50 MHz Clip-Around Rogowski Probe For Clean Switching Current Waveforms
Power electronics demand accurate, non-intrusive current measurement at extremely high switching speeds. From wide-bandgap semiconductors to compact converters, engineers need current probes that can capture fast transients without distortion or noise pickup. This is where Rogowski Oscilloscope Current Probes such as the CWTMini50HF stand out.
What Is the CWTMini50HF Rogowski Current Probe?
The CWTMini50HF is a Rogowski Coil current probe that can be clipped around conductors and is designed to measure high frequency (AC) and switched DC currents. With a bandwidth of 50 MHz (-3 dB), thin shielded coils and good dV/dt immunity, this probe is intended for use in analyzing the fast switching characteristics of modern power semiconductor devices and converters.
Thanks to its innovative non-intrusive, flexible design, the CWTMini50HF can be used for measuring electrical signals directly from within a circuit, enabling users to perform diagnostics and testing with the aid of oscilloscopes, without having to break the circuits they are testing.
Why Rogowski Oscilloscope Current Probes Are Preferred
Non-intrusive and saturation-free measurements have become the norm for Rogowski Coil Current Probes, unlike other traditional current measurement equipment, which either uses current transformers or shunts and experience saturation with minimal insertion loss. Consequently, this kind of probe can be used effectively in high-current, fast-switching applications.
Due to its very high bandwidth (50 MHz) and very fast (12.5 ns) rise times, the CWTMini50HF accurately reproduces current waveform data as transmitted by MOSFET, IGBT, SiC and GaN devices, even in very high dV/dt operating situations.
The Rogowski coil has been designed to be electrically shielded from external interference caused by large rapid fluctuations in applied electric fields and transients. As such, these devices produce very clean and reliable measurement results.
Key Features of CWTMini50HF Current Probes
- Bandwidth: Up to 50 MHz (-3 dB)
- Rise Time: 5 ns (100 mm coil)
- Current Range: 30 A pk to 30 kA pk
- Shielded Rogowski Coil: Excellent dV/dt immunity
- Coil Sizes: 100 mm or 200 mm circumference
- Ultra-Thin Coil:
- 5 mm (2 kV pk insulation)
- 5 mm (5 kV pk insulation)
- Wide Temperature Range:
- Coil & cable: -40 °C to +125 °C
- Electronics: 0 °C to +40 °C
- Output: ±6 V pk into ≥100 kΩ (1 MΩ oscilloscope recommended)
Accuracy & Electrical Performance
- Accuracy: ±0.2% of reading (conductor centred)
- Linearity:05% of reading
- DC Offset: ±3 mV max at 25 °C
- Coil Voltage Rating:
- 2 kV pk (3.5 mm coil)
- 5 kV pk (4.5 mm coil)
- Cable Length: 1 m standard (longer on request)
Note: The CWTMini50HF is not recommended for driving 50 Ω loads
Battery & Power Options
Alkaline (B):
- 4 × 1.5 V AA batteries
- ~25 hours operation
Rechargeable (R):
- 4 × 1.2 V NiMH batteries
- ~10 hours operation
External power adaptor powers the unit and disconnects batteries (also trickle-charges NiMH).
Applications of Rogowski Coil Current Probes
Semiconductor Switching Analysis
- Measuring switching current waveforms and device losses
- Suitable for TO-247 MOSFETs and IGBTs
Power Converter Development
- Debugging and validation of inverters, converters, and SMPS
- Diagnosing snubber circuits, inductors, and capacitors
Mixed AC/DC Measurements
- Measuring small AC ripple currents in the presence of large DC currents
- Ideal for capacitor ripple current monitoring
High-Frequency & Transient Measurements
- Accurate capture of sinusoidal, pulsed, and transient currents
- Useful from power frequency to RF applications
Why Choose CWTMini50HF for Oscilloscope Current Measurement?
The CWTMini50HF gives engineers of high-frequency Power Electronics more accurate/intrusive modes of analysis than previously available with bandwidth and low noise interference to verify how accurately the device is switching without interference from test equipment or distorted waveforms.
Conclusion
To design and validate high-speed electronics (from switching devices to semiconductor devices), accurate current measurement is essential. With an increase in the number of switching frequencies and technologies like GaN and SiC, engineers much utilize Rogowski Oscilloscope Current Probes (ROCP) that offer high bandwidths, fast response times, and excellent immunity to electrical noise. The CWTMini50HF provides a 50 MHz bandwidth, an ultra-narrow shielded coil, and a non-intrusive Clip-Around Design, allowing for the clean and exacting measurement of fast transients and switching current results.
Measurements can avoid saturation issues while minimizing circuit disruptions; therefore, Rogowski coil current probes (CWT) provide current measurement solutions that will work now and in the future for applications such as semiconductor loss analyses to power converter diagnostic applications. Whether measuring low AC ripple currents or measuring high amplitude pulsed waveforms, the CWTMini50HF is capable of offering the accuracy and security needed in sophisticated R&D environments.
In India, as an authorized dealer of Power Electronic Measurements, Pantronics India supplies a full range of Rogowski Current Sensors that include CWT, CWT HF, CWT Mini, and CWT Ultra-Mini, and provides technical assistance to engineers to find appropriate current probe calibration equipment for routine conduct current measurement(s).
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
Rogowski Oscilloscope Probes measure high-voltage, low-frequency (HVLF) current AC, Pulsed or Rapid switching currents without physically breaking the circuit. As such, Rogowski Probes are ideal tools for the testing of Power/Power Electronics (e.g., Inverters) and for the Analysis & Testing of Semiconductors and their High Speed Switching (High-speed switching requires both a high bandwidth probe and high accuracy).
Unlike CTs, Rogowski Coil Current Probes will not saturate, and are capable of measuring very large AC and/or Pulsed currents over a wide frequency range. Whereas CTs are generally bulky and heavy, Rogowski Coil Probes are Lightweight, Flexible, and better suited for Fast Transient, and High-Frequency measurements.
The CWTMini50HF is designed for measuring AC and high-frequency Pulsed Direct Current (DC) currents. It has particularly good capabilities for accurately capturing the current waveform of DC-offset currents such as Ripple Currents in Capacitors or Switching Currents in Power Converters.
Yes! The CWTMini50HF has a bandwidth of 50 MHz and is designed with excellent immunity against dV/dt (rate of rise of voltage with time) enabling it to make rapid-switching measurements for both SiC (Silicon Carbide) and GaN (Gallium Nitride) Power Semiconductors.
Yes! The position of the magnetic field surrounding a conductor may have a significant influence (although Slight) on the accuracy of your measurements. For example, if the conductor is centred, accuracy would be ±0.2%, whereas if the conductor is off-centre, there may be a Typical variation of 1-2%. This will depend on the diameter of the conductor
Yes! The CWTMini50HF coil has a peak insulation value of up to 5kV depending on the thickness of the coil, and therefore can be safely used to measure current in high voltage power electronics.
The Rogowski coil and cable are rated for operational temperatures between -40 °C to +125 °C. This allows them to be used in both demanding lab and industrial settings, while the electronics associated with the Rogowski coils are rated to standard lab conditions.
You can find PEM Rogowski Oscilloscope Current Probes, including the CWTMini50HF, at Pantronics India, which is an authorized distributor for these products, offering local support and application assistance.
Expert Technical Support
CWTMini50HF 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)
Mail ID: s.joshi@pantronicsindia.com