60 indexing are variations of the latter.Optional features include concentric shafts, panel and spindle seals, printed circuit terminations and momentary contact models. Characteristics. Electrical, Maximum working voltage, 300Vdc/ac (rms). Contact rating, Current carrying 2amp continuous. Current breaking with a resistive/non-reactive load. 150mA at 250Vac (rms).. Proof Voltage. 1000Vrms at sea level. Insulation resistance. Not less than 500 megohms at 500Vdc. (between any 2 parts requiring electrical insulation) Contact resistance (initial). 10 milliohms maximum at 100mV (rms). 100mA.max. Mechanical. End stop strength. 0,8 0,1 Nm (114oz.in.) Temperature range. -40C. to +100C. Maximum Switching No. of Poles. 36 MU-MA (b) 30 MU-MA (a) 45 MU-MA (c) 60 MU-MA (d) 15 MU-MG Per Wafer 10 Positions. 12 Positions. 2 wafers 1 Pole. 2 to 10 ways 2 to 12 ways 2 to 8 ways 2 to 6 ways providing 1 pole 2 Pole. 2 to 5 ways 2 to 7 ways (fixed stop at 2 to 6 ways 24 way 3 Pole. 2 to 4 ways 2 to 5 ways positions 3, 5, 2 or 3 ways switching. 4 Pole. 2 or 3 ways 2 to 4 ways and 7 ways) 2 or 3 ways 5 Pole. - 2 to 3 ways 2 ways only 6 Pole. - 2 ways only on-off 7 Pole. - 2 ways only - Index Mechanism. The Type MU mechanism provides indexing angles of 30, 36, 45 and 60, (see Bulletin RW36 for full technical details). The low friction moulded cam followers in the assembly ensures a smooth indexing action. Balance pressure springs provide consistent and readily reproducible total switch torque values within the following ranges. 2 2 Light 7 to 18 x 10- Nm(10 to 26 oz, ins,) Medium 14 to 32 x 10- Nm (20 to 46 oz, ins,) 2 High 28 to 56 x 10- Nm (40 to 80 oz, ins,) Type A indexing mechanism may also be used as an alternative where a simpler, space saving mechanism is required. The switch then becomes model A-MA. 30 indexing only. Contacts & Standard. Silver plated brass. Terminations. Alternatives. - Hard gold plated or silver contacts are available at extra cost as are contacts with gold flash. Terminations. - Forward, standard: Straight, alternative. Rotor Blades. Standard. - Shorting. (make before break. MBB.) Alternative. - Non-shorting. (break before make. BBM.) Insulation. Stator. - Moulded glass fibre loaded diallylphthalate (DAP) Rotor. - Polycarbonate. Finish. Index Springs, Stainless steel: other metal parts, passivated zinc plated. Finishes to order. Mounting Details. Imperial (standard). Metric (alternative) Bush 3/8 x 32TPI (Whit.) M10 x 0.75. Shaft 0.25 dia. 6mm, dia. Nut 0.525 A/F. 14mm A/F. NSF Controls Limited Keighley West Yorkshire BD21 5EF (+44(0) 1535 661144 Fax: +44(0) 1535 661474 Email:RW25 MU-MA Variations. 1. Biased indexing is available giving momentary contact on positions 8 to 7, 5 to 4, 4 to 3, 3 to 2 and 2 to 1 as well as 3 position biased to centre. 2. Concentric shafts - dual concentric shafts and mechanisms for dual switching applications. (Not available for 36 indexing). 3. Insulated shafts. 4. Electrostatic shields. 5. Printed circuit terminations - 2 types are available giving a variation in mounting height of the wafer above the P.C.board. 6. Adjustable stops - 2 types are available. Front - can be set without dismantling the switch and are available on models MU-MA (a),(d) and A-MA with imperial bush. Rear - for use with all other indexing variations both Imperial and Metric versions. Dimensions Are In Millimetres Key To Details A. Shaft length: optional 0.40 (0.016) H. Bushing shoulder standard 3,2 (0.125) B. Bushing thread length: preferred standard 9.5 (0.375) 6.35 J. Front spacer, minimum dimension: MU-MA 9,5 (0.375), (0.250) available as an alternative. Special lengths A-MA 5 if necessary C. Flat length: length to specification. Tolerance 0.40 K. Other spacers: minimum dimensions. (0.016). Special shaft terminations may be provided Clips facing same direction NIL. to special requirements. Clips facing away or flat clips NIL. Clips facing each other 3 D. Angle of flat: to specification 2 specify position of flat, L. If no spacer 2,4 . Any length spacer desired may with switch shaft in fully anti-clockwise position when be inserted at this point. viewed from front or knob end. E. Flat thickness: standard 5.55 0.15 for grub screws M Thread extension: typically 3 x M2 x 0,4 any length 4.95 0.05 for push-on knobs desired. F. Distance of locating lug from shaft, centre line to centre line. P. Standard locating lug lengths: unsealed, projects 1.6 beyond mounting face sealed, 0,05 / 0,15 below mounting face G. Angle of locating lug: type MU mechanism 45,135,225 and 315 from horizontal centre line the alternative A type mechanism also includes 0 and 180 as viewed. NSF Controls Limited Keighley West Yorkshire BD21 5EF (+44(0) 1535 661144 Fax: +44(0) 1535 661474 Email: