A Practical Guide for Engineers Who Need Accurate, High-Speed Current Measurement
Struggling to measure fast-switching currents during EMC testing? Traditional current probes often can’t keep up. Rogowski coil current probes solve this problem — delivering wide-bandwidth, non-invasive AC current measurement from power electronics labs to full EMC compliance test suites. This guide covers everything you need to know, quickly.
What Is a Rogowski Coil Current Probe?
A Rogowski Coil is a flexible, air-core toroidal coil that wraps around a conductor to measure alternating current (AC) — without cutting the circuit. Unlike traditional current transformers, it has no iron core, so it never saturates. The result is accurate measurement across an enormous current and frequency range.
The coil’s output voltage is proportional to dI/dt. A built-in integrator converts this into a direct current reading on your Rogowski coil oscilloscope or power analyser — plug-and-measure, no circuit modification needed.
Key advantage: No saturation. Whether you’re measuring milliamps on a PCB or kiloamps in an industrial drive, the Rogowski AC Current Probe handles it cleanly.
Why Use a Rogowski Coil Probe for EMC Testing?
EMC testing demands current probes that capture full harmonic content, survive high dI/dt transients, and fit awkward geometries. Here’s why the Rogowski coil probe wins:
- Wide bandwidth (up to 50 MHz) — captures full harmonic spectrum of switching waveforms
- No magnetic saturation — ideal for high-current EMC measurements
- Flexible coil — fits around busbars, cable bundles, and PCB traces
- Galvanic isolation — safe on live, high-voltage conductors
- Non-intrusive — doesn’t disturb the circuit under test
Whether you’re performing conducted emissions testing, characterising switching transients, or measuring common-mode current on cable harnesses, the Rogowski coil current probe delivers the measurement accuracy EMC engineers need. Learn more at pantronicsindia
Using a Rogowski Coil with Your Oscilloscope
Setting up a Rogowski coil oscilloscope measurement takes minutes:
- Connect the integrator/amplifier unit to your oscilloscope via BNC cable
- Wrap or clip the flexible Rogowski coil probe around the target conductor
- Set oscilloscope input to match the probe output (mV/A or V/A sensitivity)
- Trigger as normal — read current directly in amps
PEM UK‘s CWT range of Rogowski AC Current Probes are engineered specifically as oscilloscope probes, covering 100 mA to over 300 kA from <0.1 Hz to 50 MHz. Each probe ships calibrated and ready to use.
Which Rogowski Coil Probe Is Right for You?
Rogowski coil current probes in the CWT range, each optimised for different EMC scenarios. The table below compares key specifications to help you choose:
| Model | Bandwidth | Coil Length | Peak dI/dt | Current Rating | Best For EMC |
|---|---|---|---|---|---|
| CWTMini50HF | 50 MHz | 110 mm | 5,000 A/µs | 0.1 A – 1.5 kA | EMC / HF switching |
| CWTHF | 30 MHz | 150 mm | 1,500 A/µs | 0.5 A – 10 kA | Power electronics EMC |
| CWTMini | 16 MHz | 110 mm | 400 A/µs | 0.1 A – 1.5 kA | General EMC lab use |
| CWT Ultra-mini | 16 MHz | 90 mm | 400 A/µs | 0.1 A – 800 A | PCB / tight spaces |
| CWTUM-S | 16 MHz | 90 mm | 400 A/µs | 0.1 A – 800 A | Space-constrained EMC |
| CWTUM-F | 30 MHz | 90 mm | 800 A/µs | 0.1 A – 800 A | Forked / busbar EMC |
| CWT | 16 MHz | 150 mm | 400 A/µs | 0.5 A – 30 kA | Standard industrial EMC |
| CWTLF | 1 MHz | 150 mm | 100 A/µs | 1 A – 300 kA | Low-frequency / high current |
* Operating Temperature: All CWT models — -40°C to +85°C (electronics unit). Suitable for industrial and laboratory EMC environments.
