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Autotransformers

An autotransformer, also known as a step-down transformer, is an electrical transformer with only one winding. The winding has at least 3 taps where electrical connections are made. Autotransformers have the benefit of being small, light and cheap compared to dual-winding transformers.
Autotransformers are used to step up or step down voltages in the 110V-115V-120V range and 220V-230V-240V range. This allows electrical equipment from the US to be fed from higher European voltage.
Applications
• Can be used as a method of soft starting induction motors
• In UK railway applications
• In audio applications, tapped autotransformers are used to adapt speakers to constant-voltage distribution systems
• Power applications to interconnect systems operating at different voltages
• Special autotransformers are used on rural power distribution lines so that customers further away receive the same average voltage as ones nearer to the source

...
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Description Price Primary Voltage Rating Secondary Voltage Rating Power Rating Construction Mounting Type Core Type Termination Type Length Dimensions Width Depth Minimum Operating Frequency Maximum Operating Frequency Minimum Temperature
RS PRO 250VA Enclosed Autotransformer, 220 V ac, 230 V ac, 240 V ac Primary, 115V ac Secondary
RS Stock No. 504-199
BrandRS PRO
£67.92
Each
Units
 220 V ac, 230 V ac, 240 V ac 115V ac 250VA Enclosed Chassis Mount, Floor Standing, Wall Mount - - 81mm 81 x 136 x 100mm 136mm 100mm 50Hz 60Hz -
RS PRO 100VA Enclosed Autotransformer, 220 V ac, 230 V ac, 240 V ac Primary, 115V ac Secondary
RS Stock No. 504-183
BrandRS PRO
£60.37
Each
Units
 220 V ac, 230 V ac, 240 V ac 115V ac 100VA Enclosed Chassis Mount, Floor Standing, Wall Mount - - 65mm 65 x 115 x 78mm 115mm 78mm 50Hz 60Hz -
RS PRO 50VA Enclosed Autotransformer, 230V ac Primary, 115V ac Secondary
RS Stock No. 504-202
BrandRS PRO
£43.25
Each
Units
 230V ac 115V ac 50VA Enclosed Chassis Mount, Floor Standing, Wall Mount - - 58mm 58 x 63 x 70mm 63mm 70mm 50Hz 60Hz -
RS PRO 1kVA Enclosed Autotransformer, 220 V ac, 230 V ac, 240 V ac Primary, 115V ac Secondary
RS Stock No. 504-206
BrandRS PRO
£145.55
Each
Units
 220 V ac, 230 V ac, 240 V ac 115V ac 1kVA Enclosed Chassis Mount, Floor Standing, Wall Mount - - 115mm 115 x 192 x 137mm 192mm 137mm 50Hz 60Hz -
RS PRO 150VA Enclosed Autotransformer, 220 V ac, 230 V ac, 240 V ac Primary, 115V ac Secondary
RS Stock No. 504-189
BrandRS PRO
£57.69
Each
Units
 220 V ac, 230 V ac, 240 V ac 115V ac 150VA Enclosed Chassis Mount, Floor Standing, Wall Mount - - 73mm 73 x 120 x 89mm 120mm 89mm 50Hz 60Hz -
RS PRO 500VA Enclosed Autotransformer, 220 V ac, 230 V ac, 240 V ac Primary, 115V ac Secondary
RS Stock No. 504-195
BrandRS PRO
£94.66
Each
Units
 220 V ac, 230 V ac, 240 V ac 115V ac 500VA Enclosed Chassis Mount, Floor Standing, Wall Mount - - 98mm 98 x 145 x 118mm 145mm 118mm 50Hz 60Hz -
Block Enclosed Autotransformer, 115 V ac, 230 V ac Primary, 115 V ac, 220 V ac, 230 V ac, 240 V ac Secondary
RS Stock No. 293-2656
Mfr. Part No.AIM 1.6/0.8
BrandBlock
£41.77
Each
Units
 115 V ac, 230 V ac 115 V ac, 220 V ac, 230 V ac, 240 V ac - Enclosed Panel Mount - Screw 166mm 166 x 77 x 76mm 77mm 76mm 50Hz 60Hz -20°C
Block 200VA Autotransformer, 230V ac Primary, 115 V ac Secondary
RS Stock No. 310-1156
