TB MRI(K)3-C 03.02 E
7
3.1.1 Analog input circuits
The analog input signals of the phase currents I
L1
(B3 -
B4), I
L2
(B5 - B6), I
L3
(B7 - B8) and the earth current I
E
(B1 - B2) are fed to the protection device via separate
input CTs. The current measuring quantities are gal-
vanical decoupled, analogously filtered, and then fed
to the analog/digital converter.
For the unit type with earth fault directional features
(ER/XR-relay type) the residual voltage from the open
delta winding can directly be connected to A3 and
A2.
See chapter ??? for voltage transformer connections
on isolated/compensated systems (direction feature of
the aerth fault element)
3.1.2 Output relays
The
MRI(K)3-C
has 5 output relays. Two of these re-
lays with two change-over contacts and three relays
with one change-over contact each are used for sig-
nalling. The protective functions can be freely allo-
cated except of those for the self-supervision relay.
•
Relay 1: C1, D1, E1 and C2, D2, E2
•
Relay 2: C3, D3, E3 and C4, D4, E4
•
Relay 3: C5, D5, E5
•
Relay 4: C6, D6, E6
•
Relay 5: Self-supervision C7, D7, E7
All relays are operating according to the n. o. princi-
ple with the exception of the self-supervision relay,
which operates acc. to the n. c. principle.
3.1.3 Digital inputs
The
MRI(K)3-C
has 7 digital inputs with fixed func-
tions. The input functions can be selected free for each
digital input. All inputs have a common reference point
: Terminal D8. (See chapter 5.11.4/5.11.5)
Terminal
Function
Code
jumper
C8
Digital Input 1
2
E8
Digital Input 2
1
A2
Digital Input 3
3
A5
Digital Input 4
4
A6
Digital Input 5
7
A7
Digital Input 6
6
A8
Digital Input 7
5
3.1.4 Low/High range of the digital
Inputs
The
MRI(K)3-C
is equipped with a wide-range power
supply unit and hence the supply voltage is freely se-
lectable. The switching threshold of the digital inputs,
however, has to be fixed in compliance with the sup-
ply voltage. Two different switching thresholds can be
adjusted:
Range
Plug
U
AB
U
AN
Low
Plugged in
<= 8V
>= 10V
High
Open
<= 60V
>= 70V
Figure 3.5
: Code jumpers
