In order to detect mains Brownouts (a drop in mains voltage which can result in a "blink in the lights"), ISA has built and operates a system to continuously measure the three 230 V voltages of the IFA mains power. By measuring the three voltages with a high sample rate, the system can calculate the RMS voltage of each 50 Hz cycle. If any of the RMS voltages goes below a predefined alarm level (90.00%) a Brownout Event is recorded.

For each Brownout Event the following information is recorded for each of the three phases (L1, L2, and L3):

• Duration: The time (in seconds) where the RMS value for individual 50 Hz cycles is below the alarm level.
• Minimum RMS value: The minimum (one-cycle) RMS value measured during the event.
• Brownout value: The integrated RMS value missing relative to nominal. Calculated as the sum of nominal RMS value minus the actual RMS value (divided by the nominal RMS value) during the event (i.e. while the RMS values are below the alarm level). A value of 1 correspond to one full RMS period missing (but typical a Brownout event will spread over several 50 Hz periods). Values below ~0.5 will generally not give problems for most equipment. A value above 1-2 will often cause problems.

Also, for each Brownout event two plots are generated. One plot shows the RMS values of the three phases around the event, and the other plots directly shows the three measured mains (sinusoidal) curves around the Brownout event. The Brownout Detector plots are exported and shown on the IFA Brownout Detector web page.

ISA also operates an SMS service, where SMS's are sent when a Brownout Event has happened with a Brownout value larger than 0.500. To sign up to receive an alert via SMS, go to this page (local AU access only).

Furthermore, the system generates plots with (RMS) voltages for the last 1 hour and the last 48 hours, which can be found on the IFA Mains Monitor web page.

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In depth description

The system consists of a small print where the voltages of three phases via a resistor network are brought into the range ±10 V. The voltages are then digitally sampled with a sample rate of ~3 kS/s by a National Instruments USB-6000 DAQ device. A fourth channel gives the possibility of measuring the voltage of a separate additional single phase. This separate channel is using a transformer to bring the voltage into the range of ±10 V. This is done to have the possibility of a separate neutral for the fourth channel. In real time a LabVIEW program then analyzes the input streams, and for each input calculates the RMS value for each 50 Hz period. In addition to the RMS values, minimum and maximum voltages, as well as the duration of each individual 50 Hz period are found. The individual period durations can easily be converted into corresponding frequencies. This then gives a measurement of the true 50 Hz frequency for each 50 Hz cycle. The LabVIEW program is averaging all these individual values and providing averaged values every 1.0 s and every 60 s. The averaged values are published to ConSys, where they can be plotted and saved regularly. In addition to providing the continuous data stream of RMS, min, and max values, the program is also always monitoring the individual RMS values. If an RMS value is below a preset alarm level, the program integrates the RMS values while they are below the alarm level. The integration directly gives the duration of the sub-nominal RMS values, and finding the minimum RMS values are also straightforward. For each of these Brownout Events a Brownout Value, which is a measure of the severity of the brownout, is also calculated.     Brownout Value = Sum ((nominalRMS - measuredRMS) / nominalRMS),             where the sum is over all the 50 Hz cycles with sub-nominal RMS values. The Brownout Value goes from 0.1 to "infinite". A value below ~0.5 will usually not give problems for most equipment, whereas values above 1-2 generally will cause problems for some equipment (in our experience a brownout value above 1-2 will most often cause failure of some supplies at the ASTRID2 facility). When the Brownout Event is over, the program generates plots with RMS values and the direct voltages during the Brownout Event, and triggers sending out alarm SMS's. If the Brownout duration is longer than 2.0 s, the event is categorized as a power cut. An SMS will then be generated reporting "Mains Power Cut". For each of the 3 phases, a FFT is done regurlarly (configurably to be every 0.1-10 s).

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Links:
        IFA Brownout Detector:     Shows data and plots from the last Brownout Event.
        IFA Mains Monitor:           Shows plots of the RMS voltages for the last 1 h and 48 h.
        IFA Mains Monitor FFT:    Shows plots of FFT of voltages for the last 1 h.

Systems for measuring the mains voltages at the ASTRID ring and at the AMS facility is on the way.

To sign up for a SMS alert from the IFA monitor, see here (local AU access only).

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ConSys Parameters:
MainsMonCmmn, MainsMonL1Cmmn, MainsMonL2Cmmn, MainsMonL3Cmmn
MainsMonAst, MainsMonL1Ast, MainsMonL2Ast, MainsMonL3Ast
To come: MainsMonAms, MainsMonL1Ams, MainsMonL2Ams, MainsMonL3Ams

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Last Modified 09 July 2024