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Section 4. INSTALLATION, OPERATION AND MAINTENANCE
4.1
SEPARATING THE INNER AND
OUTERCHASSIS
It is recommended that the user of this equipment
become acquainted with the information in these in-
structions before energizing the MDAR and associ-
ated assemblies. Failure to observe this precaution
may result in damage to the equipment.
All integrated circuits used on the modules are sen-
sitive to and can be damaged by the discharge of
static electricity. Electrostatic discharge precautions
should be observed when operating or testing the
MDAR.
CAUTION
Use the following procedure when separating
the inner chassis from the outer chassis; failure
to observe this precaution can cause personal
injury, undesired tripping of outputs and compo-
nent damage.
a. Unscrew the front panel screw.
b. If the MDAR does not have FT-14 switches, but
has a power switch on the front panel, turn "OFF"
the power switch before sliding out the inner
chassis.
c. If the MDAR has FT-14 switches:
1) Remove the FT-14 covers (one on each
side of the MDAR).
2) Open all FT-14 switches.
WARNING: Do Not Touch the outer con-
tacts of any FT-14 switch;
they may be energized.
3) Slide out the inner chassis.
4) Close all FT-14 switches.
5) Replace the FT-14 covers.
d. Reverse procedures above when replacing the
inner chassis into the outer chassis.
4.2
TEST PLUGS AND FT-14 SWITCHES
Test Plugs are available as accessories (see Table
3-2); they are inserted into the FT-14 switches for the
purpose of System Function Tests. When the Test
(5/92)
Plugs are inserted, the terminals FT-14/13 (BP) and
FT-14/14(BN) must remain closed.
4.3
EXTERNAL WIRING
All external electrical connections pass through the
Backplate (Figure 4-1) on the outer chassis. If the
MDAR is used without the FT-14 switch, six 14-ter-
minal connectors on the Backplate (TB1 through
TB6) are used. If the FT-14 switch (option) is includ-
ed, using the two peripheral areas of the MDAR cab-
inet, then only four of the 14-terminal connectors
(TB2 through TB5) are used. Three DIN connectors
(J11, J12, J13) allow for the removal of the outer
chassis (Backplane module) from the inner chassis
(Interconnect module).
Electrical inputs to the Backplane module, which are
routed either directly through the Backplate or
through the FT-14 switch to the Backplate, include
(Figure 4-1):
• V
, V
, V
and V
A
B
C
N
• I
/I
, I
/I
, I
/I
, and I
A
AR
B
BR
C
CR
• BP (48, 125 or 250 Vdc) and BN (negative)
Analog input circuitry consists of four current trans-
formers (IA, IB, IC, and IN), three voltage transform-
ers, (VA, VB and VC), and low-pass filters. The sev-
en transformers are located on the Backplane PC
Board (see Appendix A). The primary winding of all
seven transformers are directly-connected to the in-
put terminal TB6/1 through 12 (see Functional Block
Diagram, Appendix J); the secondary windings are
connected through the Interconnect module to the
Filter module.
As shown in Figures 4-1 and 4-2, dry contact outputs
for breaker failure initiation (BFI), reclosing initiation
(RI), reclosing block (RB), failure alarm (AL1), trip
alarm (AL2), SEND and STOP are located on the
Backplane PC Board. Optical isolators are for Pilot
Enable, External Reset, Receiver #1 and #2, 52a,
52b, SBP (89b) and studs for chassis ground (GND)
and location for the Communication Interface are
also shown.
As shown in Figure 4-3, the power system ac quan-
tities (Va, Vb, Vc, Vn, Ia, Ib, Ic and In), as well as the
dc source are connected to the left side FT-14 switch
I.L. 40-385.1B
/I
P
N
4-1
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