The PQ-Box 100 (and 200) Power Quality Recorders are true RMS recording devices and therefore have the ability to measure and record the DC component of an AC+DC waveform.
The units can be used for ‘just’ DC voltage measurements (for example, where customers use the PQ-Box 100’s ‘0.1 % accuracy’ to very accurately set a 24 Vdc supply).
After logging data with the PQ-Box 100/200, WinPQ mobile software can be used to display over 360 different values, including ‘U eff’ (True RMS value of AC+DC component) and ‘DC Voltage’(the calculated DC component of the ‘U eff’ value). The ‘DC Voltage’ trace is derived from the calculated DC component of an AC +DC waveform and can be displayed in either volts units or as a percentage of the total RMS value.
Measuring DC offset with PQ-Box 100 & PQ-Box 200.
If you have an application when measuring DC components is of interest, we would be interested in setting up some field measurements. Perhaps you are interested in:
- Quantifying the DC effects of inverter and pulse width modulated loads on the AC supply
- Investigating corrosion risks due to resulting DC current on an LV system
A ‘DC Current’ value is also recorded by the PQ-Box 100, which is the current equivalent to that of voltage described above. ‘Hall-effect’ DC-measuring current clamps (200 mA to 60 A or 0.5 A to 600 A), or 2 A current shunts are available, which are suitable for measuring AC+DC. This means true RMS current and DC component measurements are possible. DC measurements are NOT possible when using the standard mini-clamps and Rogowski coils, as these are AC coupled.
For further information, please refer to the Power Quality section of our website Technical Library (PO Box 100 Hints and Tips #11).