Intermediate pull cord switch
- Thread starter TicklyT
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So is the fan DC? Swapping line and neutral on a AC supply will not reverse a motor.
A normal intermediate should not be used for reversing polarity of a supply as they are not certain to be break before make and may create a transient short circuit across the supply as they operate. When used to swop strappers in a two way circuit that transient short circuit does no harm as one strap is live and the other switched live.
Eric - I intended to use the switch to replace the exising switch that reverses one of the field windings on the cap run motor.
Good point about the possibility of one pole making before t'other breaking Bernard, Maybe time for a re-think.....
Good point about the possibility of one pole making before t'other breaking Bernard, Maybe time for a re-think.....
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All is not lost. If the motor has two identical windings, one directly across the supply and the other via the capacitor then a make before break intermediate can be used.
If the end of the winding that goes to the capacitor is switched away from the capacitor and onto to supply live and the matching end of the other winding is switched away from supply live and onto the capacitor then this should reverse direction. Whether the motor fan assembly runs efficiently in reverse is another matter.
If the end of the winding that goes to the capacitor is switched away from the capacitor and onto to supply live and the matching end of the other winding is switched away from supply live and onto the capacitor then this should reverse direction. Whether the motor fan assembly runs efficiently in reverse is another matter.
The motor actually has four field windings. Three are switched in or out by a sequential switch to give different speeds, and one winding, connected via the capacitor and a commutating switch, controls the direction of rotation.
The direction switch reverses the two ends of that winding, so a switch that allows one pole to make before t'other breaks will temporarily short out that winding, connecting L to N via the capacitor..... Maybe that explains the early demise of the original switch....
Still haven't found a pull cord intermediate switch anywhere yet though...
The direction switch reverses the two ends of that winding, so a switch that allows one pole to make before t'other breaks will temporarily short out that winding, connecting L to N via the capacitor..... Maybe that explains the early demise of the original switch....
Still haven't found a pull cord intermediate switch anywhere yet though...
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