EDM Controller Qustion

In searching the archives and other sources, I understand the basic controls of the EDM as follows:

1 - Measure voltage when electrode discharges
2 - If V < desired gap voltage, move electrode up (too close)
3 - If V = desired gap voltage, don't move electrode
4 - If V > desired gap voltage, move electrode down (too far away)
5 - Goto 1

This is just a simplification but is sufficient for my question.

When you build your own power supply, you have a capacitor at the output. This is what you measure (V). When you purchase your power supply, what do you measure? Can I assume that there is also a capacitor at the output of the power supply that I can measure the same way?

Also, for any usefull work to be accomplished, there must be power (P=V*I). If there is high voltage and no current then there is no power. If I'm using a shunt resistor to measure the voltage, and a voltage is measured, then there will be current (I=V / R). Likewise, if I try to measure current with the shunt resistor, and a current is measured, then there will be a voltage (V=I * R). Do I need to worry about this or does measuring one validate the other?

I would appreciate any help anyone has to offer on EDM'ing.

Regards,

James


[Non-text portions of this message have been removed]