Eaton Power Xpert PXM 4000, Руководство пользователя и инструкция по установке

Страница: 137 / 292

www.eaton.com
IM02601004E
Page 129
8 Setup on the Web Server Pages
Click the Done button at the bottom of the page when entries are completed.
FAST TRANSIENT (AVAILABLE ON PXM8000 SERIES)
The Power Xpert Meter captures transients with optional hardware that samples 4 channels accord-
ing to user settings. You can set the dv/dt Threshold and Absolute Threshold for Vag, Vbg, Vcg and
Vng. You can also select the Sampling Speed as well as the kind of action that will occur when one
of the thresholds 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
normal positive and negative peak values, which are typically 1.4 times the rms line-to-ground Volt-
age. It is important to set this threshold safely above the expected peaks. The Setup page suggests
a threshold that is 20% above the Nominal L-L Voltage (divided by the PT ratio). For example, a
120V/208V system has a 120V rms and 170V peak (line-to-ground), and so a 250V threshold is
appropriate (i.e., 208 + 20%).
The dv/dt Threshold setting is entered in dv while the dt is fixed at the hardware sampling rate. The
Setup page suggests a conservative threshold to avoid false triggering. Specifically, the setup page
suggests a threshold that is 50% above the Nominal L-L Voltage (divided by the PT ratio). A mod-
erately aggressive lower threshold would be the 50% of the Nominal L-L Voltage (divided by the PT
ratio). To calculate the volts per microsecond, multiply the threshold Volts by the sample time. For
example, if the dv/dt Threshold is set a 10V and the speed selection is 6 Msps, the Volts per micro
second would be 60 (i.e., 10V x 6 Msps = 60V/microsecond).
Locating Fast Transient Setup on the Web
From the Setup Main Page, select Triggers from the tree structure on the left side of the page. The
tree structure will expand to list Out of Limits, Demand Overload, ITIC, Fast Transient, and Tran-
sient. Click Fast Transient. The page will update to list all the current Fast Transient settings. Use
the Edit button at the top of the page to edit settings.
When Edit is selected, the page will display drop down boxes and check boxes for use in changing
current settings. Click the Done button at the top of the page when entries are completed.