Circutor Computer SMART III 6 Instruction Manual page 83

Computer SMART III
For other voltages or conditions not included in the table, the value of C/K can be obtained by means
of a simple calculation.
Calculating the C/K Factor
The equation for calculating the C/K factor is:
, Ic
where : is the smallest capacitor current.
K: the current transformer transformation ratio.
Ic
To calculate it is necessary to know the reactive power of the smallest capacitor Q and the network
voltage V.
The transformation ratio K is calculated as:
where, Iprim : is the nominal current of the transformer primary.
Isec: is the current of the transformer secondary.
Example: In a 400 V device the smallest capacitor is of 60 kvar with a current transformer having a
ratio of 500/5, and the calculation would be made as follows:
Current of the smallest capacitor,
K 500 5 / 100
K Factor = =
The C/K value is: 0.866.
If the power of 60 kvar is referenced at 440 V, it should be multiplied by Vred
in which case the C/K value of the previous example would be 0.72.
If the C/K is configured lower than the actual value, connections and disconnections
would occur continuously with few load variations (the system performs more opera-
tions than necessary).
If the C/K is configured higher, the regulator requires a higher demand for reactive
power in order to switch and perform fewer operations.
Press the key to enter edit mode. It is identified by the
digits to be modified.
Instruction Manual
I
C / K
= C =
K
Q
I =
C
3 V .
/
K = I I
sec
prim
60000
Ic:
I = = 8 6 6 , A
C
3 400
⋅
Q
3 ⋅ K ⋅ V
/440
2
symbol and the flashing of the
2,
83