Measurement to ENA Engineering Recommendation G5/5: What does it mean?

Outram’s PM7000 can now measure requirements for ENA Engineering Recommendation G5/5.

The latest Enhanced Harmonics upgrade available for the Outram PM7000 Power Quality Analyser enables companies wishing to agree new connection arrangements with their Distribution or Transmission Network Operator in the UK can now measure to ENA Engineering Recommendation G5/5 with a single measurement unit.

Although there may be years between updates to different Engineering Recommendations or Standards it is still difficult to know whether the one that you’re using is the latest.  Whether it’s making new connections, manufacturing new product or carrying out compliance measurements, it’s important that you keep up to date so that your latest innovations and your compliance measurements do so too.

One of the biggest difficulties when a new Standard or Recommendation is published is finding the equipment that will enable you to comply. Outram have been challenged recently finding test houses for their Real Time Fault Level Monitor – booking time in Australia for tests that cannot be performed anywhere else in the world due to its completely unique nature!

Since we understand these specific challenges well, we are pleased to announce that our PM7000 Power Quality Analyser with its Enhanced Harmonics option can measure all the Harmonics and other parameters required for the latest ENA Engineering Recommendation G5/5, which has superseded G5/4 since the 17th June 2020.

These measurements include:

  • Voltage Harmonics to the 100th order,
  • Current Harmonics to the 100th order,
  • THDv to the 100th Harmonic,
  • THDi to the 100th Harmonic,
  • Sub-groups & Interhamonics to the 100th Harmonic,
  • Event waveform capture on 7 triggers including voltage notches
  • 32 channels measuring detail down to single cycle without setting any thresholds, using Outram Research’s unique recording regime Single Cycle Adaptive Store™.

While we are in the process of writing a more in-depth review of the new recommendation, here are a few Frequently Asked Questions.

Do I need to report to EREC G5/5 straight away?

If you are measuring your network compliance for a connection agreed prior to 17th June 2020 then a G5/4 report should be sufficient, but for those connections agreements after 17th June 2020 (save for a potential grace period due to COVID-19 which may be offered to you by your Network Operator) you will need to comply with the new measurement requirements for G5/5.

What has changed from EREC G5/5 to G5/4 in terms of measurement?

  • Harmonic emissions or ‘pollution’ from more modern equipment has been seen to have been ‘squeezed up the tooth paste tube’ since no one was previously worried about harmonics above the 50th. As a result compatibility and planning levels have now been specified up to the 100th order harmonic. This also includes the need to measure Total Harmonic Distortion on Volts and Current to the 100th.
  • Planning and compatibility levels of some of these individual harmonic orders have been increased while none have been decreased.
  • Interharmonic and sub-group requirements have been revised as well as the depth and duration of Voltage Notches.
  • Resonant plant, including equipment that you might use to improve your on-site power quality such as Power Factor Correction, has now been specifically included in G5/5 since it may contribute to and amplify existing network distortion. There is now a simple assessment process for equipment connected at voltages below 33 kV but a more stringent one (captured in the Stage 3 process) above 33kV.
  • There is now a requirement for an accurate Fault Level Value of your network to produce the report since the Fault Level (strength of supply) directly relates to the impact current harmonic emissions may have on the voltage harmonics. For G5/4 the default value given was adequate but for G5/5 a more specific/accurate value is required either through Prospective Fault level Measurement or from the Network Operator.

For more details on these changes see our white paper on the differences between G5/4 and G5/5 here: G5_5 vs G5_4 Summary report Outram Research Ltd

Does the type of Voltage Transformer affect measurement of higher harmonics?

Depending on the transformer that you are measuring through, then yes there may be practical difficulties in measuring up to the higher harmonics. This is a result of unfaithful /less accurate transformation of the higher harmonics down from the primary voltage, not the accuracy of the PQ measurement device. While it is still possible to measure up to the 100th in these situations, the data may not be as meaningful, therefore it has been left to the discretion of the Network Operators as to whether they allow assessment of the harmonic measurement to just the 50th in some situations.

There may, however, be remedies for certain situations, for example, if measuring through a Capacitive Voltage Transformer (CVT), then BVM’s PQ Sensor is a transducer which provides an output signal that accurately reflects the harmonic and transient spectrum of the primary voltage all the way up to the 100th.

How do I carry out a measurement to EREC G5/5?

Customers are very welcome to hire out our PM7000s to carry out your own measurements, or they can choose for Outram’s fully qualified On-site Engineers to carry out the survey, producing a full report at the end of the measurement period. Contact us for prices and further information.

What if I need more than one point measured?

Outram have a hire fleet of over 30 PM7000 analysers, all capable of measuring to G5/5 requirements with a view to adding more, so we are well equipped to carry out measurements with a large number of analysers as well as hire them out as required.


See below for more specific detail on Outram’s Enhanced Harmonics Option:

Automatic and simultaneous measurement of harmonics*1 to the 100th on 6 inputs (V & I), and to the 50th on remaining 2 inputs as well as individual inter-harmonics between fundamental and second harmonics and inter-harmonic sub-groups to the 100th (3 x V only).

Individual harmonics, inter-harmonics, groups and sub-groups to the 127th harmonic on any phase can also be measured on detailed Adaptive Store channels. THD and THD Current also available to the 100th Harmonic.

*1As required by the EN61000-4-7 Class I and G5/5 Standards, harmonics recorded as General Parameters are Harmonic sub-groups comprising the Root Sum Square of the harmonic itself plus the two adjacent 5 Hz lines.