9/17/2012 1:38 PM | |
Joined: 9/27/2006 Last visit: 2/13/2025 Posts: 12336 Rating:
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Hello kelese; Wikiedia is generally a reliabe source of basic techniocal information for these types of questions: http://en.wikipedia.org/wiki/Inrush_current "Inrush current, input surge current or switch-on surge refers to the maximum, instantaneous input current drawn by an electrical device when first turned on. For example, incandescent light bulbs have high inrush currents until their filaments warm up and their resistance increases. Alternating current electric motors and transformers may draw several times their normal full-load current when first energized, for a few cycles of the input waveform When an electric motor is first energised, the rotor is not moving, and a current equivalent to the stalled current will flow, reducing as the motor picks up speed and develops a back EMF to oppose the supply. AC induction motors behave as transformers with a shorted secondary, until the rotor begins to move, while brushed motors present essentially the winding resistance. The duration of the starting transient is less if the mechanical load on the motor is relieved until it has picked up speed. For high power motors, the winding configuration may be switched during start-up to reduce the current drawn." Hope this helps, |
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