PQ measurements with ION 7650 in a 3W Delta System

[ekourany_btupan]

Hi Guys..

I have an application for power and quality monitoring in a Data Center.. However, the data center power system configuration is Delta 3W ungrounded.. The meter to be used is an ION 7650 with 3-Wire Delta, 2½-Element, Direct Connection (VOLTS MODE = Delta)

My concern is that sag & swell as well as transient detection functionality is based on the line to neutral voltage reference.. I am a bit puzzled as to what would be the correct voltage reference to provide on the NOM VOLTS configuration parameter that is required to input  in order to activate this detection functions within the meter.. and secondly, but most importantly how to interpret the meter sags and swell, and transient captured data.. i.e. power quality reports/ CBEMA curves in the context of an ungrounded system, etc..

I wonder if you can share some light and "heads up" into this particular application and perhaps share some tech-notes that explain in bit more detail how the meter sags & swell and transients frameworks work. This would be very valuable in the hopes to give the end user / customer a better understanding of his particular setup and what type of data/information to expect from implementing PQ analyzer within their facility with ION 7650 meters.

Thanks for your prompt comments and guidance.

[sesa56307_bridg]

I don't have a deep expertise in Delta 3W ungrounded systems (I'm others can provide more detailed insight there).  However, I do know that the Sag/Swell and Transient features on the ION7650 are designed to work properly with a line-to-line voltage reference in Delta mode.  The associated ION modules use a nominal voltage setting that is interpreted as a line-to-neutral value for Wye systems, or a line-to-line value for Delta systems.  So the nominal voltage value should be interpreted correctly in both cases.  And the resulting calculation outputs are definitely based on line-to-line values for Delta systems.

I suggest the ION Reference document as a good place to start for a full understanding of the Sag/Swell and Transient modules.  Here are a couple of excerpts.

Description of the "Nom Volts" setup register on the Sag/Swell module:

Description of the "Nominal" input on the Transient module (which is typically linked to the Sag/Swell Nom Volts setup register by default):

[ekourany_btupan]

Thanks David. That was very helpfull.

Indeed after reviewing the latest ION Reference manual it is clear that the ION7650 are designed to work properly with a line-to-line voltage reference in Delta mode, and that the NOM VOLT setup register should be fed with the line to neutral or line to line voltage values depending on power system configuration.

I guess the down fall for the delta configuration, from what I have found so far, is that Line to ground disturbances however, can´t be monitored with the meter when the power system is Delta ungrounded and the meter is wired and configured with as DELTA 3W system.