MC20-CEI
Doc. N°
MO-0431-ING
Microelettrica Scientifica S.p.A. - Copyright 2009
FW 1080.36.03.X
Date 18.11.2011
Rev.
3
Pag.
5
of 35
2. General Characteristics
The MC is a very innovative and versatile line of Protective Relays which takes advantage of the long and
successful experience coming from the M-Line.
The main features of the MC-Line relays are:
Compact draw-out execution for Flush Mounting or for assembly in 19” 3U chassis for 19” Rack systems.
User friendly front face with 2x8 characters LCD Display, four signal Leds, four keys for complete local
management and 9-pin socket for local RS232 serial communication.
Four user programmable Output Relays. On request one of the Output Relays can be replaced by a Can Bus port
for control of additional I/O modules.
Three optoisolated, self-powered Digital Inputs.
RS485 communication port (independent from the RS232 port on front panel)
Totally draw-out execution with automatic C.T. shorting device.
Input currents are supplied to 3 current transformers: - two measuring phase current - one measuring the earth
fault zero-sequence current.
Current inputs can be 1 or 5A, selection between 1A or 5A is made by movable jumpers provided on the Relay
card. (see Fig 1)
The Measuring Ranges of the different inputs
respectively are:
Phase Currents
: (0.1-40)In
Neutral Current
: (0.01-4)On
Make electric connection in conformity with the
diagram reported on relay's enclosure.
Check that input currents are same as reported on
the diagram and on the test certificate.
2.1 - Power Supply
The auxiliary power is supplied by a built-in module fully isolated an self-protected.
Two options are available:
24V(-20%) / 110V(+15%) a.c.
80V(-20%) / 220V(+15%) a.c.
a)
-
b) -
24V(-20%) / 125V(+20%) d.c.
90V(-20%) / 250V(+20%) d.c.
Before energizing the unit check that supply voltage is within the allowed limits.
