IEC 61000 is the master standard family for electromagnetic compatibility (EMC) — the ability of equipment to function correctly in its electromagnetic environment without introducing intolerable electromagnetic disturbances. It covers emissions (how much interference equipment generates) and immunity (how well equipment withstands interference). EMC compliance is mandatory for CE marking in the EU.
IEC 61000-2 Characterises electromagnetic environments (industrial, residential, light industrial). IEC 61000-2-4 defines compatibility levels for industrial installations — the reference for selecting surge arresters and filter ratings in process plant electrical design.
IEC 61000-3-2 Limits harmonic currents injected into the public supply by equipment ≤ 16 A/phase. Impacts variable speed drives (VFDs), UPS, LED drivers and switching power supplies — all major harmonic sources in process plants.
IEC 61000-3-3 Limits voltage fluctuations caused by equipment with varying current demand (motors, welders). Flicker (Pst, Plt) is the human perception metric for lamp flicker.
IEC 61000-4-2 Electrostatic discharge immunity test. Contact discharge up to 8 kV, air discharge up to 15 kV. Level 3 (6 kV/8 kV) is typical for industrial equipment in NAMUR/process environments.
IEC 61000-4-3 Radiated RF immunity — simulates the electromagnetic field from mobile phones, walkie-talkies, and wireless equipment operating near the device. 80 MHz to 6 GHz field. Level 3 (10 V/m) for industrial equipment.
IEC 61000-4-4 Electrical Fast Transient / Burst immunity — simulates interference from switching of inductive loads (contactors, relays) on power and signal cables. The most common cause of microprocessor crashes in industrial equipment.
IEC 61000-4-5 Surge immunity — simulates lightning-induced surges and switching transients on AC power lines. 1.2/50 µs voltage waveform, 8/20 µs current waveform. Level 3 (2 kV/1 kV) for industrial power ports.
IEC 61000-4-6 Conducted disturbance immunity induced by RF fields — 150 kHz to 80 MHz on power, signal and earth lines. Level 3 (10 V) is standard for industrial equipment.
IEC 61000-4-11 Tests equipment behaviour under voltage sags (dips), short interruptions and voltage variations — critical for assessing whether instruments and PLCs will maintain control during grid disturbances.
(THD) EMC (Electromagnetic Compatibility) means two things:
IEC 61000 is the foundational series covering both. For industrial plants, the IEC 61000-4 immunity tests are the most practically relevant — they replicate the real-world interference from contactors switching, VFDs running, lightning strikes, and RF transmitters.
| Test | Simulates | Typical industrial level |
|---|---|---|
| ESD (61000-4-2) | Static discharge from operator | Level 3: 6/8 kV |
| EFT/Burst (61000-4-4) | Contactor switching on cables | Level 3: 2 kV |
| Surge (61000-4-5) | Lightning, switching transients | Level 3: 2 kV/1 kV |
| Conducted RF (61000-4-6) | Nearby RF sources on cables | Level 3: 10 V |
| Radiated RF (61000-4-3) | Walkie-talkies, mobile phones | Level 3: 10 V/m |
| Voltage dips (61000-4-11) | Grid disturbances | Standard levels |
Variable speed drives (VFDs) are the primary source of harmonic disturbance in industrial plants. A 6-pulse VFD generates characteristic harmonics at orders 5, 7, 11, 13… An 18-pulse configuration or active front-end significantly reduces THD. IEC 61000-3-2 and plant studies (IEEE 519 in US practice) set the targets.
For equipment destined for the EU market, the EMC Directive (2014/30/EU) applies. The typical path: