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Products > Probes > CWT Ultra Mini AC Current Probe
NEW Non-Invasive Measurement Information
CWT Ultra Mini AC Current Probe
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Download the product spec sheet here. | Visit the "Support Page" for more downloads.

What's included:
Rogowski AC Current Probe
1 meter cable
0.5m BNC:BNC cable
Alkalai battery 4xAA
User manual
1 Year Warranty

Model Description Price  
CWT UM/015/B/1/80 AC Current Probe 200mV/A, 30A, 116Hz-30MHz, 1m cable, 80mm Coil, 0.5m BNC-BNC output cable
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.
  • Product Information
  • Detailed Specifications
  • Applications
The CWT Ultra-mini has an extremely thin, clip-around Rogowski coil of typically 1.6mm cross-section. Such a thin coil enables currents to be measured in the most difficult to reach parts of a power electronic converter with negligible disruption to the circuit under test.

  • Expanded operating temperature range -40ºC to +125ºC
  • Extended (-3dB) bandwidth from a few Hz to 30MHz
  • Current ratings from 30Apk to 6000Apk
  • Improved peak di/dt capabilities up to 70kA/μs
  • 1.7mm (max) cross section, flexible, clip-around coil
  • ±6V into 1MΩ, and 50Ω drive capability
  • Loads the circuit under test by only a few pH
  • Positional accuracy typically ±2%

Performance Characteristics Rating
Sensitivity 200mV/A
Peak current 30A
Noise maximum 20mVp-p
Droop 80%/ms
LF (-3dB) bandwidth 116Hz
Peak di/dt 2.0kA/μs
HF (-3dB) bandwidth 30MHz
Output ±6V peak corresponding to ‘Peak Current’ into ≥ 100kΩ
(e.g. DC 1MΩ oscilloscope)
±2V peak at half ‘Sensitivity’ into 50Ω (for long output cables)
Accuracy Variation with conductor position in the coil typically ±2% of reading (for a 2mm² conductor)
Linearity (with current magnitude) 0.05% of reading
Calibration Calibrated to ±0.2% reading with conductor central in the coil loop
DC offset ±3mV maximum at 25°C
Temperature Coil and cable -40°C to +125°C. Integrator 0 to +40°C
di/dt ratings These are ‘Absolute maximum di/dt ratings’ and values must not be exceeded:
Absolute max. peak di/dt: 70kA/μs
Absolute max. rms di/dt: 1.0kA/μs (1.2kA/μs for models CWT1 and above)
Coil voltage 1.2kVpeak. Safe peak working voltage to earth. Rating established by a 3kVrms, 50Hz, 60sec flash test
Coil circumference 80mm
Coil cross section 1.6mm
Output connector BNC (0.5m BNC - BNC cable included)

The specifications are subject to change without notice.

Caution: To avoid equipment damage and/or severe injuries death or death do not use this probe close to voltages higher than 50 VAC or 75 VDC.

Applications include measuring:
  • Switching current waveforms in power electronic circuits, for example
    • in MOSFET or IGBT devices as small as TO-220 or TO-47
    • in bond wires in power devices
    • to measure power losses in semiconductors
    • 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
  • Measuring high order harmonics