Current Transducer LWSR 250-P

IP N = 250 A

For the electronic measurement of currents: DC, AC, pulsed..., with galvanic separation between
the primary and the secondary circuit.

Features

Standards● Closed loop multi-range current transducer● IEC 62109-1: 2010

● Voltage output● IEC 61800-5-1: 2007

● Unipolar supply voltage.

● IEC 62477-1: 2012
● IEC 61000-6-2: 2016

Advantages● IEC 61000-6-3: 2006+A1/2010● Very low offset drift● IEC 61800-3: 2017

● Very good du/dt immunity.

● UL 508: 2018.

Applications

Application Domain● Solar inverters● Industrial.

● AC variable speed and servo motor drives● Battery supplied applications● Uninterruptible Power Supplies (UPS)● Switched Mode Power Supplies (SMPS)● Power supplies for welding applications.

N° 52.E2.45.000.0
25May2023/Version 2

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LWSR 250-P
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 electronics 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 transducer must be used in limited-energy secondary circuits SELV according to IEC 61800-5-1, in electric/electronic equipmentwith respect to applicable standards and safety requirements in accordance with the manufacturer’s operating specifications.
When operating the transducer, certain parts of the module can carry hazardous voltage (e.g. primary busbar, power supply).
All installations, maintenance, servicing operations and use must be carried out by trained and qualified personnel practicing
applicable safety precautions.
If the transducer 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 transducer is a build-in device, whose hazardous live parts must be inaccessible after installation.
This transducer must be mounted in a suitable end-enclosure.
Use caution during installation and use of this product; high voltages and currents may be present in circuit under test.
This transducer 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.

ESD susceptibility
The product is susceptible to be damaged from an ESD event and the personnel should be grounded when handling it.
Do not dispose of this product as unsorted municipal waste. Contact a qualified recycler for disposal.
Although LEM applies utmost care to facilitate compliance of end products with applicable regulations during LEM productdesign, use of this part may need additional measures on the application side for compliance with regulations regarding EMC andprotection against electric shock. Therefore LEM cannot be held liable for any potential hazards, damages, injuries or loss of life
resulting from the use of this product.

Underwriters Laboratory Inc. recognized component

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LWSR 250-P
Absolute maximum ratings
Parameter

Symbol

Unit

Value

Maximum supply voltage

UC maxV

7

Maximum primary conductor temperature

TB max°C

110

Maximum primary current

IP maxA

10 × IP N

UESD HBM

kV

4Electrostatic discharge voltage(HBM - Human Body Model)

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

UL 508: Ratings and assumptions of certification
File # E189713 Volume: 2 Section: 20
Standards● CSA C22.2 NO. 14-10 INDUSTRIAL CONTROL EQUIPMENT - Edition 11● UL 508 STANDARD FOR INDUSTRIAL CONTROL EQUIPMENT - Edition 17
Ratings
Parameter

SymbolPrimary involved potential

Unit

Value

V AC/DC1000

Max surrounding air temperature

TA

°C

105

Primary current

IP

A

250

Transducer supply

UC

V DC

5

Output voltage

Uout

V DC

0 to 5

Conditions of acceptability
When installed in the end-use equipment, consideration shall be given to the following:
1 - The secondary circuit pin terminals have not been evaluated for field wiring.
2 - Low voltage control circuit shall be supplied by an isolating 5 V DC supply source.
3 - The product is to be mounted on a printed wiring board.
4 - The product shall be connected at the secondary side of a UL certified surge protective device which has been evaluated with
the Standard for Transient Voltage Surge Suppressors, UL 1449 with a maximum clamping voltage of 8 kV.
Marking
Only those products bearing the UL or UR Mark should be considered to be Listed or Recognized and covered under UL’s
Follow-Up Service. Always look for the Mark on the product.

