Fergus Kyle wrote:
> Frans,
> You said:
> "You can connect this [12V point "C"] directly to the adjacent connector
> ('B' or 'R', which carries the actual output)............but a more correct
> way is to connect it directly to the battery......."
Consider B and R of the output of the regulator, and C as the sensor
wire, which measures the output voltage. You can connect them together
of course, and it will more or less work as intended. However, there is
always a small voltage loss over the cable from the regulator to the
battery. This means that the battery will get slightly less than
intended. So, by hooking the sensor wire (C) directly to the battery,
the regulator will automatically compensate for cable losses, because it
tries to keep the voltage at C constant. (That's why we call it a
regulator). Some my wonder if the cable attached to C won't have losses
by itself and defeat the purpose. The answer is No, because there is no
current in the cable attached to C. Put Ohm's law into the equation, and
you will see that without current, there won't be any cable loss. The
output of the regulator however will provide all the power to the ship,
so cable losses are at that point quite high. So, by connecting the
sensor wire at the battery, the regulator will keep the voltage at the
battery constant, regardless of cable losses.
> At the bottom of page78 of the Install 914F manual/1996 05 10,
> titled "Requirements for flawless operation of the rectifier-regulator". The
> fifth item states "never sever connection between terminal C and +B of
> regulator e.g. by removal of a fuse".
What they mean is that you should keep the sensor (C wire) always
somehow connected to the output of the regulator. But not necessarily
via the shortest route. It is logical if you think about it, if you were
to disconnect the sensor wire completely, the regulator would measure a
very low voltage (zero) and crank up the voltage at B and R untill it
measures the correct voltage, which will never happen in that situation.
If the manufacturer intended to keep C and B and R always connected via
the shortest route, he would have done this internally and not bothered
to make them available via separate pins.
Frans
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