Thytronic NC020 - Protective Elements; Rated Values

FUNCTION CHARACTERISTICS
31
NC020 - Manual - 05 - 2022
4.4 PROTECTIVE ELEMENTS
— Rated values
• Relay phase nominal current I
n
This nominal value must be set by means dip-switch to 1 A or 5 A, same as the secondary CTs
nominal current.
Dip-switches are located on board of the CPU module; the exhaustive treatment of Dip setup is
described in the “6.5 SETTING NOMINAL CURRENTS I
n
AND I
En
” paragraph.
• Relay unbalance nominal current I
Nn
This nominal value must be set by means dip-switch to 1 A or 5 A, same as the secondary CT nomi-
nal current.
Dip-switch is located on board of the CPU module; the exhaustive treatment of Dip setup is de-
scribed in the “6.5 SETTING NOMINAL CURRENTS I
n
AND I
Nn
” paragraph.
• Phase CT primary current I
np
This parameter affects the measure of the phase currents when the Primary measurement read-
ing mode is selected. It must be programmed to the same value of the phase CT primary nominal
current.
Example
The phase CT primary current I
np
must be set as: I
np
= 500 A
• Relay unbalance CT primary nominal current I
Nnp
This parameter affects the measure of the neutral unbalance current when the primary measure-
ment reading mode is selected. It must be programmed to the same value of the neutral CT(s)
primary nominal current.
Example 1
The unbalance neutral CT primary current I
Nnp
must be set as: I
Nnp
= 100 A
Example 2
The unbalance neutral CT primary current I
Nnp
must be set as: I
Nnp
= 100 A
• Measurement reading mode
- With Reading Relative setting all measures are related to the nominal value,
- With Reading Direct setting all measures are related to the primary value.
Es-In.ai
K
CT
= 500A/5A=100
52
I
n
NC020
Es1-INn.ai
1x
K
CT
= 100 A /1 A
52
I
Nn
= 1 A
NC020
Es2-IEn.ai
3x
K
CT
= 100A / 5A
52
I
Nn
= 5 A
NC020