ARU series
Ref: ARU-B100-D125, ARU-B100-D175, ARU-B100-D250, ARU-B100-D300
Outdoor flexible clip-around Rogowski coil for the electronic measurement of AC current with
galvanic separation between the primary circuit (power) and the secondary circuit (measurement).
The patented Perfect Loop Technology dramatically reduces both the error due to the positionof the measured conductor within the aperture, and the error due to the proximity of external
conductors.With a ruggedized design, ARU is adapted to difficult environments such as outdoor
usages or underground medium voltage distribution stations.

Features

Applications● Designed for outdoor use(UV, water, dust and ice standards)● Outdoor substations● High sensitivity 100 mV/kA @ 50 Hz● Flexible circular shape● Rated insulation CAT III 1000 V PD2, CAT IV 600 V PD3Class 0.5 (IEC 61869-10)● Protection degree IPX8

● ⌀ 125, 175, 250 and 300 mm sensing aperture● TA = −40 ... +80 °C● An innovative patented clasp drastically reduces the
positioning error near the closing● Internal shield for enhanced measurement accuracy at low
primary currents.

● Distribution transformer monitoring● Medium voltage isolated cable distribution● Underground substations● Pole-mounted transformers● Low voltage overhead lines● Distributions system equipment.

Standards● IEC 61010-1:2010/AMD1: 2016; IEC 61010-2-32: 2012
● IEC 61869-10: 2017
● UL: 61010-1: 2012.

Advantages

Application Domains● Ruggedized design adapted to outdoor or undergroundenvironment without need of additional protection● Smart Grid.

● Industrial● Very low positioning error● Very good accuracy● Does not saturate with overcurrent and short circuits
currents● Fast and easy installation.

97.R8.99.000.0, 97.R8.99.003.0, 97.R8.99.004.0, 97.R8.99.006.0, 97.R9.99.000.0, 97.R9.99.003.0, 97.R9.99.004.0, 97.R9.99.006.0, 97.T2.99.000.0, 97.T2.99.003.0, 97.T2.99.004.0,
97.T2.99.006.0, 97.T3.99.000.0, 97.T3.99.003.0, 97.T3.99.004.0, 97.T3.99.006.0
Page 1/11
		
LEM International SA
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Route du Nant-d’Avril, 152
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ARU series
Safety⚠

CautionIf the device is used in a way that is not specified by the manufacturer, the protection provided by the device may be compromised.
Always inspect the current sensor unit and connecting cable before using this product and do not use it if damaged .
Mounting assembly shall guarantee the maximum primary busbar temperature, fulfill clearance and creepage distance, minimize
electric and magnetic coupling, and unless otherwise specified can be mounted in any orientation.

Caution, risk of electrical shock
This current sensor must be used in electric/electronic equipment with respect to applicable standards and safety requirements inaccordance with the manufacturer’s operating specifications.
This current sensor is intended for use in an electrical installation with restricted access.
Therefore, in normal operation, it is not accessible. For installation or in maintenance phases, it is accessible only to qualified
person.
It is intended to be connected onto SELV equipment input, of up to 30 V RMS.
When operating, certain parts of the current sensor can carry hazardous voltages (e.g. primary busbar, power supply).
De-energize all circuits and hazardous live parts before installing the product.
All installations, maintenance, servicing operations and use must be carried out by trained and qualified personnel practicing
applicable safety precautions.
If the current sensor is used in a manner not specified by the manufacturer, the protection provided by the equipment may be
impaired.
Ignoring this warning can lead to injury and/or cause serious damage.
This current sensor is a build-in device, whose hazardous live parts must be inaccessible after installation.
This current sensor must be mounted in a suitable end-enclosure.
Use caution during installation, use and uninstalling of this product; high voltages and currents, high temperature (above 70 °C)
may be present inside the electrical equipment.
Use personal protective equipment (clothes, gloves, ...).
This current sensor is a built-in device, not intended to be cleaned with any product. Nevertheless if the user must implement
cleaning or washing process, validation of the cleaning program has to be done by himself.
Do not dispose of this product as unsorted municipal waste. Contact a qualified recycler for disposal.

