PEM CWT Ultra Mini ‘Forked’ (CWT UM-F / CWT UMHF-F) AC Current Probe
The PEM AC Current Probes utilize a Rogowski Coil and Matched Analog Integrator to provide accurate non-contact, measurement of AC currents over a very broad frequency range. These flexible “clip-around” Current Probes have very low insertion impedance compared to Current Transformers, (CT), or Hall Current Transducers, are easy to insert in confined spaces and are not damaged by over-current surges. They can be used for measuring ac, pulse or transient current waveforms. Since the PEM Current Probes have no magnetic core they can be used to measure ac current on a conductor with high dc current or in the presence of a high dc magnetic field.
The novel ‘forked’ construction with a coil length of 55mm.
The CWTUM-F (1.2mm thickness) and the electrostatically screened version, the CWTUMHF-F (1.7mm thickness), are an extension of the original CWT Ultra-mini range from PEM. The novel mechanical construction can reduce overall Rogowski coil size and thus the probes impact on the circuit under test. This simplifies measurements in densely populated power electronic circuits.
Features
- Novel ‘forked’ construction with a coil length of 55mm.
- Wide operating temperature -40°C to +125°C.
- Current ratings from 60A pk to 12kA pk.
- Coil insulation 1.2kV pk.
- Peak di/dt capability up to 100kA/μs.
- Thin version 1.2mm cross section diameter.
- HF (-3dB) 20MHz
- A shielded ‘HF’ version 1.7mm cross section diameter.
- Excellent voltage immunity
- HF (-3dB) 30MHz
Applications
- Switching current waveforms in power electronic circuits:
- MOSFET or IGBT devices as small as TO-220, D2PAK and other SMT power devices.
- Measuring power losses in semiconductor bond wires in power devices.
- Monitoring currents in small inductors, capacitors, snubber circuits, etc.
- Measuring small AC currents in the presence of large DC currents (e.g. monitoring capacitor ripple).
- Power converter development and diagnostics.
- Measuring high frequency sinusoidal, pulsed or transient currents in power frequency to rf applications.
Tech Support
- CWT Ultra Mini ‘Forked’ (CWT UM-F / CWT UMHF-F) Datasheet – 2024
- CWT/LFR-YK Power Cable, 0.5m , For Yokogawa Oscilloscopes and ScopeCorders
Instructions for Use
Mechanical Dimensions
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- CWT Application Notes
- CWT Technical Note – Delay and Rise Time
- CWT Technical Note – Low Frequency Performance
- Voltage Immunity
- Accurate Power Conversion Measurements on High Power Motor Drives
- Instructions for CWT Integrator Module Fuse Replacement
- CWT Ultra Mini Accuracy Notes
- CWT Ultra Mini Technical Note – High Frequency
- Temperature testing Ultra-mini Coil
- Application Note – CWT AC Current Probes – what is minimum recommended current?
- Application Note: Transducer Termination Impedance – Low and High Frequency Analysis
- PEM CWT AC Current Probes (Rogowski Coils) – Equivalents
- “High Performance Rogowski Current Transducers”, W. F. Ray and C. R. Hewson
- “Next-Generation Current Probes for High-Speed and High Power-Density Applications”, Dr Chris Hewson, Power Electronic Measurements Ltd
- “Power Integrity” by Steve Sandler. See Chapters 5: Probes and 7: Measuring Impedance for applications using PEM Rogowski Coils (purchase of book required).
- CWTUM Gain and Phase Error Charts
- Measuring Fast Switching Currents with CWT UM, CWT Mini and CWT MiniHF, Dr Chris Hewson, APEC 2015
Pricing
Product Configurator:
Select product options from drop-down menus to quote standard products not normally in stock. For fully custom products, fill in the message box below.
Order Code for CWT Ultra Mini: Type / Battery / Cable Length / Coil Circumference
For example: CWT UM/015/B/1/80
For descriptions of the possible selections, please see the Specifications above.
