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A wide range of rugged clip around flexible coil current probes using Rogowski Coil technology for wide bandwidth measurement and faithful conversion of current to voltage, intended for use with oscilloscopes, data loggers, transient recorders, power meters and power analyzers. Based on the Rogowski principle, these probes yield very high bandwidth performance and measurement of very high currents (10A-300kA). The small coil profile (typically 8mm dia), means the coil can be retrospectively installed without disruption to an active power system. As standard, the coil is insulated at 10kVrms, insulation can be increased if required. Models are available with a variety of clip-around coil sizes to suit most conductors, allowing easy current monitoring even where access is limited. |
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Bandwidth 1Hz to 16 MHz (see bandwidth spec for each model)
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CWT LF models available with extended LF bandwidth <1Hz
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1Hz to 1MHz models available (IRF range)
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Models covering a 10A - 300,000Amps range
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0.2% accuracy
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10kV Insulation capability
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Flexible "clip-around" coil
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±6V Instantaneous isolated output ideal for scopes, data loggers, PCI DAC cards and power analyzers
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Uses 4 x AA batteries or 12V ac adapter (110V or 230Vac)
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Traceable calibration certificate included
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CE marked |
Get CWT pdf data sheet
Get CWT LF (Low frequency version) pdf data sheet
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Application |
Typical uses |
| Power analyzers |
Inexpensive method of extending the current, power and harmonic measurement range without bandwidth degradation |
| Motor drives and power electronic convertors |
Allows measurement of gate turn on / turn off times and peak current |
| Motors and generator |
Easy retrospective installation of probes around conductors where regular clamp and split core CTs are unsuitable |
| Induction heating |
Measurement of high current / high frequency signals, including high order harmonic effects |
| Pulsed power applications |
Semiconductor switches, capacitor discharge and circuit breaker interruption currents |
Selection table for CWT range
| CWT Specifications |
| Type |
Sensitivity
(mV/A) |
Peak current
(kA) |
Peak di/dt
(kA/ mS)
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Noise max*1
(mV pk-pk) |
Droop
typ.
(%/ ms) |
LF (3dB) bandwidth typ. (Hz) fL |
Phase lead at 50Hz
typ. (deg) |
HF (3dB) bandwidth typ. (MHz) fH *2 |
| Coil Length
300mm |
Coil Length
700mm |
| High Sensitivity Ranges of CWT .... measuring currents from 300mA |
| CWT015 |
200.0 |
0.03 |
0.2 |
6.5 |
130 |
150 |
2.0@6kHz |
6.0 |
5.5 |
| CWT03 |
100.0 |
0.06 |
0.4 |
4.5 |
90 |
105 |
2.0@4kHz |
8.5 |
7.5 |
| CWT06 |
50.0 |
0.12 |
0.8 |
3.0 |
70 |
80 |
2.0@3kHz |
12 |
8.5 |
| CWT1 |
20.0 |
0.3 |
2.0 |
2.5 |
40 |
50 |
1.9@2kHz |
16 |
10 |
| CWT1N |
20.0 |
0.3 |
2.0 |
2.0 |
20 |
25 |
1.9@1kHz |
10 |
5 |
| CWT3 |
10.0 |
0.6 |
4.0 |
8.0 |
3.0 |
3.5 |
1.0@300Hz |
16 |
10 |
| Standard Ranges of CWT .... measuring currents from 15A |
| CWT3N |
10.0 |
0.6 |
4.0 |
14.0 |
0.9 |
1.0 |
1.7 |
10 |
5 |
| CWT6 |
5.0 |
1.2 |
8.0 |
14.0 |
0.9 |
1.0 |
1.7 |
16 |
10 |
| CWT15 |
2.0 |
3.0 |
20.0 |
7.0 |
0.7 |
0.8 |
1.3 |
16 |
10 |
| CWT30 |
1.0 |
6.0 |
40.0 |
5.0 |
0.5 |
0.6 |
0.9 |
16 |
10 |
| CWT60 |
0.5 |
12.0 |
40.0 |
3.5 |
0.35 |
0.4 |
0.6 |
16 |
10 |
| CWT150 |
0.2 |
30.0 |
40.0 |
3.0 |
0.2 |
0.2 |
0.3 |
16 |
10 |
| CWT300 |
0.1 |
60.0 |
40.0 |
3.0 |
0.1 |
0.1 |
0.2 |
16 |
10 |
| CWT600 |
0.05 |
120.0 |
40.0 |
3.0 |
0.06 |
0.05 |
0.1 |
16 |
10 |
| CWT1500 |
0.02 |
300.0 |
40.0 |
3.0 |
0.035 |
0.03 |
0.06 |
16 |
10 |
*1. Distributed around the fL (3dB) bandwidth. Additional 50/60Hz noise of approximately 2mVpk-pk applies with AC 115V and 230V supplied CWT
*2. The 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 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 015, 03, 06
CWT 1N / 3N
all other CWT’s |
PEAK 40.0
PEAK 20.0
PEAK 40.0 |
RMS 0.9 @ 70oC
RMS 1.0 @ 70oC
RMS 1.5 @ 70 oC (further information available on request) |
| Coil and cable |
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| COIL CIRCUMFERENCE ‘A’ (mm) |
300, 500, 700 or 1000mm |
| COIL CROSS SECTION ‘B’ (mm)
(dependent on "Peak coil voltage isolation" see below) |
8.5 (10kV insulation)
14.0 (with protection sleeve)
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| 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 (oC) |
-20 to 100 |
| For de-rating due to temperature cycling please consult Powertek |
| CABLE LENGTH (metre) (from box to coil) |
2.5 or 4 |
| Power input - mechanical - environmental |
| POWER SUPPLY |
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All CWT units are supplied with four AA batteries (typical life 90 hours) and a 12V-24Vdc input socket
A Power adapter is included with the CWT probe, specify 230Vac or 115Vac.
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) |
| TEMPERATURE RANGE (oC) |
0oC to +40oC |
| Ordering |
Type + ac adapter
CWT unit is supplied with 12-24Vdc input as standard + 4 AA batteries and ac adapter, specify 115Vac or 230Vac |
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Cable length |
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Coil circumference |
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Insulation |
e.g. order code =
6kApk, 4 AA Batteries, 12-24Vdc input, 115V ac adapter, 2.5 metre cable, 500mm coil and 10kV |
CWT30 -B115 |
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2.5 |
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500 |
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10 |
e.g. order code =
6kApk, 4 AA Batteries, 12-24Vdc input, 230V ac adapter, 4 metre cable, 300mm coil and 10kV |
CWT30 -B230 |
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4 |
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300 |
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10 |
e.g. order code =
1.2kApk, 4 AA rechargeable batteries, internal battery charger, 12-24Vdc input, 115V ac adapter, 2.5 metre cable, 500mm coil and 10kV |
CWT6 -R115 |
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2.5 |
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500 |
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10 | |
