Janitza MRG Flex and Unipower Unilyzer Analyzers

Short answer

The Janitza MRG Flex units are portable measurement cases that combine a network analyzer (UMG 512-PRO Class A or UMG 96-PQ-L-LP) with flexible Rogowski coils, and also record residual current. The Unipower Unilyzer 900 is a compact IP65 analyzer weighing 700 g, Class A according to IEC 61000-4-30, with built-in Wi-Fi. Both are used to investigate voltage quality and disturbances in a low- and medium-voltage network.

Two ways to measure in the field

A portable power quality analyzer is chosen for three things: the measurement class according to IEC 61000-4-30, the way the current is measured and how easy it is to install. These two families solve the problem in different ways.

Janitza MRG Flex

The Janitza MRG Flex units (Germany) are mobile measurement cases: a network analyzer installed in a rugged carrying case, with fused voltage probes and flexible Rogowski coils. According to the manufacturer, each case carries a UMG 96-PQ-L-LP or a UMG 512-PRO, depending on the variant, and can measure residual current and power quality (harmonics, short interruptions, unbalance) at all times.

MRG 512-PRO PQ Flex

Integrates the UMG 512-PRO Class A analyzer (IEC 61000-4-30).
Measures harmonic currents up to the 63rd order, flicker and short-duration interruptions.
Three-hour UPS backup, so as not to lose data if the supply at the measured point is lost.
Rogowski coils of 175 mm diameter, four in the set, with a range of 100 to 4,000 A.
Fused voltage probes, inputs for measuring residual current (the residual current transformer is not included) and PLC function.

MRG 96-PQ-L-LP Flex

About 3 kg, with a carrying backpack.
Harmonic currents up to the 65th order.
Rogowski with a range of 10 to 8,000 A.
Aimed at analyzing disturbances when there are network problems, at comparative measurements of energy meters and at recording residual currents.

Communication and software

Both offer remote access over Ethernet with an integrated web server. The GridVis-PQ program analyzes the data and generates standard quality reports, depending on the version: EN 50160, IEEE 519, ITIC and IEC 61000-2-4. A large internal memory (256 MB) allows long recordings, such as the one-week recording that EN 50160 requires. Janitza also offers the compact MRG 96RM-E RCM Flex, for energy audits, residual current recording and measurement of quality parameters.

Unipower Unilyzer 900

The Unilyzer 900 from the Swedish company Unipower is a compact power quality analyzer, intended for investigating customer complaints and network problems. According to the manufacturer:

It meets Class A of IEC 61000-4-30, with gapless measurements and algorithms according to that standard.
It weighs 700 g, has IP65 protection and fits in small electrical cabinets; it has no moving parts.
It includes built-in Wi-Fi and an Android app: the recording is read and downloaded from the vehicle, without climbing a pole or entering a hazardous area.
It measures power and energy in all three-phase configurations, wye and delta.
It stores about 170 days of measurements with the standard 32 MB memory, thanks to its own data compression method.
Typical parameters: voltage and current variations, dips and swells, flicker, harmonics, rapid voltage changes (RVC), unbalance, transients, ripple control signals and transformer monitoring.
PQ Secure evaluation software included, with classification of dips according to different standards.
Accessories: flexible Rogowski-type clamps for currents up to 5,000 A and magnetic core clamps, with automatic recognition of range and type.

The same line includes the Unilyzer 900c, of a similar form factor. For the specific data of that model and the class it corresponds to, consult the manufacturer’s data sheet.

Which standards apply

IEC 61000-4-30: measurement methods and Classes A and S.
EN 50160: voltage characteristics in public networks, with weekly assessment.
IEEE 519: harmonic distortion limits at the point of common coupling.
IEC 61000-2-4: compatibility levels in industrial installations.

Class A is the one that applies when the result can be arbitrated between two parties; Class S is enough for studies and diagnosis. Which class and which criterion are required in each case is determined by the contract or the applicable grid code.

How to read a recording

Verify the context: measurement point, connection, ratio of the clamps or transformers, period and plant operation during it.
Review the events (dips, interruptions, swells) and how they coincide with plant operations or network switching.
Examine the distortion: the harmonic current points to the source; the harmonic voltage reflects the effect at the point of connection.
Compare with the criterion: EN 50160, IEEE 519 or the contractual requirement.
Do not conclude from a short recording, except to diagnose a specific event.

The guide to the power quality analyzer and the one on power quality in industry explain which problems are investigated with these devices.

When each approach is suitable

A case with Rogowski coils is well suited to points with large-section cables or busbars and to recordings where, besides voltage quality, the residual current or the comparison with an existing energy meter is of interest. A compact analyzer such as the Unilyzer 900 is well suited to small cabinets, poles and hard-to-reach points, and to campaigns with many measurement points because it is installed quickly and downloaded over Wi-Fi. In both cases, what decides how useful the recording is, is the prior planning: what is to be demonstrated, at which point and for how long.

Precautions

Connection: phase order, polarity of the coils and transformation ratio correctly entered.
Position of the Rogowski coils: the measured conductor must be centered and the other conductors kept away.
Probe voltage: respect the measurement category of the panel and the protection fuses.
Time reference synchronized if several points are compared.
Safety: connection to energized panels with qualified personnel, PPE and procedure.

Power quality recording on request

Do you need this test? We perform it for you: depending on your case we recommend the right test and equipment and include it in the quotation. That way you get the test your case really needs, without paying for extra tests. We carry it out in Colombia, or elsewhere on request.

Learn about our testing and commissioning service and request your quotation through the form.

References

Janitza electronics GmbH, MRG Flex family pages and MRG 96RM-E RCM Flex manual (janitza.com).
Unipower AB, Unilyzer 900 page (unipower.se).
IEC 61000-4-30, Electromagnetic compatibility (EMC) – Part 4-30: Testing and measurement techniques – Power quality measurement methods.
EN 50160, Voltage characteristics of electricity supplied by public electricity networks.
IEEE Std 519, Recommended Practice and Requirements for Harmonic Control in Electric Power Systems.

Frequently asked questions

What advantage do Rogowski coils have in a portable analyzer?

They are flexible, light and are installed around large cables or busbars without disconnecting them. They also respond better than iron-core current transformers at high frequencies, which helps to measure harmonic currents. Janitza includes them in its MRG Flex cases with ranges of 100 to 4,000 A or 10 to 8,000 A depending on the model.

How long should a power quality recording last?

Janitza states that a measurement in accordance with the standard requires a recording of at least seven days. It matches the observation period of EN 50160. A shorter recording is useful to diagnose an event, not to conclude compliance.

What is the difference between the MRG 512-PRO PQ Flex and the MRG 96-PQ-L-LP Flex?

According to Janitza, the first integrates the UMG 512-PRO Class A, measures current harmonics up to the 63rd order, flicker and short interruptions, and includes a three-hour UPS backup. The second, about 3 kg and with a carrying backpack, measures current harmonics up to the 65th order and is aimed at analyzing disturbances and comparing meters.