ok Stuart, one more
- you
visualize what's happening by saying the voltage is being reduced, but electrically what happens is the current delivered to the motor is reduced - in practice it's always current regulation, not voltage regulation, as the system is designed so the generator and regulator maintain a constant voltage
- if the system is good the truck supplies 6 or 12V always
- voltage is the
potential for work the battery contains
- current is what 'delivers' the work, electrons move from the battery to the motor, from the point of highest voltage to lowest [why the fuel sender is on the ground side]
- resistance is what has to be overcome to produce work - the complete motor
circuit has a resistance
- power is work done - heat in an electrical circuit
the
power available to the motor must be reduced, and the battery
potential can't be reduced, so the current in
the circuit must be reduced, which is done by adding resistance to the
circuit, which uses up some of the current generated power before it gets to the motor - the result may be quite the same as if you dropped the battery voltage a bit, but the real 'action' is the dissipation of some of the current as heat [power] in the switch - it's the current flow that really generates the work, not the voltage potential
plug some
figures in here , keeping in mind that the voltage
to the circuit can't vary, and see
this simple circuit provided by your very own govt - read the 'bottom line'
and Dennis - the difference in the switches is that the multiple 'coils' on the switch [which are still resistance units], are better able to dissipate the heat, and they were usually covered w/ a sleeve of insulation for that, and to lessen the chance of someone touching them, the basics are still the same
Bill