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LWSR 250-P
Insulation coordination
Parameter

Symbol

Unit

Value

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

Ud

kV

4.3

According to IEC 60664-1

Impulse withstand voltage 1.2/50 µs

UNi

kV

8

According to IEC 60664-1

Partial discharge RMS test voltage (qm < 10 pC)

Ut

V

1500

According to IEC 60664-1

Comparative tracking index

CTI

V

600

Case material

-

-

V0

According to UL 94

Clearance (pri. - sec.)

dCI

mm

> 14

Shortest distance through air

Creepage distance (pri. - sec.)

dCp

mm

> 14

Shortest path along device body

Application example
System voltage RMS

V

600

Reinforced insulation according toIEC 61800-5-1, IEC 62109-1
CAT III, PD2

Application example
System voltage RMS

V

1000

Basic insulation according toIEC 61800-5-1, IEC 62109-1
CAT III, PD2

Application example
System voltage DC

V

1000

Reinforced insulation according toIEC 61800-5-1, IEC 62109-1
CAT II, PD2

Comment

Environmental and mechanical characteristics
Parameter

SymbolUnit

Min

Ambient operating temperature

TA

°C

−40

105

Ambient storage temperature

TA st

°C

−55

125

Mass

m

g

Note:

1)

Typ

Max

Comment

1)

76

85 °C and 5 % RH to 95 % RH is applied in LVD certification.

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LWSR 250-P
Electrical data
At TA = 25 °C, UC = +5 V, NP = 1 turn, RL = 10 kΩ internal reference unless otherwise noted (see Min, Max, typ. definition paragraph in page 6).
Lines with a * in the comment column apply over the −40 … 105 °C ambient temperature range.

ParameterMax

Comment

Unit

Primary nominal RMS current

IP N

A

Primary current, measuring range

IP M

A

−380

380

−40 °C ~ +95 °C

Maximum measured peak overcurrent(transformer effect)ÎP meas

A

−650

650

di/dt = 50 A/µs,during timeat 650 A is 1000 µs

Supply voltage

UC

V

4.75

Current consumption

IC

mA

Reference voltage @ IP = 0 A

Uref

V

Output voltage @ IP = 0 A

Uout

V

Electrical offset voltage

UO E

mV

Electrical offset current referred to primary

IO E

mA

TCIO E

ppm/K

−10

10

*

TCUref

ppm/K

−100

100

*

Temperature coefficient of IO E

1)

Temperature coefficient of Uref

Min

Typ

Symbolsee “Maximum continuous
DC primary current ” onpage 6

250

5

5.25

I (mA)
18 + PNS

I (mA)
20.5 + P
NS

NS = 1600 turns

2.5

2.515

Internal reference

−1.57

1.57

100 % tested Uout − Uref

−500

500

100 % tested

2.485

*

Uref

Internal reference

Nominal sensitivity

SN

mV/A

Sensitivity errorεS% of IP N

Temperature coefficient of S

TCS

ppm/K

−60

60

Linearity errorεL% of IP N

−0.15

0.15

Magnetic offset current (5 × IP N)
referred to primary

IO M

mA

−200

200

Peak-to-peak noise voltage
DC … 10 kHz
DC … 100 kHz
DC … 1 MHz

Uno ppmVpp

Delay time to 10 % of the final output value
for IP N step

tD 10

µs

1

di/dt = 50 A/µs

Delay time to 90 % of the final output value
for IP N step

tD 90

µs

2

di/dt = 50 A/µs

Frequency bandwidth (±3 dB)

BW

kHz

200

Total error

εtot% of IP N−1

1

Total error @ TA = 85 °C

εtot 85% of IP N

−1.4

1.4

Sum of sensitivity and linearity errorεS L% of IP N

−0.83

0.83

Sum of sensitivity and linearity error
at 85° C

εS L 85% of IP N

−1.2

1.2

Notes:

0.8

100 % tested
*

0.57
1.85
2.55

1)

PPM refers to full-scale which corresponds to a primary nominal RMS current

2)

Total error  tot (TA ) =  tot 25 +3)

Sum of sensitivity and linearity error  S L (TA ) =  S L 25 +TCS  TCI O E
x TA -25
10000

781.25 mV/IP N

3.125
−0.8

small signal
See formula note 2)

See formula note 3)

TCS  TCI O E
x TA -25 .
10000

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LWSR 250-P
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, maximal and minimal values are determined during the initial characterization of the product.

