Created Power monitoring calibration (markdown)

Power-monitoring-calibration.md

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+You might need to calibrate your power metering device as correct measurements are influenced by hardware and timing differences.
+
+This is how to do it:
+
+You will need a:
+- calibrated multimeter (AC capable)
+- incandescent light bulb (we use a 60W one in the example)
+- (optional) power meter (aka Kill A Watt)
+
+1. Connect the light bulb to your device. (Optional: plug your device into the power meter)
+2. Open the Web UI for your device in one window and another window to that same devices Console
+3. Turn power on and wait a few seconds for the power metering to settle on a stable power reading
+4. Verify the **Power** reading in the web UI (optinal: and with the power meter) for the expected 60W and if needed change the power offset with command: <BR>&nbsp;&nbsp;&nbsp;&nbsp;`PowerSet 60.0`<BR>&nbsp;&nbsp;&nbsp;&nbsp;*(if you're using something with different power draw enter the appropriate number)*
+5. Verify the **Voltage** reading with the multimeter and if needed change the voltage offset in V with command: <BR>&nbsp;&nbsp;&nbsp;&nbsp;`VoltageSet 235.5`<BR>&nbsp;&nbsp;&nbsp;&nbsp;*(235.5 would be replaced with your measurement which varies depending on the electrical standards and your electrical grid)*
+6. Verify the **Current** reading by calculating current value (amperage) using formula **P<sub>(W)</sub>/I<sub>(V)</sub>=I<sub>(A)</sub>** and if needed change the current offset in *mA* (mA=A\*1000) with command:<BR>&nbsp;&nbsp;&nbsp;&nbsp;`CurrentSet 254.777`<BR>&nbsp;&nbsp;&nbsp;&nbsp;*(instead of 254.777 enter your calculation value of ***A multiplied by 1000***)*
+
+Current calculation:   
+```
+P/U=I
+W(atts)/(V)oltage=(A)mperes
+
+watts/volts *1000=CurrentSet value
+(60.0/235.5)*1000=254.777
+```