Eaton Power Xpert PXM 4000 User And Installation Manual

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Page 86 IM02601004E www.eaton.com6 Meter Settings Using the Web ServerSUB-CYCLE DISTURBANCEThe Power Xpert Meter captures sub-cycle disturbances with its regular metering hardware, whichsamples at 30.72 ksps. You can set the dv/dt Threshold and Absolute Threshold for Van, Vbn, Vcn,Vab, Vbc, and Vca. In addition, you can select the kind of action that will occur when one of thethresholds has been reached; Capture Waveform, Capture Parameters and/or Send E-mail.The Absolute Threshold Voltage setting is intended to trigger on Voltage spikes that exceed the nor-mal positive and negative peak values, which are typically 1.4 times the rms line-to-ground Voltage.It is important to set this threshold safely above the expected peaks. The Settings page suggestsa threshold that is 20% above the Nominal L-L Voltage (divided by the PT ratio). For example, a120V/208V system has a 120V rms and 170V peak (line-to-ground), and so a 250V threshold isappropriate (i.e. 208 + 20%).The dv/dt Threshold setting is entered in dv while the dt is fixed at the hardware sampling rate. TheSettings page suggests an aggressive threshold. Specifically, the settings page suggests a thresh-old that is 5% of the Nominal L-L Voltage (divided by the PT ratio).To calculate the volts per microsecond, multiply the threshold Volts by 0.03072. For example, if thedv/dt Threshold is set at 20V, the Volts per micro second would be 0.744 (i.e. 20V x 0.0372 Msps =0.744 V/ microsecond).A 30.72 ksps sampling rate and a pure 120V sine wave would result in a dv of 1.5V per sample atthe zero crossing. A disturbed waveform would have a much higher dv/dt.NOTE: To notify Power Xpert software of sub-cycle disturbances, select the Send Web ServicesNotification box.Locating Sub-cycle Disturbance Setup on the Web1. From the Settings main page, select the Triggers tab.2. Select the Sub-cycle Disturbance arrow.3. Underneath the Sub-cycle Disturbance arrow is a list displaying all of the current settings.4. Click Edit to change any of the listed settings.5. Click Save when new entries are completed. Click Close to exit Edit mode.