FHS-40-P-SP600 Datasheet, PDF (9/18 Pages) LEM – Current transducer FHS 40-P/SP600

FHS 40-P/SP600
0 - 100A
Application information
Basic operation: example with a long thin conductor
Minisens is a galvanically isolated current transducer. It senses the magnetic field generated by the measured current and
transforms it into an output voltage.
If the current is bidirectional, Minisens will sense the polarity of the magnetic field and generate a positive or negative output
voltage relative to the reference voltage.
A simple case is presented which illustrates the current to magnetic field and then to output voltage conversion.
A current flowing in a long thin conductor generates a flux density around it:
B = ^μ0 ⋅ ^IP (T)
2π r
with I_P
r
µ₀
the current to be measured (A)
the distance from the center of the wire (m)
the permeability of vacuum (physical constant, µ₀ = 4.π. 10^-7 H/m)
Figure 8: Minisens orientation to measure the magnetic field generated by a current along a conductor
If Minisens is now placed in the vicinity of the conductor (with its sensitivity direction colinear to the flux density B), it will sense
the flux density and the output voltage will be:
VS = GB ⋅ B = GB ⋅ ^μ0 ⋅ ^IP = 1.2 ⋅ 10 ^−4⋅ ^IP (V)
2π r
r
where G_B is the Minisens magnetic sensitivity (600 V/T)
The sensitivity is therefore: _{G =} ^VS ₌ ^{1.2 ⋅ 10 −4} _{(V / A)}
IP
r
The next graph shows how the ouput voltage decreases when r increases.
Note that the sensitivity also depends on the primary conductor shape.
100727/10
LEM reserves the right to carry out modifications on its transducers, in order to improve them, without prior notice.
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