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CWT LF
Wideband current probes |
Powertek |
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The
CWT LF current sensors are
rugged clip around flexible coil
wideband 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 - ideally suited for power electronic applications. Based on the Rogowski principle, these probes
have intrinsic high
bandwidth performance 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 variety of
clip-around coil sizes to suit most conductors, allowing easy current monitoring even
where access is limited. |
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CWT LF (low freq) datasheet | CWT application notes | CWT Calibration
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Application |
Typical uses |
| Power analyzers | Convenient method of extending the current, power and harmonic measurement range without bandwidth degradation. Excellent low frequency (0.5Hz) performance along with low phase shift |
| Motor drives and power electronic converters | Allows measurement of IGBT switching times, 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 current applications | Semiconductor switches: IGBT, Power MOSfets, capacitor discharge and circuit breaker interruption currents |
| Capacitor discharge and lightning strike research | Measurement of peak currents without breaking conductors |
Selection table for CWT range
| CWT Specifications | |||||||||
| Type |
Sensitivity (mV/A) |
Peak
current (kA) |
Peak
di/dt (kA/uS) |
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 | |
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Coil Length 300mm |
Coil Length 700mm |
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| Standard Coils | |||||||||
| CWT03LF | 100.0 | 0.06 | 0.4 | 15.0 | 4.6 | 5.1 | 8.3 | 6.5 | 3.0 |
| CWT06LF | 50.0 | 0.12 | 0.8 | 15.0 | 2.3 | 2.6 | 4.2 | 6.5 | 3.0 |
| CWT1LF | 20.0 | 0.3 | 2.0 | 15.0 | 1.0 | 1.0 | 1.8 | 6.5 | 3.0 |
| CWT3LF | 10.0 | 0.6 | 4.0 | 15.0 | 0.5 | 0.55 | 0.85 | 6.5 | 3.0 |
| CWT6LF | 5.0 | 1.2 | 8.0 | 15.0 | 0.25 | 0.27 | 0.45 | 6.5 | 3.0 |
| CWT15LF | 2.0 | 3.0 | 11.0 | 15.0 | 0.1 | 0.11 | 0.18 | 6.5 | 3.0 |
| CWT30LF | 1.0 | 6.0 | 11.0 | 15.0 | 0.05 | 0.055 | 0.09 | 6.5 | 3.0 |
| CWT60LF | 0.5 | 12.0 | 11.0 | 15.0 | 0.025 | 0.022 | 0.045 | 6.5 | 3.0 |
| CWT150LF | 0.2 | 30.0 | 11.0 | 15.0 | 0.01 | 0.011 | 0.018 | 6.5 | 3.0 |
| CWT300LF | 0.1 | 60.0 | 11.0 | 10.0 | 0.007 | 0.008 | 0.012 | 6.5 | 3.0 |
| CWT600LF | 0.05 | 120.0 | 11.0 | 5.0 | 0.007 | 0.008 | 0.012 | 6.5 | 3.0 |
| CWT1500LF | 0.02 | 300.0 | 11.0 | 4.0 | 0.007 | 0.008 | 0.012 | 10.0 | 5.0 |
| Miniature Coils |
Coil Length 100mm |
Coil Length 200mm |
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| CWT03LF | 100.0 | 0.06 | 0.4 | 16.0 | 10.2 | 11.0 | 18.6 | 5.0 | 4.0 |
| CWT06LF | 50.0 | 0.12 | 0.8 | 16.0 | 5.1 | 5.6 | 9.3 | 12.0 | 7.5 |
| CWT1LF | 20.0 | 0.3 | 2.0 | 15.0 | 2.2 | 2.3 | 4.0 | 12.0 | 7.5 |
| CWT3LF | 10.0 | 0.6 | 4.0 | 15.0 | 1.0 | 1.1 | 1.7 | 12.0 | 7.5 |
| CWT6LF | 5.0 | 1.2 | 8.0 | 15.0 | 0.5 | 0.55 | 0.85 | 12.0 | 7.5 |
| CWT15LF | 2.0 | 3.0 | 14.0 | 15.0 | 0.2 | 0.22 | 0.35 | 12.0 | 7.5 |
| CWT30LF | 1.0 | 6.0 | 14.0 | 15.0 | 0.1 | 0.11 | 0.18 | 12.0 | 7.5 |
| CWT60LF | 0.5 | 12.0 | 14.0 | 15.0 | 0.05 | 0.055 | 0.09 | 12.0 | 7.5 |
| CWT150LF | 0.2 | 30.0 | 14.0 | 15.0 | 0.02 | 0.022 | 0.035 | 12.0 | 7.5 |
| CWT300LF | 0.1 | 60.0 | 14.0 | 15.0 | 0.01 | 0.011 | 0.018 | 12.0 | 7.5 |
| CWT600LF | 0.05 | 120.0 | 14.0 | 10.0 | 0.007 | 0.008 | 0.012 | 12.0 | 7.5 |
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*1. Distributed around the fL
(3dB) bandwidth *2. For 2.5m cable length. Contact Powertek for values of fH for other coil and cable lengths |
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TYPICAL ACCURACY (full scale) |
Traceable calibration to
±0.2% with condcutor centrail in the
lop Variation with conductor position in the coil loop typically ±1% for standard coils Variation with conductor in position in the coil loop typically ±2% for miniature coils |
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| TYPICAL LINEARITY | ±0.05% (full scale) | ||
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ABSOLUTE MAXIMUM
VALUES OF di / dt (kA/µs) (value must not be exceeded) |
(Standard Coil) (Minaiture Coil) |
PEAK
11.0 PEAK 14.0 |
RMS 0.8
@ 70oC
RMS 0.85 @ 70oC(further information available on request) |
| Coil and cable |
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| COIL CIRCUMFERENCE ‘A’ (mm) | 300, 500, 700 or 1000mm | |
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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)
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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 | |
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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 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 (oC) | 0oC to +40oC |
| Ordering |
Model |
/ | 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) |
CWT30LF B | / | 2.5 |
/ | 500 |
| e.g. order code = 6kApk, 4 AA Batteries, 12-24Vdc input, 230V ac adapter, 4 metre cable, 300mm coil |
CWT30LF B | / | 4 |
/ | 300 |
| e.g. order code = 1.2kApk, 4 AA rechargeable batteries, internal battery charger, 12-24Vdc input, ac adapter, 2.5 metre cable, 700mm coil |
CWT6LF R | / | 2.5 |
/ | 700 |
All
CWT LF 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.
Links:
CWT LF (low freq) datasheet |
CWT application notes |
CWT Calibration
