LEM reserves the right to carry out modications on its transducers, in order to improve them, without prior notice.
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Current Transducer LF 305-S
For the electronic measurement of currents: DC, AC, pulsed...,
with galvanic isolation between the primary circuit (high power)
and the secondary circuit (electronic circuit).
Electrical data
IPN Primary nominal current rms 300 A
IPM Primary current, measuring range 0 .. ± 500 A
RM Measuring resistance @ TA = 70°C TA = 85°C
RM min RM max RM min RM max
with ± 12 V @ ± 300 A max 0 37 0 35 Ω
@ ± 500 A max 0 10 0 8 Ω
with ± 15 V @ ± 300 A max 0 56 0 54 Ω
@ ± 500 A max 0 21 0 19 Ω
with ± 20 V @ ± 300 A max 0 88 0 86 Ω
@ ± 500 A max 0 40 0 38 Ω
ISN Secondary nominal current rms 150 mA
KN Conversion ratio 1 : 2000
VC Supply voltage (± 5 %) ± 12 .. 20 V
IC Current consumption 26 (@± 20V)+ IS mA
XG Overall accuracy @ IPN , TA = 25°C ± 0.5 %
Accuracy - Dynamic performance data
εL Linearity error < 0.1 %
Typ Max
IO Offset current @ IP = 0, TA = 25°C ± 0.2 mA
IOM Magnetic offset current 1) @ IP=0 and specied RM
after an overload of 3 x IPN ± 0.2 mA
IOT Temperature variation of IO - 40°C .. + 85°C ± 0.2 ± 0.7 mA
- 10°C .. + 70°C ± 0.1 ± 0.3 mA
tra Reaction time to 10 % of IPN < 500 ns
tr Response time 2) to 90 % of IPN step < 1 µs
di/dt di/dt accurately followed > 100 A/µs
BW Frequency bandwidth (- 1 dB) DC .. 100 kHz
TA Ambient operating temperature - 40 .. + 85 °C
General data
TS Ambient storage temperature - 40 .. + 85 °C
RS Secondary coil resistance @ TA = 70°C 30 Ω
TA = 85°C 32 Ω
m Mass 95 g
Standards EN 50178:1997
Notes:1) The result of the coercive eld of the magnetic circuit
2) With a di/dt of 100 A/µs.
IPN = 300 A
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 domains
Industrial. ●
16167
LEM reserves the right to carry out modications on its transducers, in order to improve them, without prior notice.
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Current Transducer LF 305-S
Isolation characteristics
Vd Rms voltage for AC isolation test, 50 Hz, 1 min 3.8 kV
Vw Impulse withstand voltage 1.2/50 µs 10 kV
Min
dCp Creepage distance 11.9 mm
dCI Clearance distance 11.5 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 2 ●
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
1000 V
1000 V
Reinforced insulation
500 V
500 V
Vw
LEM reserves the right to carry out modications on its transducers, in order to improve them, without prior notice.
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Connection
Dimensions LF 305-S (in mm.)
Mechanical characteristics
General tolerance ± 0.5 mm ●
Transducer fastening ●
Vertical position 2 holes Ø 4.3 mm
2 M4 steel screws
Recommended fastening torque 3.2 Nm
or 4 holes Ø 1.9 mm,
depth: 7 mm
4 PTKA 25 screws
length: 6 mm
Recommended fastening torque 0.7 Nm
Transducer fastening ●
Horizontal position 4 holes Ø 4.3 mm
4 M4 steel screws
Recommended fastening torque 3.2 Nm
or 4 holes Ø 1.9 mm
crossing
4 PTKA 25 screws,
length: 10 mm
Recommended fastening torque 0.75 Nm
Primary through-hole Ø 20.1 mm ●
Connection of secondary Molex 6410 ●
3 Tin plated pins
Remarks
I ●S is positive when IP ows in the direction of the arrow.
Temperature of the primary conductor should not exceed ●
100°C.
Dynamic performances (di/dt and response time) are ●
best with a single bar completely lling the primary hole.
This is a standard model. For different versions (supply ●
voltage, turns ratios, unidirectional measurements ...),
please contact us.
