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Ingeteam
I
: Rated primary current (A)
p
The rated primary current must be more than or equal to the maximum current per phase in the
system.
I
: Rated secondary current (A)
s
Value of the rated secondary current of the current transformer.
The rated current of the wattmeter to which the transformer secondary is to be connected is In = 5 A
and the maximum current of the same is Imax = 10 A.
To ensure the accuracy of the wattmeter measurement, it will be necessary to use at least one current
transformer with a rated secondary current of Is = 5 A.
For transformers with a rated secondary current of less than 5 A, Ingeteam does not guarantee
the accuracy and correct operation of the SMART DLM
You must not use a transformer with a rated secondary current of more than the maximum
wattmeter current, in other words 10 A
KN: Transformer ratio (A)
Ratio between the rated current of the primary and the rated current of the secondary. It is expressed
as a fraction. For example: KN = (150 A / 5 A).
Cl: Accuracy class
The accuracy class is the percentage current error limit when operating at rated current.
Ingeteam requires the accuracy class of current transformers to be 0.5 (Cl 0.5).
It is also acceptable to use current transformers whose accuracy class allows current measurements
to be made with an error of less than that specified for accuracy class 0.5.
S
: Precision power (VA)
n
This parameter describes the capacity of the transformer to pass a current through the secondary
through a load, while maintaining the accuracy class. It will be necessary to calculate the power
consumed in VA on the current transformer secondary (in this calculation, take into account the sum of
the wiring and the A65+ wattmeter).
We would recommend selecting a normalised power value that is as close as possible to the
calculated power, while the said normalised power must always be greater than the calculated power.
For correct operation, the following relationship must be met: If this relationship is not met, then
Ingeteam cannot guarantee the accuracy and correct operation of the SMART DLM:
Where:
S
: Power consumption at the A65+ wattmeter expressed in VA. The power dissipated by the
w
wattmeter for rated current I
16
S
≥ S
n
= 5A is Sw = 0.3 VA per phase.
n
+ S
w
c
SMART DLM
ABW2012IQM01_E.docx
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