LAX-100-NP Datasheet, PDF (9/12 Pages) LEM – Current Transducer LAX SERIES

LAX series 16-100 A
Performance parameters definition (continued)
Electrical offset
Response and reaction times
The electrical offset current I can either be measured
OE
when the ferro-magnetic parts of the transducer are:
• completely demagnetized, which is difficult to realize, or
• in a known magnetization state, like in the current cycle
shown above.
Using the current cycle shown in figure 19, the electrical
offset is:
IOE
=
Is(t₁ ) + Is(t₂ )
2
The temperature variation I of the electrical offset current
OT
I_OE is the variation of the electrical offset from 25°C to the
considered temperature:
IOT (T ) = I_OE (T ) − I_OE (25°C)
Note: the transducer has to be demagnetized prior to the
application of the current cycle (for example with a
demagnetization tunnel).
The response time t_r and the reaction time t_ra are shown in the
next figure.
Both depend on the primary current di/dt. They are measured at
nominal ampere-turns.
The "di/dt accurately followed" mentionned in the electrical data
table is defined as the di/dt of the primary current for which the
response time is equal to 1 µs.
I
100 %
90 %
Ip
10 %
Is
tr
tra
t
Figure 20: response time t and reaction time t
r
ra
Overall accuracy
The overall accuracy at 25°C X_G is the error in the - I_PN .. + I_PN
range, relative to the rated value I .
PN
It includes:
• the electrical offset I_OE
• the sensitivity error ε_G
• the linearity error ε_L (to I_PN)
The magnetic offset is part of the overall accuracy. It is
taken into account in the linearity error figure provided the
transducer has not been magnetized by a current higher
than I .
PN
070615/8
LEM reserves the right to carry out modifications on its transducers, in order to improve them, without prior notice.
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