ABB REO 517 Applications Manual page 31

Terminal identification and base values
where:
I = secondary rated current of the main CT
SEC
I = primary rated current of the main CT
PRIM
Is = primary setting value of the current
The relay setting value IP>> is given in percentage of the secondary base current value,
Ixb, associated to the current transformer input Ix:
Is
SEC
⋅
IP>> = ------------- - 100
Ixb
The value of Ixb can be calculated as:
Rated primary current
Ixb --------------------------------------------------------- -
=
CT ratio
The voltage transformer secondary setting voltage (Us
U
SEC
⋅
--------------- - Us
Us =
SEC
U
PRIM
where:
U secondary rated voltage of the main VT
SEC
U primary rated voltage of the main VT
PRIM
Us primary setting value of the voltage
The relay setting value UPE< is given in percentage of the base voltage value, Uxb, as-
sociated to the voltage transformer input Ux:
&KDSWHU 
*HQHUDO
(Equation 11)
(Equation 12)
) is:
SEC
(Equation 13)
21