CWT Ultra Mini 'Forked' AC Current Probe
| Part No. | Description | Price | In Stock |
|---|---|---|---|
| CWT UMHF-F/30/B/1/55 | AC Current Probe, Ultra-mini -HF ‘Forked’, 1.0mV/A, 6.0kA, 2.6Hz-30MHz, Alkalai battery 4xAA, 1m cable length from Coil to Integrator, 55mm Coil length, 1.7mm cross section. Includes US13S power supply. | $1,410.00 | |
| CWT UMHF-F/1/B/1/55 | AC Current Probe, Ultra-mini -HF ‘Forked’, 20mV/A, 300A, 50Hz-30MHz, Alkalai battery 4xAA, 1m cable length from Coil to Integrator, 55mm Coil length, 1.7mm cross section. Includes US13S power supply. | $1,410.00 | |
| CWT UMHF-F/03/B/1/55 | AC Current Probe, Ultra-mini -HF ‘Forked’, 100mV/A, 60A, 150Hz-30MHz, Alkalai battery 4xAA, 1m cable length from Coil to Integrator, 55mm Coil length, 1.7mm cross section. Includes US13S power supply. | $1,410.00 |
CWT Ultra Mini Accessories
| Part No. | Description | Price | In Stock |
|---|---|---|---|
| US13S | CWT UM Regulated Power Supply. 120VAC, 60Hz, 12V ±10%, 300mA, Barrel type: 1.3 x 3.5 x 10mm. Power disconnects battery when plugged into the integrator. | $40.00 | |
| EU13S | CWT UM Regulated Power Supply. 100V-220AC, 50/60Hz, 12V ±10%, 500mA, Barrel type: 1.3 x 3.5 x 10mm. Power disconnects battery when plugged into the integrator. European plug type. | $40.00 | |
| UK13S | CWT UM Regulated Power Supply. 100V-220AC, 50/60Hz, 12V ±10%, 500mA, Barrel type: 1.3 x 3.5 x 10mm. Power disconnects battery when plugged into the integrator. UK plug type. | $40.00 | |
| PowerCableYK13 | Yokogawa compatible power cord, 0.5m, supports all PEM units fitted with a 1.3mm DC power socket. | $70.00 |
Re-Calibration
Note: Calibration on new product is discounted 50%.
New PEM Rogowski Coils include a Manufacturer’s Calibration Certificate at no extra charge.
| Part No. | Description | Price | In Stock |
|---|---|---|---|
| OL-17025-500A-AC | 17025 Accredited Calibration, Current Transducer, Full-scale Range between 0 and 500Arms, 50-400Hz, https://gmw.com/quality/ | $300.00 | |
| OL-17025-500A-AC-ADD | Calibration of Additional Transducer | $150.00 | |
| OL-17025-2000A-AC | 17025 Accredited Calibration, Current Transducer, Full-scale Range between 501 and 2000Arms, 50-400Hz, https://gmw.com/quality/ | $400.00 | |
| OL-17025-2000A-AC-ADD | Calibration of Additional Transducer | $200.00 | |
| OL-17025-8000A-AC | 17025 Accredited Calibration, Current Transducer, Full-scale Range between 2001 and 8000Arms, 50-400Hz, https://gmw.com/quality/ | $500.00 | |
| OL-17025-8000A-AC-ADD | Calibration of Additional Transducer | $250.00 |
Repair
| Part No. | Description | Price | In Stock |
|---|---|---|---|
| RECOIL-CWT | Recoil (replace damaged coil) and Recalibrate
| $820.00 |
Terms and Conditions
Quantity Discount Schedule:
| Quantity | 1 – 9 | 10 – 24 |
| Discount | 0% | 5% |
Terms and Conditions:
Prices above are for domestic deliveries to Canada, USA and Mexico only.
Prices are expressed in U.S. Dollars, FCA San Carlos, California.
Prices are subject to change without notice.
Higher quantity and OEM discounts are available.
Payment:
Visa, MasterCard, Amex, Prepayment before shipment, or Net 30 days (subject to credit
acceptance).
Delivery:
Items in stock shipped next business day. All other items are 8-10 weeks.