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CWT and CWTHF Wideband ac current probes for high frequency ac current measurement. Many CWT are stocked, please inquire for the most suitable model

The CWT and CWTHF ac current probes operate LF-30MHz rugged clip-on flexible coil ac current probes, these probes work with any Data Aquisition (DAQ), scope or virtual oscilloscope.

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Model CWT and CWTHF clip-on ac current probe using Rogowski current sensing
  • Ac current bandwidth 1Hz to 30 MHz
  • CWT LF models available with extended LF bandwidth and low phase shift<1Hz
  • Models covering a 0.5A - 1200kA Amps range
  • 300:1 measuring range, example 300A CWT1B probe will measure 1A
  • 0.2% measurement accuracy
  • 10kV Insulation capability
  • Electrostatic screens (Models CWTHF)for HV and noisy systems
  • Flexible "clip-on" split-core ac sense coil
  • ±6V Instantaneous isolated output ideal for scopes, data loggers, PCI DAC cards, power analyzers
  • Uses 4 x AA batteries or 12V ac adapter (110V or 230Vac)
  • Traceable calibration certificate included
  • CE CA marked
  • Wide variety of models in stock

The CWT ac current probes are rugged clip-on flexible coil wideband ac current probes, based on tried and tested Rogowski Coil technology for wide bandwidth measurement and perfect conversion of current to voltage, intended for use with oscilloscopes, data loggers, transient recorders and power analyzers - ideally suited for power electronic applications. Based on the Rogowski principle, these probes have intrinsic high bandwidth performance and wide dynamic range allowing measurement of both small and large currents (1A-600kA) from 0.01Hz to 20MHz. The small coil profile (8mm dia), means the coil can be retrospectively installed without disruption to active power systems. As standard, the coil is insulated at 10kVrms, insulation can be increased if required. Models are available with a range of clip-around coil sizes to suit most conductors, allowing easy current monitoring even where access is limited.

Selection table for CWT range - these current probes have full 300:1 range

Specifications CWT Original Models
Type Sensitivity
(mV/A)		 Peak current Noise max*1
mV pk-pk		 Droop
typ.
(%/ ms)		 LF (3dB)
bandwidth
typ. (Hz) fL		 Peak di/dt
(kA/uS)		 Phase Lead
Degrees		 HF (-3dB) bandwidth
typ. (MHz) fH*2
Coil Length
300mm		 Coil Length
700mm
Standard Ranges of CWT .... measuring currents from 300mA
CWT/3N 20.0 3A to 600A 14 0.9 1.0 2.0 2.0@6kHz 10 5
CWT/6 5.0 6A to 1200A 12 0.9 1.9 8.0 2.0@4kHz 16 10
CWT/15 2.0 15A to 3000A 7.0 0.7 0.8 20 2.0@3kHz 16 10
CWT/30 1.0 3A to 6000A 3.5 0.5 0.6 40 1.9@2kHz 16 10
CWT/60 0.5 6A to 12000A 3.0 0.35 0.4 40 1.9@1kHz 16 10
CWT/150 0.2 15A to 30000A 3.0 0.2 0.2 40 1.0@300Hz 16 10
CWT/300 0.1 30A to 60000A 3.0 0.1 0.1 40 1.0@300Hz 16 10
CWTHF - Electrostatically Shielded Sensor / High Frequency Models ...from 150mA
CWTHF/015 200 0.15A to 30A 15.0 85.0 150 2.0 1.7 20 8
CWTHF/03 100.0 0.3A to 60A 11 78.0 105 4.0 1.7 20 8
CWTHF/06 50.0 0.6A to 120A 8.0 70 80 8.0 1.3 20 10
CWTHF/1 20.0 1.5A to 300A 6.0 50 50 20 0.9 20 10
CWTHF/3 10.0 3.0A to 600A 12.0 11.0 12 40 0.9 30 15
CWTHF/6 5.0 300A to 1,200A 12.0 5.5 6.0 80 0.9 30 15
CWTHF/15 2.0 15A to 3,000A 10.0 3.0 3.0 80 0.2 30 15
CWTHF/30 1.0 30A to 6,000A 10.0 1.5 1.5 120 0.1 30 15
CWTHF/60 0.5 60A to 12,000A 8.0 1.0 1.0 120 0.06 30 15
CWTHF/150 0.2 150A to 30,000A 5.0 0.8 0.8 120 0.06 30 15
CWTHF/300 0.1 300A to 60,000A 5.0 0.2 0.2 120 0.06 30 15
CWTHF/600 0.5 600A to 120,000A 5.0 0.06 0.05 120 0.06 30 15
CWTHF/1500 0.02 1500A to 300,000A 5.0 0.035 0.03 120 0.06 30 15

