IM30-DK
Doc. N° MO-0040-ING
Rev.
2
Pag.
5
of
34
Copyright 2010 - Microener
2.2
– Operation and Algorithms
2.2.1
– Input Quantities
System Frequency
The system frequency Fn can be set to 50 or 60 Hz
Current inputs (See Connection Diagram § 16)
The relay directly displays the r.m.s. value of Phase Currents “
IA, IB, IC
“ flowing in the Primary of
the input Current Transformers and refers all its measurements to that value.
To make the relay properly working with any C.T., when programming the relay settings we have to
load the value of the Rated Primary Current ”
In
“ of the phase CTs:
In
= (1-9999)A, adjustable in steps of 1A.
Similarly for the Residual (Zero Sequence) Current, we have to load the value of the Rated Primary
Current
On
=(1-9999)A, adjustable in steps of 1A.
If the input of the Earth Fault element is supplied by the Residual connection of the 3 phase CTs, we
shall set for
“
On
“ the same value as “
In
“.
If the input of the Earth Fault element is supplied by a separated Core Balance CT, or by another
CT, “ On “ value will be the Rated Primary Current of this CT, normally different from “ In “.
The Rated Secondary Current of the CTs, can be either 1A of 5A.
For the Phase Current inputs, 1A or 5A configuration can be selected by moving the jumpers
provided on the CT input card (see § 18).
For the Earth Fault Current input, configuration is obtained by the jumper “J4”.
Example :
Phase CTs 1500/5A and Core Balance CT 100/1A
Load In = 1500A and On = 100A
Configure CT input card with jumpers J1, J2, J3 in the 5A position.
Configure Earth Fault input in the 1A position by the jumper “J4”.