For EMC pre-compliance and high-frequency switching analysis, the CWTMini50HF (50 MHz bandwidth) is the top pick. For high-current industrial drives, choose the CWTLF. For space-constrained PCB work, the CWT Ultra-mini or CWTUM-S fits perfectly
Common EMC Use Cases for Rogowski Coil Probes
- Conducted emissions measurement on power lines — wide bandwidth captures full harmonic content
- Switching transient analysis in inverters, motor drives, EV powertrains
- Common-mode current measurement on cable bundles for radiated emissions diagnosis
- EMC filter validation under real operating conditions at full load
- Pre-compliance testing to identify noise sources before formal lab testing
Rogowski coil probes are equally at home in solar inverter characterisation, EV drivetrain EMC, UPS systems, and industrial automation — wherever fast switching currents need accurate, non-invasive measurement
Pantronics India — Authorised Distributor for PEM UK in India
Pantronics India is the authorised distributor of PEM UK Rogowski coil current probes across India. Pantronics supplies world-class power electronics components and measurement solutions to industries including automotive, renewable energy, industrial automation, power conversion, and research & development.
Indian engineers and EMC labs can source the full PEM UK CWT range — including the CWTMini50HF, CWTHF, CWT Ultra-mini, and more — directly through Pantronics India, backed by local technical support and fast delivery. Pantronics also provides application guidance for integrating Rogowski AC Current Probes into your specific EMC test setup.
Conclusion
The Rogowski coil current probe is the most versatile tool in the EMC engineer’s kit — wide bandwidth, no saturation, safe on live conductors, and fast to deploy with any Rogowski coil oscilloscope. PEM UK’s CWT range covers every EMC scenario from bench-top pre-compliance to full industrial characterisation.
Explore the full CWT range at Pantronics india
Frequently Asked Questions (FAQ)
Below are the most common questions engineers and technicians ask about using a Rogowski coil current probe for EMC testing and compliance work.
A Rogowski coil current probe is a flexible, air-core coil that wraps around a conductor and measures AC current without breaking the circuit. It senses the rate of change of current (dI/dt) and feeds this signal through a built-in integrator to produce a calibrated voltage output — readable directly on an oscilloscope or power analyser as amps
Hall-effect probes use a magnetic core that saturates at high currents and typically have limited bandwidth (a few hundred kHz). A Rogowski coil probe has no iron core — so it never saturates — and covers bandwidths up to 50 MHz. This makes it far superior for capturing the high-frequency harmonic content and fast switching transients that EMC testing demands.
For EMC pre-compliance work involving high-frequency switching (SiC, GaN, IGBT), the CWTMini50HF is the first choice — it delivers 50 MHz bandwidth and 5,000 A/µs dI/dt. For standard power electronics EMC, the CWTHF (30 MHz) or CWTMini (16 MHz) handle most lab scenarios. For high-current industrial drive testing, the CWTLF covers up to 300 kA.
The CWT range covers current from 100 mA (CWT Ultra-mini, CWTMini) up to 300 kA (CWTLF), and frequencies from below 0.1 Hz up to 50 MHz (CWTMini50HF). This makes the CWT family suitable for everything from PCB-level signal diagnostics to high-power industrial EMC characterisation — all with a single probe family.
No. Rogowski coil probes are AC-only instruments — they measure the rate of change of current (dI/dt), which is zero for steady DC. They are, however, excellent for measuring AC ripple superimposed on a DC bus, and many CWT models operate from below 0.1 Hz — covering very low frequency AC components that most probes miss.
All CWT electronics units are rated for -40°C to +85°C, making them suitable for harsh industrial field environments as well as laboratory use. This wide temperature range ensures reliable EMC measurement performance across automotive test chambers, outdoor renewable energy installations, and factory environments.
Need current probe assistance?
Get expert guidance on Rogowski coil current probes — from probe selection and EMC test setup to compliance testing and application support for power electronics, EV systems, and industrial automation.
Ms. Sunita Joshi (Current Probe Expert)
Mail ID: s.joshi@pantronicsindia.com