Mfr. Part No.SAT200
BrandBlock
£60.31
Each
Units
 230V ac 115 V ac 200VA - - - - 166mm 166 x 76 x 77mm 76mm 77mm - - -
Block 300VA Autotransformer, 230V ac Primary, 115 V ac Secondary
RS Stock No. 310-1162
Mfr. Part No.SAT300
BrandBlock
£81.07
Each
Units
 230V ac 115 V ac 300VA - - - - 223mm 223 x 97 x 117mm 97mm 117mm - - -
Block 100VA Autotransformer, 230V ac Primary, 115 V ac Secondary
RS Stock No. 310-1140
Mfr. Part No.SAT100
BrandBlock
£59.69
Each
Units
 230V ac 115 V ac 100VA - - - - 166mm 166 x 76 x 77mm 76mm 77mm - - -
Carroll & Meynell 30kVA Autotransformer, 380 V, 400 V, 415 V Primary, 380 V, 400 V, 415 V Secondary, Bobbin Core
RS Stock No. 436-8877
Mfr. Part No.CMA30K/FM0
BrandCarroll & Meynell
£572.71
Each
Units
 380 V, 400 V, 415 V 380 V, 400 V, 415 V 30kVA - - Bobbin - 420mm 420 x 350 x 260mm 350mm 260mm - - -
Carroll & Meynell 3kVA Autotransformer, 230V Primary, 114.1V ac Secondary, Bobbin Core
RS Stock No. 436-8883
Mfr. Part No.CM3000/A/US
BrandCarroll & Meynell
£164.26
Each
Units
 230V 114.1V ac 3kVA - - Bobbin - 205mm 205 x 195 x 260mm 260mm 190mm - - -
Block 500VA Autotransformer, 230V ac Primary, 115 V ac Secondary
RS Stock No. 328-8051
Mfr. Part No.SAT 500
BrandBlock
£85.06
Each
Units
 230V ac 115 V ac 500VA - - - - 223mm 223 x 97 x 117mm 97mm 117mm - - -
Block Enclosed Autotransformer, 115 V ac, 230 V ac Primary, 115 V ac, 220 V ac, 230 V ac Secondary
RS Stock No. 293-2678
Mfr. Part No.AIM 5.0/2.5
BrandBlock
£71.08
Each
Units
 115 V ac, 230 V ac 115 V ac, 220 V ac, 230 V ac - Enclosed Panel Mount - Screw 223mm 223 x 97 x 117mm 97mm 117mm 50Hz 60Hz -20°C
Block Enclosed Autotransformer, 115 V ac, 230 V ac Primary, 115 V ac, 220 V ac, 230 V ac, 240 V ac Secondary
RS Stock No. 436-9858
Mfr. Part No.AIM16/8
BrandBlock
£207.76
Each
Units
 115 V ac, 230 V ac 115 V ac, 220 V ac, 230 V ac, 240 V ac - Enclosed Panel Mount - Screw 284mm 283 x 200 x 165mm 165mm 200mm 50Hz 60Hz -20°C
Block Enclosed Autotransformer, 115 V ac, 230 V ac Primary, 115 V ac, 220 V ac, 230 V ac, 240 V ac Secondary
RS Stock No. 436-9842
Mfr. Part No.AIM10/5
BrandBlock
£165.62
Each
Units
 115 V ac, 230 V ac 115 V ac, 220 V ac, 230 V ac, 240 V ac - Enclosed Panel Mount - Screw 283mm 283 x 200 x 165mm 165mm 200mm 50Hz 60Hz -20°C
Carroll & Meynell 2kVA Autotransformer, 230V ac Primary, 115V ac Secondary, Bobbin Core
RS Stock No. 347-6668
Mfr. Part No.CM2000/A/US
BrandCarroll & Meynell
£135.72
Each
Units
 230V ac 115V ac 2kVA - - Bobbin - 205mm 205 x 195 x 260mm 260mm 190mm - - -
Carroll & Meynell 10kVA Enclosed Autotransformer, 380 V, 400 V, 415 V Primary, 380 V, 400 V, 415 V Secondary
RS Stock No. 436-8861
Mfr. Part No.CMA10K/FM0
BrandCarroll & Meynell
£400.02
Each
Units
 380 V, 400 V, 415 V 380 V, 400 V, 415 V 10kVA Enclosed Floor Standing - - 420mm 420 x 270 x 325mm 270mm 325mm 50Hz 60Hz -
Block Enclosed Autotransformer, 115 V ac, 230 V ac Primary, 115 V ac, 220 V ac, 230 V ac, 240 V ac Secondary
RS Stock No. 293-2662
Mfr. Part No.AIM 3.2/1.6
BrandBlock
£58.27
Each
Units
 115 V ac, 230 V ac 115 V ac, 220 V ac, 230 V ac, 240 V ac - Enclosed Panel Mount - Screw 223mm 223 x 97 x 117mm 97mm 117mm 50Hz 60Hz -20°C
Block 600VA Autotransformer, 230V ac Primary, 115 V ac Secondary
RS Stock No. 328-8067
Mfr. Part No.SAT 600
BrandBlock
£84.55
Each
Units
 230V ac 115 V ac 600VA - - - - 223mm 223 x 97 x 117mm 97mm 117mm - - -
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