For charging modules, harmonic current compliance is a critical aspect of technical evaluation. Specifications frequently reference two standards: IEC 61000-3-2 and IEC 61000-3-12.
The distinction between these two standards hinges on the equipment's rated single-phase input current. However, simply determining whether the measured current exceeds 16 A is often insufficient.
This article explains how to identify the applicable standard and highlights key points that buyers of charging modules should focus on when requesting harmonic test reports.
IEC 61000-3-2 vs IEC 61000-3-12
The two standards address harmonic currents injected by electrical and electronic equipment into public low-voltage power systems, but they cover different input-current ranges.
IEC 61000-3-2:2018, including its 2024 amendments, applies to equipment with a rated input current up to and including 16 A per phase. IEC 61000-3-12:2011+A1:2021 applies to equipment with a rated input current above 16 A and up to 75 A per phase.
For three-phase EV charging equipment, this distinction becomes particularly important because charging modules can quickly move beyond the 16 A range as output power increases.
How to Estimate the Input Current of a Charging Module
For a three-phase charging module, the approximate input current can be calculated as:
Iin = Pout / (√3 × VLL × η × PF)
Where:
- Iin = AC input current per phase
- Pout = DC output power
- VLL = three-phase line-to-line input voltage
- η = module efficiency
- PF = input power factor
For example, consider a 30 kW three-phase charging module operating at:
- Input voltage: 400 VAC L-L
- Efficiency: 95%
- Power factor: 0.99
- Output power: 30 kW
The estimated input current is:
- Iin = 30,000 / (1.732 × 400 × 0.95 × 0.99)
- Iin ≈ 46 A per phase
This is clearly above 16 A and within the >16 A to 75 A range covered by IEC 61000-3-12.
Which modules are rated below 16A?
Regarding the module brands currently on the market—taking Infy Power as an example—basically only 10kW charging modules operate at currents below 16A, whereas modules rated at 20kW and above all exceed 16A.
The approximate input current at different output powers would be:
These figures are illustrative calculations using the assumptions above, not the rated current of a specific charging module.