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Powertek

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CWT Mini HF - Rogowski coil current sensor

Miniature wideband current probe for current measurement

The CWT Mini HF current probes utilize a high performance Rogowski Coil sensor thin enough (typical cross section 3.5mm) to fit in very confined spaces - often between the legs of a semiconductor power switching device.

With high frequency bandwidths up to 30MHz, the CWT Mini HF Rogowski coil is ideal for measuring switching transients or pulsed currents starting at 300mA up to 300kA in power electronic equipment. The CWT Mini HF Rogowski probe is a clip around flexible coil current probe based on the Rogowski principle to achieve high bandwidth measurement and faithful conversion from current to voltage, intended for use with oscilloscopes, data loggers, power meters and power analyzers. Available with a 100mm or 200mm length clip-around coil, ensuring easy current monitoring even where access is limited.

CWT Mini HF Rogowski Coil

LFR

The New CWT Mini HF combines an innovative screened Rogowski coil providing excellent immunity to interference from fast local dV/dt transients or large 50/60Hz voltages and an extended 30MHz (-3dB) high frequency bandwidth for 100mm coils. The coil has a wide operating temperature from -40°C to +125°C and is available with 5kV peak insulation, 4.5mm thickness.

The CWT Mini HF Rogowski coil range from Powertek, combines state of the art performance of the CWT ac current probe but features a miniature clip around Rogowski coil capable of monitoring currents in even the most difficult to reach areas of the circuit.

  • A Novel electrostatic shielded Rogowski coil providing excellent immunity to interference from fast local dV/dt transient or large 50/60Hz voltages
  • Extended (-3dB) high frequency bandwidth 30MHz for a 100mm coil
  • Peak di/dt capability up to 100kA/µs
  • Wide operating temperature from -40°C to +125°C
  • 4.5mm thick Rogowski coil with 5kV peak insulation

Full specifications for the CWT Miniature HF Rogowski coil range are available in CWTmini-hf Datasheet

Available kA Peak Current ratings 0.03, 0.06, 0.15, 0.3, 0.6, 3.0, 6.0, 12, 30, 60, 120, 300

Sensitivity set to give ± 6 volts peak output (e.g. 1.0mV/A for ± 6000A peak)

Typical Bandwidth 0.1Hz to 30MHz

Accuracy typically 2% of reading

DC offset no greater than 2mV

Thin flexible clip-around coils

  • Coil lengths of 100 and 200mm
  • Rogowski Coil cross sectional diameter 4.5mm for 5kV isolation
  • Peak voltage isolation 5kV

Cable length - The cable connecting the cable to the integrator box comes in lengths from 1m, 2.5m or 4m.

Integrator power supply


Either:

    Battery 4 AA 1.5V standard alkali batteries typical life 25hrs plus- 2.1mm/2.5mm socket for 12 to 24V DC input (batteries inoperative when DC supply present)

Or:

  • Rechargeable NiMH Batteries typical life 10hrs plus- 2.1mm/2.5mm socket for 12 to 24V DC input (batteries trickle charged when DC supply present) An AC/DC adapter is included for use with the CWT details can be found in:

CWT Mini HF Rogowski Coil Models and Specifications

Model Sensitivity
(mV/A)
Peak current*1
(kA)
Noise max*2
(mV pk-pk)
Droop
%/mS
LF (3dB)
bandwidth typ.
(Hz) FL
Peak di/dt
kA/µs
HF (3dB) bandwidth*3
MHz
Coil Length 100mm Coil Length 200mm
CWT Mini HF 015 200 0.03 15 85 150 2.0 30 23
CWT Mini HF 03 100 0.06 11 78 100 4.0 30 23
CWT Mini HF 06 50 0.12 8.0 70 75 8.0 30 23
CWT Mini HF 1 20 0.3 6.0 53 50 20 30 23
CWT MiniHF 3 10 0.6 10 11 12 40 30 23
CWT Mini HF 6 5.0 1.2 10 5.5 6.0 80 30 23
CWT Mini HF 15 2.0 3.0 8.0 2.8 3.0 80 30 23
CWT Mini HF 30 1.0 6.0 8.0 2.8 3.0 100 30 23
CWT Mini HF 60 0.5 12.0 6.0 1.0 1.0 100 30 23
CWT Mini HF 150 0.2 30.0 4.0 1.0 1.0 100 30 23

*1. Higher current ratings are available, CWT300 Peak current 60kA, CWT600 Peak current 120kA, CWT1500 Peak current 300kA etc

*2. Noise max. is the internally generated noise which is at a maximum at LF(-3dB) bandwidth

*3. The High Frequency HF(-3dB) is quoted for a 2.5mm cable between coil and integrator

TYPICAL ACCURACY
(full scale)

Calibrated to UKAS ±0.2% with conductor central in the loop
Variation with conductor position in the coil loop typically ±2%

TYPICAL LINEARITY

±0.05% (full scale)

ABSOLUTE MAXIMUM VALUES OF di / dt (kA/µs)
(value must not be exceeded)

PEAK

PEAK 100kA/uS

All models 1.2kA/uS

Coil and cable
COIL CIRCUMFERENCE ‘A’ (mm)
100 or 200mm optional lengths to 1000mm
COIL CROSS SECTION ‘B’ (mm)
4.5mm for 5kV isolation
PEAK COIL VOLTAGE ISOLATION (kV)
5kV

Safe peak working voltage to earth. 5kV coils are flash tested at 8kVrms/60Hz for 60 seconds. Information about the continuous use of coils at high voltage can be obtained from Powertek

TEMPERATURE RANGE (°C)
-40°C to 125°C

For de-rating due to temperature cycling please consult Powertek

CABLE LENGTH (metres) (from box to coil)

1m, 2.5m or 4m.
Max cable length for CWT015 is 1m, CWT03 is 1.5m, CWT06 is 2.5m

Power input - mechanical - environmental
POWER SUPPLY

All CWT units are supplied with four AA Lithium batteries (typical life 90 hours) and a 12V-24Vdc input socket and a power adapters (AC to 12Vdc), to power the CWT from 230Vac or 115Vac. Specify adapter type, 230V or 115 V

Rechargeable batteries, option R, are available. (batteries are charged whenever external +12V dc supply is present). Typical recharge time 40 hrs, typical life 8 hrs.

INTEGRATOR BOX DIMENSIONS ntegrx 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
100k (for rated accuracy).
TEMPERATURE RANGE (°C)
0°C to 40°C
Model
See table above

CWT Mini HF 06

Power Option
B-Battery
R-Rechargeable

R

Cable Length (m)
1, 2.5 or 4
(custom length available)

2.5

Cable Length (mm)
100 or 200
(custom length available)

100

Insulation(kV)
5

5

i.e. A CWT MiniHF, peak current 120A, Rechargeable battery, 2.5m cable, 100mm circumference coil, 5kV peak coil, 4.5mm thick
All units are supplied with user manual, factory calibration, hard carry case, 0.5m BNC-BNC output cable

If you have any queries regarding the CWT or require specifications outside our standard ranges please do not hesitate to contact us.