Caution! Risk of electrical shock
Do not apply around or remove from uninsulated hazardous live conductors which may result in electric shock, electric burn or
arc flash.

Equipment protected throughout by double insulation or reinforced insulation (when properly clipped and locked).

		
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ARU series
Absolute maximum ratings
Parameter

Symbol

Unit

Value

Maximum secondary voltage (RMS)

US max

V

30

Maximum primary conductor temperature

TB max°C

105

Stresses above these ratings may cause permanent damage.
Exposure to absolute maximum ratings for extended periods may degrade reliability.

UL 61010-1: Ratings and assumptions of certification
File # E330077 Volume D2.

Standards● UL 61010-1, 3rd Edition, May 11, 2012, Revised April 29 2016
● CAN/CSA-C22.2 No. 61010-1-12, 3rd Edition, Revision dated April 29 2016.

Additional standards● IEC 61010-2-032: 2012 (Third Edition)● UL 61010-2-032 (IEC 61010-2-032:2012)● CAN/CSA-C22.2 NO. 61010-2-032:14

RatingPower supply not required.
Measurement rating: 1000 V AC CAT III and 600 V AC CAT IV, 50/60 Hz
30 V max on output (at 100 mV/1kA)

Engineering conditions of acceptability
For use only in or with complete equipment where the acceptability of the combination is determined by UL LLC.
When installed in an end-product, consideration must be given to the following:- ARU series has been investigated as Type B current sensors according IEC 61010-2-032 3rd ed.
- This series is considered as Open Device in the meaning of UL 61010-1, and it is intended to be installed in Industrial Control
Equipment, where a suitable enclosure shall be provided in the end-use application.
- The current sensors are intended for use in an electrical installation with restricted access. Therefore, in normal operation, they
are not accessible. The current sensors are accessible only to skilled technicians for installation and maintenance purposes only.
- The current sensors have been evaluated for overvoltage category III (up to 1000 V AC) under Pollution Degree 2, or for
overvoltage category IV (up to 600 V AC) under Pollution Degree 3.
-T he current sensors have been evaluated for maximum output voltage 30 V (at 100 mV / 1 kA sensitivity).
- Reinforced insulation between internal circuits or output wiring, and external surface of the enclosure (that can be in contact withhazardous voltage of the circuits under measurement) can be guaranteed only when the sleeve is connected to case (i.e. in thecondition of closed loop); no reinforced insulation is guaranteed by the sleeve when not connected to the enclosure.
For ARU series the need for the following shall be considered in the end-product:-M arkings and documentation that comply with Clause 5.
-T he following tests shall be performed in the end-product evaluation: Dielectric Strength-T he unit is considered acceptable for use in 80 °C maximum surrounding air temperature- A suitable enclosure shall be provided in the end-use application-T he terminals have not been evaluated for field wiring-P rimary conductor or busbar temperature should never exceed 105 °C- The current sensor is suitable for installations in dry and damp location, but it is not suitable for installations in wet locations as
defined in the ANSI/NFPA 70 National Electrical Code (NEC) and the Canadian Electrical Code, Part 1 (CE Code, Part 1)-B ased on −40 °C to 80 °C temperature range and pollution degree 3 up to 600 V, the current sensor can be installed in
uncontrolled environment such as outdoor installation protected against weather, water and direct sunlight.

		
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ARU series
Insulation coordination
Parameter

SymbolUnit≤ Value

RMS voltage for AC insulation test, 50 Hz, 1 min

Ud

kV

7.4

According to IEC 61010-1

Impulse withstand voltage 1.2/50 μs

UNi

kV

12.8

According to IEC 61010-1

Partial discharge RMS test voltage (qm < 10 pC)

Ut

V

1275

According to IEC 60664-1

Clearance (pri. - sec.)

dCI

mm

> 16

Shortest distance through air

Creepage distance (pri. - sec.)

