Submetering Measurement Toccoa GA

Electric utilities are working harder than ever to stay competitive, manage capacity and protect revenue. To differentiate themselves from competitors, many utilities are offering power quality and other efficiency-related services. As a result, new power quality measurement tools are reflecting this same multi-purpose field service ethic.

Many three-phase analyzers that technicians already use to measure power factor and trend power quality now offer user-settable ratios for displaying readings as if measuring at the primary side of PTs and CTs. In addition, it is notable that they also verify revenue meters.

Enough revenue meters are out of tolerance that a 2001 Electric Power Research Institute study estimated meter-related losses at $5 million to $20 million per year for a medium-sized U.S. utility. Therefore, using a multi-purpose analyzer allows utility technicians to offer more customer services in less time and quickly audit revenue meters during each site visit.

Power quality analyzers

New handheld three-phase power quality analyzers are rated for use at the service entrance and will trend data easily, without setup. To support detailed yet efficient assessments of substations and customers' power, new analyzers will:

• Measure voltage, current, frequency, power, power factor, power consumption (energy), unbalance and flicker, harmonics and inter-harmonics on all three phases and neutral
• Log dips, swells, and interruptions
• Trend all measurements on-screen, with automatic scaling
• Check conformity to EN50160 limits or to custom limits
• Capture 40 waveforms showing detailed dips, swells, interruptions or transients
• Meet 600V CAT IV, 1000V CAT III safety standard required for measurements at the service entrance
• Transfer stored measurements to the PC.

The Monitor function on certain analyzers allows technicians to check overall power quality against standards—or verify custom-set limits—and show the customer a clear go/no-go screen.

Transformer connections

Some analyzers can be connected directly to low-voltage services, including 120V/240V, 480V, and 600V. They can also connect in parallels with primary metering using PT or CT loops and a set of precision 5A current clamps. Technicians can set custom scale factors to display readings in primary units. These analyzers will also support all standard power configurations, including:

• Single-phase 120/240V
• Three phase grounded wye
• Three phase delta
• Three phase high leg delta
• Three phase open leg delta 2A
• Single phase and 3 phase IT

Conversely, large consumers can install power factor correction or harmonics mitigation that affects the distribution system. Utilities can perform before-and-after readings to help customers evaluate solutions and to check for impact on distribution. Figure 2A shows current lagging voltage at the service entrance of a commercial building. Figure 2B shows the same service entrance after applying power factor correction. Applying the correction creates a 10 percent reduction in current consumption, but also results in somewhat higher current distortion.

With the Power and Energy display on the Fluke 430 Series, for instance, technicians connect the analyzer and then press the soft-key labeled "MANUAL COUNT +1" to increment the counter each time the marker passes on the revenue meter.

Revenue meter verification

The meter verification test is similar to a hand-switch verification and can find tolerance problems. On new analyzers, technicians can use a soft-key for the test, with no configuration or accessories needed. The verification can be used on any electromechanical meter or electronic meter with an indicator or rotating disk.

How manual measurement works:

1. Set the scale factors

   Set CT and PT scale factors on the analyzer, if necessary. Under the FUNCTION preferences for the Power and Energy Function, set the pulse constant on the analyzer to match the pulse constant on the revenue meter (Kh). Then, use the down arrow button to see the pulse constant. Connect the 430 in parallel with the revenue meter.

2. Setup the energy measurement

   Select the Power & Energy mode from the main menu and press the Hold/Run soft-key twice. Press the TIMED soft-key, then specify the number of pulses to count before holding the results on the display. Press START to return to the Power and Energy Screen. Press the ENERGY soft-key to open the Energy display. Make sure Pulse Counting is turned on.

3. Perform the verification

   Press the RESET ENERGY soft-key to reset the energy counter as the marker passes on the revenue meter. Press the MANUAL COUNT + 1 soft-key each time the marker passes.

4. Read the results

   After the number of rotations specified in step 2 are done, the display will hold. Read the meter error, in percentage, from the lower right part of the screen.

   It should be noted that some utilities make a practice of auditing large customer power meters once a month to safeguard revenue. To that end, new multi-purpose power quality analyzers make this kind of personalized field service far more efficient—as well as feasible. These power quality analyzers also provide more customer-friendly data, which ultimately create effective new suggestions for adding value to customer service efforts.

Wade Thompson, power quality specialist for Fluke has also worked for RPM and BMI. Wade specializes in troubleshooting power quality problems at data centers, large embedded systems, utilities and industrial facilities. Wade can be reached at wade.thompson@fluke.com, or at 812-212-0150.