Maximum continuous DC primary current
320

Uc=5.25V
Uc=5V
Uc=4.75V

300

IIpP (A)

280
260
250
240
220
200
180
160

-40

-25

-10

5

20

35

T A (℃)

50

65

75

80

95

105
110

The maximum continuous DC primary current plot shows the boundary of the area for which all the following conditions are true:● IP < IP M
● Junction temperature TJ < 150 °C● Primary conductor temperature < 110 °C

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LWSR 250-P
Terms and definitions
Ampere-turns and amperes

Sensitivity and linearity

The transducer is sensitive to the primary current linkage ΘP(also called ampere-turns).
ΘP = NP · IP
Where NP is the number of primary turn (depending on theconnection of the primary jumpers).
Caution: As most applications will use the transducer with only
one single primary turn (NP = 1), much of this datasheet iswritten in terms of primary current instead of current linkages.
However, the ampere-turns (A) unit is used to emphasis thatcurrent linkages are intended and applicable.

To measure sensitivity and linearity, the primary current (DC) is
cycled from 0 to IP, then to −IP and back to 0 (equally spaced
IP/10 steps). The sensitivity S is defined as the slope of thelinear regression line for a cycle between ±IP N.
The linearity error εL is the maximum positive or negative
difference between the measured points and the linear
regression line, expressed in % of IP N.

Simplified transducer model
The static model of the transducer with voltage output attemperature TA is:
Uout = S · ΘP · (1 + ε)
In which (referred to primary):ε · ΘP = IO E + IO T + εS · ΘP + εS T · ΘP + εL(ΘP max) · ΘP max + IO M
ΘP = NP · IP	: primary current linkage (A)ΘP max: maximum primary current linkage applied tothe transducerIS		: secondary current (A)Uout		: output voltage (V)S		: sensitivity of the transducerTA		: ambient operating temperature (°C)
IO E		: electrical offset current (A)IO M		: magnetic offset current (A)IO T		
: temperature variation of IO E (A)εS		: sensitivity error at 25 °C
εS T		: thermal drift of S
εL(ΘP max) 		
: linearity error for ΘP max
This model is valid for primary ampere-turns ΘP between−ΘP max and +ΘP max only.
This is the absolute maximum error. As all errors are
independent, a more realistic way to calculate the error would
be to use the following formula:

ε=

N

∑ε i2
i =1

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LWSR 250-P

Performance parameters definition
Magnetic offset referred to primary

Total error referred to primary

The magnetic offset current IO M is the consequence of a current
on the primary side (“memory effect” of the transducer’s ferromagnetic parts). It is measured using the following primary
current cycle. IO M depends on the current value IP ≥ IP N.

The total error εtot is the error at ±IP N, relative to the rated value
IP N.
It includes all errors mentioned above● the electrical offset IO E
● the magnetic offset IO M

Primary current cycle● the sensitivity error εS● the linearity error εL (to IP N).

0-1

Total error ℇtot
at UC = ... V and TA = 25 °C

0.12

aver. + 3σ

0.10
0.08
1

2

3

4

5

Step

KOL: Overload factor
Figure 1: Current cycle
andelectrical

IO M =ℇtot (% IP N)

with KOL = 1 .. 10

IP / (KOL · IP N)

1

IO M (max) / IP N

0.06

=

0.04

IO E (max) / IP N

0.02

used to measureoffset(transducer

magnetic
supplied)

0.00
-0.02

IP (3) − IP (5)
2

-1

-0.5
0
0.5
IP / (KOL · IP N) with KOL = 1 ... 10

1

Figure 3: Total error εtot

Electrical offset referred to primary
Using the current cycle shown in figure 3, the electrical offset
current IO E is the residual output referred to primary when the
input current is zero.

IO E =

IP(3) + IP(5)2The temperature variation IO T of the electrical offset current
IO E is the variation of the electrical offset from 25 °C to theconsidered temperature.