dCp

mm

> 16

Shortest path along device body

Case material

-

-

V0

According to UL 94

Comparative tracking index

CTI

Comment

600

Application example - indoor use
RMS voltage line-to-neutral

V

1000

Reinforced insulationaccording to IEC 61010-1
CAT III 1), PD2

Application example - outdoor use
RMS voltage line-to-neutralV

600

Reinforced insulationaccording to IEC 61010-1
CAT IV 2), PD3

Environmental and mechanical characteristics
Parameter

SymbolUnit

Min

Ambient operating temperature

TA

°C

−40

80

Ambient storage temperature

TA st

°C

−40

80

Relative humidity (non-condensing)

RH

%

0

90

Altitude above sea level
Mass ⌀ 125
Mass ⌀ 175
Mass ⌀ 250
Mass ⌀ 300
Notes:

1)
2)

Typ

m

Max

Comment

2000

m

g

236

Cable length: 1.5 m

m

g

247

Cable length: 1.5 m

m

g

277

Cable length: 1.5 m

m

g

297

Cable length: 1.5 m

OVERVOLTAGE CATEGORY lll is for equipment intended to form part of a building wiring installation.
OVERVOLTAGE CATEGORY lV is for equipment installed at or near the origin of the electrical supply to a building,between the building entrance and the main distribution board.

		
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ARU series
Electrical data ARU-B100-D125
At TA = 25 °C, RL = 10 kΩ, unless otherwise noted.

Parameter

SymbolUnit

Rated primary current

IPrA

Rated short-time thermal current

Ith

kA

20

@ 50 Hz

Rated transformation ratio

kr

kA/V

10

@ 50 Hz

Rated frequency

fr

Hz

50/60

Secondary voltage

US

mV

100
120

Mutual inductance

M

nH

321.9

Temperature coefficient of M

TCM

ppm/k

±30

Frequency bandwidth (+3 dB)
resonance(−3 dB)

BW

kHz

162
322
519

2)

Phase displacement 3) @ 50/60 Hz

Δφ

°

0.007

2)

Coil inductance

LS

µH

1080

Coil resistance

RS

Ω

113

Ratio error (centered)

ε

%

−0.5

0.5

Ratio error (all positions)

ε

%

−1

1

4)

Linearity error

εL%Error due to magnetic field of external conductor
current

εI ext

%

±0.65

5)

Notes:

Min

Typ

Max

Comment
Not applicable 1)@ 50 Hz, IP = 1 kA
@ 60 Hz, IP = 1 kA

Cable length: 1.5 m

Class 0.5 accuracy
according to IEC 61869-10

None
0

±0.4

The Rogowski coil can measure any primary current as there is no saturation effect.
Frequency bandwidth and phase shift modeling schematic can be provided on request.
3)
Referring to the main phase offset of 90 ° (a Rogowski coil is a derivative current transducer).
4)
Considering a primary conductor of at least ⌀18 mm, perpendicular and on contact with the Rogowski coil.
5)
Considering an external conductor of at least ⌀18 mm the same current level than internal conductor,
perpendicular and on contact with the Rogowski coil.
1)
2)

		
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ARU series
Electrical data ARU-B100-D175
At TA = 25 °C, RL = 10 kΩ, unless otherwise noted.

Parameter

SymbolUnit

Rated primary current

IPrA

Rated short-time thermal current

Ith

kA

20

@ 50 Hz

Rated transformation ratio

kr

kA/V

10

@ 50 Hz

Rated frequency

fr

Hz

50/60

Secondary voltage

US

mV

100
120

Mutual inductance

M

nH

322.4

Temperature coefficient of M

TCM

ppm/k

±30

Frequency bandwidth (+3 dB)
resonance(−3 dB)

BW

kHz

165
299
455

2)

Phase displacement 3) @ 50/60 Hz

Δφ

°

0.004

2)

Coil inductance

LS

µH

1244

Coil resistance

RS

Ω

128

Ratio error (centered)

ε

%

−0.5

0.5

Ratio error (all positions)

ε

%

−1

1

4)

Linearity error

εL%Error due to magnetic field of external conductor
current

εI ext

%

±0.65

5)

Notes:

