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9November2011/version 14 LEM reserves the right to carry out modications on its transducers, in order to improve them, without prior notice www.lem.com
Current Transducer LA 25-NP
For the electronic measurement of currents: DC, AC, pulsed...,
with galvanic isolation between the primary circuit and the secondary
circuit.
Electrical data
IPN Primary nominal current rms 25 At
IPM Primary current, measuring range 0 .. ± 36 At
RM Measuring resistance @ TA = 70°C TA = 85°C
RM min RM max RM min RM max
with ± 15 V @ ± 25 At max 100 320 100 315 Ω
@ ± 36 At max 100 190 100 185 Ω
ISN Secondary nominal current rms 25 mA
KN Conversion ratio 1-2-3-4-5 : 1000
VC Supply voltage (± 5 %) ± 15 V
IC Current consumption 10 + IS mA
Accuracy - Dynamic performance data
X Accuracy @ IPN, TA = 25°C ± 0.5 %
εL Linearity error < 0.2 %
Typ Max
IO Offset current 1) @ IP = 0, TA = 25°C ± 0.05 ± 0.15 mA
IOM Magnetic offset current 2) @ IP = 0 and specied RM,
after an overload of 3 x IPN ± 0.05 ± 0.15 mA
IOT Temperature variation of IO 0°C .. + 25°C ± 0.06 ± 0.25 mA
+ 25°C .. + 70°C ± 0.10 ± 0.35 mA
- 25°C .. + 85°C ± 0.5 mA
- 40°C .. + 85°C ± 1.2 mA
tr Response time 3) to 90 % of IPN step < 1 µs
di/dt di/dt accurately followed > 50 A/µs
BW Frequency bandwidth (- 1 dB) DC .. 150 kHz
General data
TA Ambient operating temperature - 40 .. + 85 °C
TS Ambient storage temperature - 45 .. + 90 °C
RP Primary coil resistance per turn @ TA = 25°C < 1.25 mΩ
RS Secondary coil resistance @ TA = 70°C 110 Ω
 @ TA = 85°C 115 Ω
RIS Isolation resistance @ 500 V, TA = 25°C > 1500 MΩ
m Mass 22 g
Standards EN 50178: 1997
Notes: 1) Measurement carried out after 15 mn functioning
2) The result of the coercive eld of the magnetic circuit
3) With a di/dt of 100 A/µs.
IPN = 5-6-8-12-25 At
Features
● Closed loop (compensated)
current transducer using the Hall
effect
● Isolated plastic case recognized
according to UL 94-V0.
Advantages
● Excellent accuracy
● Very good linearity
● Low temperature drift
● Optimized response time
● Wide frequency bandwidth
● No insertion losses
● High immunity to external
interference
● Current overload capability.
Applications
● AC variable speed drives and
servo motor drives
● Static converters for DC motor
drives
● Battery supplied applications
● Uninterruptible Power Supplies
(UPS)
● Switched Mode Power Supplies
(SMPS)
● Power supplies for welding
applications.
Application domain
● Industrial.
16080
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9November2011/version 14 LEM reserves the right to carry out modications on its transducers, in order to improve them, without prior notice www.lem.com
Current Transducer LA 25-NP
Isolation characteristics
Vd Rms voltage for AC insulation test, 50 Hz, 1 min 2.5 kV
Vw Impulse withstand voltage 1.2/50 µs 9 kV
Min
dCp Creepage distance 10.63 mm
dCI Clearance 10.63 mm
CTI Comparative Tracking Index (group IIIa) 175
Applications examples
According to EN 50178 and IEC 61010-1 standards and following conditions:
● Over voltage category OV 3
● Pollution degree PD2
● Non-uniform eld
Safety
This transducer must be used in electric/electronic equipment with respect
to applicable standards and safety requirements in accordance with the
manufacturer’s operating instructions.
Caution, risk of electrical shock
When operating the transducer, certain parts of the module can carry hazardous
voltage (eg. primary busbar, power supply).
Ignoring this warning can lead to injury and/or cause serious damage.
This transducer is a build-in device, whose conducting parts must be inaccessible
after installation.
A protective housing or additional shield could be used.
Main supply must be able to be disconnected.
EN 50178 IEC 61010-1
dCp, dCI, Rated insulation voltage Nominal voltage
Basic insulation 1700 V 1700 V
Reinforced insulation 600 V 600 V
V
w
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9November2011/version 14 LEM reserves the right to carry out modications on its transducers, in order to improve them, without prior notice www.lem.com
Dimensions LA 25-NP (in mm)
Number of
primary turns
Primary current Nominal
output current
ISN [mA]
Turns ratio
KN
Primary
resistance
RP [mΩ]
Primary insertion
inductance
LP [µH]
Recommended
connections
nominal
IPN [A]
maximum
IP [A]
125 36 25 1 / 1000 0.3 0.023
5 4 3 2 1 IN
OUT 6 7 8 9 10
2 12 18 24 2 / 1000 1.1 0.09
5 4 3 2 1 IN
OUT 6 7 8 9 10
3 8 12 24 3 / 1000 2.5 0.21
5 4 3 2 1 IN
OUT 6 7 8 9 10
469 24 4 / 1000 4.4 0.37
5 4 3 2 1 IN
OUT 6 7 8 9 10
5 5 725 5 / 1000 6.3 0.58
5 4 3 2 1 IN
OUT 6 7 8 9 10
Mechanical characteristics
● General tolerance ± 0.2 mm
● Fastening & connection of primary 10 pins 0.7 x 0.6 mm
● Fastening & connection of secondary 3 pins Ø 1 mm
● Recommended PCB hole 1.2 mm
Connection
Remarks
●IS is positive when IP ows from terminals 1, 2, 3, 4, 5 to
terminals 10, 9, 8, 7, 6.
● This is a standard model. For different versions (supply
voltages, turns ratios, unidirectional measurements...),
please contact us.