*1Distributed around the fL (3dB) bandwidth. Additional 50/60Hz noise of approximately 2mVpk-pk applies with AC 115V and 230V supplied CWT

*2The high frequency bandwidth is in part dependent on coil length. The values given are for a 700mm coil, a 300 –or- 500mm coil will have a higher fH

TYPICAL ACCURACY
(full scale)
Calibrated & traceable to UKAS ±0.2% with conductor central in the loop
Variation with conductor position in the coil loop typically ±1%
TYPICAL LINEARITY
±0.05% (full scale)
ABSOLUTE MAXIMUM VALUES OF di / dt (kA/µs)
(value must not be exceeded)
CWT (all models)
PEAK 40.0
RMS 1.5 @ 70℃
CWTHF/015 to CWTHF/1
PEAK 70.0
RMS 1.5 @ 70℃
CWTHF/3 to CWTHF/1500
PEAK 120.0
RMS 1.5 @ 70 ℃ (further information available on request)

Application

Typical uses

Power analyzers
Convenient method of extending the current, power and harmonic measurement range without bandwidth degradation. Excellent low frequency (0.06Hz) performance along with low phase shift <0.2deg
Motor drives and power electronic converters
Allows measurement of GaN, IGBT switching times, gate turn-on/turn-off times and peak current
AC Motors and generators, diagnostics, testing and installation
Easy retrospective installation of probes around conductors where regular clamp and split core CTs will not fit
Induction heating current control and diagnosis
Measurement of high current / high frequency signals, including high order harmonic effects
GaN and pulsed current applications
Semiconductor switches: IGBT, Power MOSfets, capacitor discharge and circuit breaker interruption currents
Capacitor discharge and lightning strike research
Measurement of transient and repetitive peak currents without opening conductors
Coil and cable
COIL CIRCUMFERENCE ‘A’ (mm)
300, 500, 700 or 1000mm
COIL CROSS SECTION ‘B’ (mm)
(dependent on "Peak coil voltage isolation" see below)
8.5 (supplied with 10kV insulation as standard)
14.0 (with protection sleeve)
PEAK COIL VOLTAGE ISOLATION (kV)
10

Safe peak working voltage to earth. The coils are flash tested at 15kVrms for 60 seconds. The coil is supplied with a removable silicone sleeve which provides additional mechanical protection.

TEMPERATURE RANGE (℃)
-20°C to 100°C

For de-rating due to temperature cycling please consult Powertek

CABLE LENGTH (metre) (from box to coil)
2.5 or 4
CWT Rogowski coil dimensions
Power input - mechanical - environmental
Power Supply
All CWT units are supplied with four AA batteries (typical life 90 hours) and a 12V-24Vdc input socket
A Universal Power adapter is included with the CWT probe (accepts 115Vac or 230Vac)
Rechargeable batteries and internal charger, option R, is available. (batteries are charged whenever external +12-24V dc supply is present). Typical recharge time 40 hrs, typical life 8 hrs.
INTEGRATOR BOX DIMENSIONS (mm)
H =183mm, W = 93mm, D = 32mm
OUTPUT SOCKET
BNC (output impedance 50 ohms- unit supplied with 0.5m BNC-BNC coaxial cable)
MIN. OUTPUT LOADING
100kohm (for rated accuracy), 50ohm drive capability optional.
TEMPERATURE RANGE (℃)
0℃ to +40℃
Ordering
Model
CWT unit is supplied with bnc-bnc cable, 12-24Vdc input, 4 AA batteries, power adapter and user manual, calibration certificate and carry case.
Cable length (m)
Coil circumference (mm)
e.g. order code = 6kApk, 4 AA Batteries, 12-24Vdc input, ac adapter, 2.5 metre cable, 500mm coil (Coil insulation is 10kV as standard)
CWT30B
2.5
500
e.g. order code = 6kApk, 4 AA Batteries, 12-24Vdc input, 230V ac adapter, 4 metre cable, 300mm coil
CWT30B
4
300
e.g. order code = 1.2kApk, 4 AA rechargeable batteries, internal battery charger, 12-24Vdc input, ac adapter, 2.5 metre cable, 500mm coil
CWT6R
2.5
500

All CWT current probes are supplied with bnc-bnc cable, 12-24Vdc input, 4 AA batteries, power adapter and user manual, calibration certificate and carry case. If you have any queries regarding the CWT or require specifications outside our standard ranges please do not hesitate to contact us.

Powertek specializes in the design and manufacture of electrical power, voltage and current measuring instrumentation
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