Min

Typ

Max

Comment
Not applicable 1)@ 50 Hz, IP = 1 kA
@ 60 Hz, IP = 1 kA

Cable length: 1.5 m

Class 0.5 accuracy
according to IEC 61869-10

None
0

±0.4

The Rogowski coil can measure any primary current as there is no saturation effect.
Frequency bandwidth and phase shift modeling schematic can be provided on request.
3)
Referring to the main phase offset of 90 ° (a Rogowski coil is a derivative current transducer).
4)
Considering a primary conductor of at least ⌀18 mm, perpendicular and on contact with the Rogowski coil.
5)
Considering an external conductor of at least ⌀18 mm the same current level than internal conductor,
perpendicular and on contact with the Rogowski coil.
1)
2)

		
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ARU series
Electrical data ARU-B100-D250
At TA = 25 °C, RL = 10 kΩ, unless otherwise noted.

Parameter

SymbolUnit

Rated primary current

IPrA

Rated short-time thermal current

Ith

kA

20

@ 50 Hz

Rated transformation ratio

kr

kA/V

10

@ 50 Hz

Rated frequency

fr

Hz

50/60

Secondary voltage

US

mV

100
120

Mutual inductance

M

nH

323.9

Temperature coefficient of M

TCM

ppm/k

±30

Frequency bandwidth (+3 dB)
resonance(−3 dB)

BW

kHz

145
252
382

2)

Phase displacement 3) @ 50/60 Hz

Δφ

°

0.007

2)

Coil inductance

LS

µH

1701

Coil resistance

RS

Ω

175

Ratio error (centered)

ε

%

−0.5

0.5

Ratio error (all positions)

ε

%

−1

1

4)

Linearity error

εL%Error due to magnetic field of external conductor
current

εI ext

%

±0.65

5)

Notes:

Min

Typ

Max

Comment
Not applicable 1)@ 50 Hz, IP = 1 kA
@ 60 Hz, IP = 1 kA

Cable length: 1.5 m

Class 0.5 accuracy
according to IEC 61869-10

None
0

±0.4

The Rogowski coil can measure any primary current as there is no saturation effect.
Frequency bandwidth and phase shift modeling schematic can be provided on request.
3)
Referring to the main phase offset of 90 ° (a Rogowski coil is a derivative current transducer).
4)
Considering a primary conductor of at least ⌀18 mm, perpendicular and on contact with the Rogowski coil.
5)
Considering an external conductor of at least ⌀18 mm the same current level than internal conductor,
perpendicular and on contact with the Rogowski coil.
1)
2)

		
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ARU series
Electrical data ARU-B100-D300
At TA = 25 °C, RL = 10 kΩ, unless otherwise noted.

Parameter

SymbolUnit

Rated primary current

IPrA

Rated short-time thermal current

Ith

kA

20

@ 50 Hz

Rated transformation ratio

kr

kA/V

10

@ 50 Hz

Rated frequency

fr

Hz

50/60

Secondary voltage

US

mV

100
120

Mutual inductance

M

nH

324.9

Temperature coefficient of M

TCM

ppm/k

±30

Frequency bandwidth (+3 dB)
resonance(−3 dB)

BW

kHz

134
230
346

2)

Phase displacement 3) @ 50/60 Hz

Δφ

°

0.007

2)

Coil inductance

LS

µH

2018

Coil resistance

RS

Ω

208

Ratio error (centered)

ε

%

−0.5

0.5

Ratio error (all positions)

ε

%

−1

1

4)

Linearity error

εL%Error due to magnetic field of external conductor
current

εI ext

%

±0.65

5)

Notes:

Min

Typ

Max

Comment
Not applicable 1)@ 50 Hz, IP = 1 kA
@ 60 Hz, IP = 1 kA

Cable length: 1.5 m

Class 0.5 accuracy
according to IEC 61869-10

None
0

±0.4

The Rogowski coil can measure any primary current as there is no saturation effect.
Frequency bandwidth and phase shift modeling schematic can be provided on request.
3)
Referring to the main phase offset of 90 ° (a Rogowski coil is a derivative current transducer).
4)
Considering a primary conductor of at least ⌀18 mm, perpendicular and on contact with the Rogowski coil.
5)
Considering an external conductor of at least ⌀18 mm the same current level than internal conductor,
perpendicular and on contact with the Rogowski coil.
1)
2)

