CWT Mini, Rogowski, Rogowski Coil, Rogowski sensor, Powertek

The CWT Miniature current probes utilize a 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 20MHz, the CWT miniature Rogowski coil is ideal for measuring switching transients or pulsed currents starting at 300mA up to 300kA in power electronic equipment. The CWT miniature Rogowski probe is a clip around flexible coil current probe based on the Rogowski principle to achieve high bandwidth measurement and faithful conversion of 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 Rogowski Coil

The CWT miniature 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 parts of the circuit.

Full specifications for the CWT Miniature Rogowski coil range are available in CWTmini datasheet pdf

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 17MHz
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 3.5mm for 2kV isolation and 4.5mm for 5kV isolation
    Peak voltage isolation either 2kV or 5kV
Cable length - The cable connecting the cable to the integrator box comes in lengths from 1m to 4m.
Integrator power supply
    Either Battery 4 AA 1.5V standard alkali batteries typical life 70hrs
    plus- 2.1mm/2.5mm socket for 12 to 24V DC input (batteries inoperative when DC supply present)
    or Rechargeable NiMH Batteries typical life 30hrs
    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 Euro_adapter.pdf, UK_adapter.pdf and USA_adapter.pdf.
CE marked

CWT Mini Rogowski Coil 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) f_L	Phase lead at 50Hz typ. (deg)	HF (3dB) bandwidth typ. (MHz) f_H *²
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) f_L	Phase lead at 50Hz typ. (deg)	^{Coil Length} ^100mm	^{Coil Length} ^200mm
High Sensitivity Ranges of CWT .... measuring currents from 300mA
CWT015	200.0	0.03	0.2	6.5	130	150	2.0@6kHz	5.0	3.5
CWT03	100.0	0.06	0.4	4.5	90	105	2.0@4kHz	8.5	5.5
CWT06	50.0	0.12	0.8	3.0	70	80	2.0@3kHz	17	12
CWT1	20.0	0.3	2.0	2.5	40	50	1.9@2kHz	17	12
CWT3	10.0	0.6	4.0	8.0	3.0	3.5	1.0@300Hz	17	12
Standard Ranges of CWT .... measuring currents from 15A
CWT6	5.0	1.2	8.0	14.0	0.9	1.0	1.7	17	12
CWT15	2.0	3.0	20.0	7.0	0.7	0.8	1.3	17	12
CWT30	1.0	6.0	25.0	5.0	0.5	0.6	0.9	17	12
CWT60	0.5	12.0	25.0	3.5	0.35	0.4	0.6	17	12
CWT150	0.2	30.0	25.0	3.0	0.2	0.2	0.3	17	12
CWT300	0.1	60.0	25.0	3.0	0.1	0.1	0.2	17	12
CWT600	0.05	120.0	25.0	3.0	0.06	0.05	0.1	17	12
CWT1500	0.02	300.0	25.0	3.0	0.035	0.03	0.06	17	12

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)

CWT 015, 03, 06
CWT 1N

all other CWT’s

PEAK 25.0

RMS 0.6 @ 70^oC

RMS 1.0 @ 70^oC

RMS 1.2 @ 70 ^oC (further information available on request)

Coil and cable
COIL CIRCUMFERENCE ‘A’ (mm)	100 or 200mm optional lengths to 1000mm
COIL CROSS SECTION ‘B’ (mm)	3.5mm for 2kV isolation 4.5mm for 5kV isolation
PEAK COIL VOLTAGE ISOLATION (kV)	2 or 5kV
Safe peak working voltage to earth. 2kV coils are flash tested at 3.8kV/60Hz for 60 seconds and 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 (^oC)	-20^oC to 100^oC
For de-rating due to temperature cycling please consult Powertek
CABLE LENGTH (metres) (from box to coil)	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 (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)	0^oC to 40 ^oC

Ordering	Model CWT mini unit is supplied with bnc-bnc cable, 12-24Vdc input, 4 AA batteries, power adapter, user manual, calibration certificate and carry case.	/	Power Option B-Battery R-Rechargeable	/	Cable length (m)	/	Coil circumference (mm)	/	Insulation (kV)
e.g. order code 30Apk, 4 AA Batteries, ac adapter, 12-24Vdc input, 1metre cable, 100mm coil, 5kV insulation	CWT mini 015	/	B	/	1	/	100	/	5
e.g. order code 6kApk, 4 AA Batteries, ac adapter, 12-24Vdc input, 2.5 metre cable, 200mm coil, 2kV insulation	CWT mini 30	/	B	/	2.5	/	200	/	2
e.g. order code 120Apk, 4 x AA rechargeable Batteries, internal battery charger, ac adapter, 12-24Vdc input, 2.5metre cable, 100mm coil length and 5kV isolation	CWT mini 06	/	R	/	2.5	/	100	/	5