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8March2012/version 7

LEM reserves the right to carry out modifications on its transducers, in order to improve them, without prior notice

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CAS series

Response and reaction times

The response time tr and the reaction time tra are shown in

figure 31.

Both depend on the primary current di/dt. They are measured

at nominal ampere-turns.

Figure 31: Response time t

Figure 32: Test connection

Electrical offset

The electrical offset voltage

V

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 in figure 30.

Using the current cycle shown in figure 30, the electrical offset

is:

The temperature variation

V

V

considered temperature:

Note: the transducer has to be demagnetized prior to the

application of the current cycle (for example with a

demagnetization tunnel).

Overall accuracy

The overall accuracy at 25°C

X

range, relative to the rated value

I

It includes:

● the electrical offset

V

OE

● the sensitivity error

ε

G

● the linearity error

ε

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

Performance parameters definition (continued)

2

)

(

)

(

2

1

t

V

t

V

V

OUT

OUT

OE

+

=

)

25

(

)

(

)

(

C

V

T

V

T

V

OE

OE

OT

°

−

=

90 %

10 %

t

100 %

I