G5: Harmonic Voltage
What is a G5?
A G5 assessment refers to the UK's Electrical Networks Association (ENA) Engineering Recommendation G5/5, a standard for assessing and limiting harmonic distortion when connecting new electrical equipment that has disturbing loads with harmonics emissions (like solar farms, battery storage, or large drives) to the distribution network, ensuring it doesn’t damage the network or negatively affect other users.
What does a G5 do?
The main purpose of G5/5 is to provide a set of design ‘limits’ for harmonic voltage levels that ensure the actual International Electrotechnical Commission (IEC) compatibility limits are not exceeded when new or additional load is connected.
Why are G5’s important?
The Distribution Network Operator (DNO) is responsible for the overall coordination of disturbance levels on its network and for assessing the impact of the new user’s relevant equipment. The new user is responsible for complying with conditions the DNO place on them to comply with this Engineering Recommendation and demonstrating compliance with G5/5.
When would a G5 assessment be required by SP ENW?
This is required for all generation applications with a total installation size above 50kW.
What types of assessment do SP ENW undertake?
We undertake the following initial stages assessments ‘in house’. This allow us to make a decision on whether a further detailed assessment is required.
Stage 1B, Stage 1C, Stage 2A: These stages are based on the size of the installation, compliance with IEC 61000-3-12 either under statement 1 or statement 2 (for Stage 1B), inverter technology type and voltage level.
What types of assessment do SP ENW NOT undertake?
1A – This is for up to 16A devices, we only carry out the G5 initial assessments for applications above 50kW/75A.
Stage 1D, 2B, 2C & Stage 3 are all based on measured background harmonics at the Point of Common Coupling (PCC). You’ll need to appoint a specialist at your own cost if the initial stages conclude that a detailed assessment is required. SP ENW will be able to provide you with the HV & LV fault levels that would be required by the appointed specialist.