CWTHF Rogowski Oscilloscope Current Probes for High-Frequency Power Electronics Measurement
One of the most challenging aspects of developing modern electronics is accurately measuring fast, transient current waveforms. Engineers today require current probes that offer a unique trifecta: wide bandwidth, superior noise immunity, and non-invasive measurement.
CWTHF Rogowski Oscilloscope Current Probes are the industry standard for capturing fast, rapid current waveforms in modern power electronics. These capabilities are critical for applications ranging from wide-bandgap (SiC/GaN) semiconductor switching and EMC testing to pulsed power systems. By using CWTHF Rogowski Oscilloscope Current Probes, engineers can achieve precise 30 MHz bandwidth measurements with high dV/dt immunity. Engineered specifically for these rigorous environments, the CWTHF range features patented electrostatic shielding to ensure total signal integrity during wide-bandgap semiconductor testing and pulsed power measurements.
What Are CWTHF Rogowski Coil Current Probes?
CWTHF probes are shielded, high-frequency Rogowski coil current probes developed by PEM Ltd, pioneers of wide-band Rogowski technology for over 30 years.
Unlike conventional current transformers or shunt resistors, Rogowski coil current probes are:
- Non-intrusive: No need to break the circuit or add significant impedance.
- Core-less Design: Eliminates magnetic saturation, allowing for accurate measurement of huge currents in small form factors.
- High Fidelity: Capable of reproducing the incredibly fast switching waveforms found in modern power converters
The CWTHF is the high-frequency evolution of the CWT platform, featuring a patented electrostatic shield for industry-leading noise rejection.
Why Choose CWTHF Current Probes?
➤ Superior Noise Immunity (Electrostatic Shielding)
In high-power environments, dV/dt interference can ruin measurement accuracy. The CWTHF’s unique shield protects the coil from:
- 50/60Hz electromagnetic fields.
- Voltage spikes from rapidly changing loads.
- High dV/dt noise during high-speed circuit switching.
➤ Wide Bandwidth (30 MHz)
With a frequency range extending from 0.03 Hz to 30 MHz, these probes can capture:
- Sinusoidal and quasi-sinusoidal AC.
- Complex Pulse Width Modulation (PWM) signals.
- High-speed transient pulses.
➤ Massive Dynamic Range
- Peak Currents: 30 A up to 300 kA.
- Max di/dt: Rated up to 120 kA/µs.
CWTHF Rogowski Oscilloscope Current Probes are ideal for use in the testing of high-power converters, fault current measurements, and for pulsed power systems.
Key Features of CWTHF Rogowski Coil Current Probes
➤ Thin, Flexible, Clip-Around Design
- Easy-to-use clip-around Rogowski coil
- 5 mm max coil cross-section for tight spaces
- Flexible coil fits around large or irregular conductors
➤ High Voltage Insulation
- 10 kV peak coil insulation
- Verified by 15 kV rms, 60-second withstand test
- Removable silicone sleeve for added mechanical protection
➤ Minimal Circuit Loading
- Loads the circuit under test by only a few pH
- Ensures accurate waveform capture without system disturbance
➤ Customisable Coil and Cable Lengths
- Standard coil lengths: 300 mm, 500 mm, 700 mm, 1000 mm
- Standard cable lengths: 1 m, 2.5 m, 4 m
- Longer lengths available on request for large installations
Technical Specifications (CWTHF Models)
➤ Output
- ±6 V peak at rated peak current into ≥ 100 kΩ
(Recommended for 1 MΩ oscilloscope inputs) - ±2 V peak into 50 Ω (015HF to 150HF models only)
➤ Accuracy and Linearity
- ±0.2 % of reading (conductor centred)
- ±1 % typical due to conductor position
- Linearity: 0.05 % of reading
➤ DC Offset and Temperature
- DC offset: ±3 mV max at 25 °C
- Coil & cable: –20 °C to +100 °C
- Integrator electronics: 0 °C to +40 °C.
➤ Power Options
- Alkaline: 4 × AA, ~25 hours operation
- Rechargeable NiMH: 4 × 1.2 V, ~10 hours operation
- External adaptor powers unit and charges batteries (R version)
Applications of CWTHF Current Probes
CWTHF Rogowski Coil Current Probes are widely used in:
- Power electronic switching circuit transient measurement
- Power converter development and diagnostics
- EMC testing in traction systems and motor drives
- High-frequency sinusoidal currents (e.g. induction heating)
- Measuring small AC ripple currents with large DC offsets
- Lightning strike and fault current measurement
- Pulsed power and high-energy systems
Conclusion
CWTHF Rogowski Oscilloscope Current Probes set the benchmark for high-frequency, non-intrusive measurement. By combining shielded coil technology with flexible installation, they provide reliable data in “noisy” environments where conventional probes fail.
Pantronics India, an authorized distributor of Power Electronic Measurements (PEM), provides the full range of Rogowski sensors including the CWT, CWTHF, CWT Mini, and CWT Ultra-mini. For engineers in India seeking professional application support and precise current measurement tools, Pantronics India Pvt Ltd is your trusted partner.
For engineers seeking accurate, wide-band Rogowski Coil Current Probes and professional application support in India, Pantronics India Pvt Ltd is your trusted partner
Frequently Asked Questions
A Rogowski probe uses an air-cored coil to measure the rate of change of current (di/dt). This produces a voltage which is then processed by an integrator to provide a voltage output directly proportional to the current. Because it has no iron core, it cannot saturate, making it perfect for high-current transients.
Standard current transformers often suffer from phase shifts and saturation at high frequencies or high currents. The CWTHF’s core-less design and electrostatic shield allow it to maintain a flat frequency response up to 30 MHz while ignoring the electrical noise (dV/dt) typical of high-speed switching.
No, Rogowski coils are inherently AC-coupled devices. However, they are excellent at measuring small AC ripple currents riding on large DC offsets, which is a common requirement in DC-DC converter testing.
Expert Technical Support
CWTHF Rogowski Oscilloscope Current Probes at Pantronics India are supported by experienced application professionals for high-frequency, high-dV/dt power-electronics measurements.
Ms. Sunita Joshi (Passive Components & Test & Measurement Expert) 
s.joshi@pantronicsindia.com