I O T (T )  I O E (T )  I O E (25 °C)

Delay times
The delay time tD 10 @ 10 % and the delay time tD 90 @ 90 % withrespect to the primary are shown in the next figure.
Both slightly depend on the primary current di/dt.
They are measured at nominal current.
I
100 %
90 %

IS

IP
tD 90
10 %

tD 10

t

Figure 2: tD 10 (delay time @ 10 %) and tD 90 (delay time @ 90 %)25May2023/Version 2

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LWSR 250-P
Application information
Filtering and decoupling
Supply voltage UC
The transducer has internal decoupling capacitors, but in the case of a power supply with high impedance, it is highly recommended
to provide local decoupling (100 nF or more, located close to the transducer) as it may reduce disturbance on transducer output
Uout and reference Uref due to high varying primary current. The transducer power supply rejection ratio is low at high frequency.

Output Uout
The output Uout has a very low output impedance of typically 1 Ohm; it can drive capacitive loads of up to 100 nF directly. Adding
series resistance Rf of several tenths of Ohms allows much larger capacitive loads Cf (higher than 1 µF). Empirical evaluation may
be necessary to obtain optimum results. The minimum load resistance on Uout is 1 kOhm.

Reference Uref
Likewise output Uout, the Uref has a very low output impedance of typically 1 Ohm; it can drive capacitive loads of up to 100 nF
directly. Adding series resistance Rf of several tenths of Ohms allows much larger capacitive loads Cf (higher than 1 µF). Empiricalevaluation may be necessary to obtain optimum results. The minimum load resistance on Uref is 10 kOhms.

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LWSR 250-P
External reference voltage
The REF pin can be used either as a reference voltage output or as a reference voltage input.
When used in reference voltage output, the internal reference voltage Uref is used by the transducer as the reference point for
bipolar measurements.
The internal reference voltage output accuracy is defined in the electrical parameter data.
When used in reference voltage input, an external reference voltage is connected to the REF pin.
In this case, the maximum allowable reference voltage range is 0.5 V - 2.75 V.
The REF pin must be able to source or sink an input current of 1.5 mA maximum.
If the reference voltage is not used, the REF pin should be left unconnected.
The following graph shows the IP current versus forced extreme external Uref.

600
400
200

2.75 VIP (A)

0

-200
-400
-600

0.5

1

1.5

2

2.5

3

UUrrefef (V)Figure 4: Measuring range versus external Uref

Upper limit:

IP = 380 (Uref = 0.5 V ... 2.75 V)

Lower limit: IP = −257* Uref + 27 (Uref = 0.5 V ... 1.5 V)
		IP = −380 (Uref = 1.5 V ... 2.75 V)
Example with Uref = 1 V
The transducer has a measuring range from −240 A to +380 A.
Example with Uref = 0.5 V
The transducer has a measuring range from −80 A to +380 A.

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Uref

Uref

LWSR 250-P
PCB footprint according to the product (in mm)

Assembly on PCB● Recommended PCB hole diameter					● Maximum PCB thickness		● Wave soldering profile		
No clean process only

1.2 mm for secondary pin
3.2 mm for retention pin
2.4 mmmaximum 260 °C for 10 sExternal Busbar recommendation
Illustration of External Busbar influence on εtot
10

20

50

100

200

εtot @ Busbar IP = +IP N (%)–0.446–0.374–0.255–0.160–0.090εtot @ Busbar IP = –IP N (%)

0.402

0.330

0.211

0.116

0.046

a (mm)

10

20

50

100

200

εtot @ Busbar IP = +IP N (%)

0.480

0.403

0.260

0.156

0.081

εtot @ Busbar IP = –IP N (%)–0.463–0.391–0.247–0.142–0.067

10

20

50

100

200

εtot @ Busbar IP = +IP N (%)–0.666–0.525–0.313–0.179–0.095εtot @ Busbar IP = –IP N (%)

0.626

0.485

0.273

0.139

0.055

a (mm)a (mm)

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LWSR 250-P
Dimensions (in mm)

Connection
UC

RM

Uref

Uout
Uref
RM

Mechanical characteristic● General tolerance

Remarks±0.6 mm● It is advised to use a primary conductor (busbar) that fills
transducer through-hole.
● Be aware of the influence of the external field if nearby
transducers are too close (relay, capacitor, choke...).
● Installation of the transducer must be done, unlessotherwise specified on the datasheet, according to LEM
Transducer 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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Uref