Definition of typical, minimum and maximum values
Minimum and maximum values for specified limiting and safety conditions have to be understood as such as well as values shownin “typical” graphs.
On the other hand, measured values are part of a statistical distribution that can be specified by an interval with upper and lower
limits and a probability for measured values to lie within this interval.
Unless otherwise stated (e.g. “100 % tested”), the LEM definition for such intervals designated with “min” and “max” is that theprobability for values of samples to lie in this interval is 99.73 %.
For a normal (Gaussian) distribution, this corresponds to an interval between −3 sigma and +3 sigma. If “typical” values are notobviously mean or average values, those values are defined to delimit intervals with a probability of 68.27 %, corresponding to aninterval between −sigma and +sigma for a normal distribution.
Typical, minimum and maximum values are determined during the initial characterization of the product.

		
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ARU series

ARU-B100-D125, ARU-B100-D175, ARU-B100-D300

ARU-B100-DXXXFamily:Rogowski coil

Shape:
D: circular

Output signal:
100: mV/kA

Aperture:
D125: ⌀ 125 mm
D175: ⌀ 175 mm
D250: ⌀ 250 mm
D300: ⌀ 300 mm

Other cable lengths available:
Product name

Length (m)Mass (g)ARU-B100-D125/SP3

3298

ARU-B100-D125/SP4

4.5

359

ARU-B100-D125/SP6

6421

ARU-B100-D175/SP3

3309

ARU-B100-D175/SP4

4.5

370

ARU-B100-D175/SP6

6432

ARU-B100-D250/SP3

3339

ARU-B100-D250/SP4

4.5

400

ARU-B100-D250/SP6

6462

ARU-B100-D300/SP3

3359

ARU-B100-D300/SP4

4.5

420

ARU-B100-D300/SP6

6482

Accuracy class according to IEC 61869-10
Conductor
Conductorc centeredentered

1.5
1.25
1

Currente
rror (%)
Current error
(%)

0.75
0.5

Class 0.5

0.25
0
-0.25
-0.5
-0.75
-1
-1.25
-1.5

55%
% IIPrPr

20% IIPr20%

Pr

100 %IIPr
100%
Pr

120 % IIPr
120%
Pr

KKPcr xxIPr
IPr
Pcr

Accuracy class limit of IEC 61869-10
Accuracy class limit of ARU-B100 Rogowski
		
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ARU series

Terms and definitions
Rated transformation ratio kr
Ratio of kr to the actual secondary voltage.

Ratio error ε
The current ratio error, expressed as a percentage, is definedby the formula:ε=kr US − IP
IP

× 100 %

Where:
kr: is the rated transformation ratio
IP: is the actual primary current
US: is the actual secondary voltage when IP is flowing

Phase displacement ∆φ
The Δφ is the difference in phase between the primary current
and the ideal secondary voltage phasors. The direction of
the phasors being that the angle is 90 ° (leading) for an ideal
Rogowski coil.
The phase displacement is said to be positive when thesecondary voltage phasor leads the primary current phasor.

Linearity error εL
The linearity error εL is the maximum positive or negative
difference between the measured points and the linear
regression line, expressed as a percentage of IPr.

Rated short-time thermal current Ith
Maximum value of the primary current which the Rogowski willwithstand for a specified short time without suffering harmful
effects.

		
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ARU series
Dimensions (in mm)

ARU LOOP

Connection
diPdt
IP

US+
US-

Mechanical characteristics● General tolerance● Output cable length● Termination● Cable tie maximum effort±1 mm
See table page 10
or drawing above
2 stripped wires
0.5 mm2 (AWG 20)
50 N

Remarks● US = US+ - US- is positive when an increasing primary
current di/dt flows in the direction of the arrow.
● Due to low positioning error (εPOS), the device does notneed to be physically fastened around the primaryconductor. Should the device be secured, make sure nomechanical stress is applied to the coil itself.
● This product is not intended for outdoor use.
● Installation of the sensor must be done unless otherwise
specified on the datasheet, according to LEM Sensor
Generic Mounting Rules. Please refer to LEM document
N°ANE120504 available on our Web site:
https://www.lem.com/en/file/3137/download/.
		
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