TM 55-4920-221-14
121. THREE-PHASE CURRENT TRANSFORMERS.
(11) Remove relay from panel (2) by removing
two screws (16).
a. Removal.
(12) Remove other two relays in similar
(1) Tag and disconnect leads on the three-
manner.
phase transformer (1, figure 12).
(13) Remove terminal block (9) from panel by
NOTE Do not remove wires from around
removing two screws (8).
transformers.
c. Cleaning, Inspection, and Repair.
(2) Remove transformer plate (7) from frame
inside control panel by removing two screws (8) and
(1) Clean parts with a cloth dampened in dry
nuts (9).
cleaning solvent P-D-680 and dry thoroughly.
(3) Remove two nuts (5), washers (6), and
(2) Inspect resistors for cracks, breaks, burns
screws (2) securing transformer (1) to transformer plate
or discoloration, and damaged terminal leads.
(7).
(3) Inspect relays for cracked or damaged
(4) Remove clamping strip (3), transformer
base and defective coil.
(1) and channel (4) from plate.
(4) Inspect relay for damaged terminals and
(5) Remove other two transformers in a
burned or pitted contacts.
similar manner.
(5) Inspect other parts for damage and
b. Installation.
unserviceable condition.
(1) Install channel (4), transformer (1), and
d. Reassembly.
clamping strip (3) on transformer plate (7) with two
(1) Attach terminal block (9) on panel (2) with
screws (2), washers (6), and nuts (5).
two screws (8).
(2) Install other two transformers in a similar
(2) Attach relay (14) on panel (2) with two
manner.
screws (16).
(3) Attach assembled transformers and plate
(3) Connect leads to relay.
on frame of control panel with two screws (8) and nuts
(4) Install other two relays in a similar
(9).
manner.
(4) Connect leads to transformer.
(5) Attach contactor (10) on contactor bracket
(11) with four screws (12).
122. SINGLE-PHASE CURRENT TRANSFORMER.
(6) Attach assembled contactor on panel (2)
a. Removal.
with two screws (13).
(1) Remove T1 variable control (paragraph
(7) Connect the electrical leads.
117a(6)).
(8) Attach rectifier brackets (4) on rectifier (7)
(2) Tag and disconnect leads attached to
with two nuts (6).
single-phase current transformer and shunt assembly
(9) Attach assembled rectifier on panel (2)
(43, figure 12).
with two screws (5).
(3) Remove current transformer and shunt
(10) Connect the electrical leads.
assembly (43) from control panel by removing two nuts
(11) Attach resistor (1) on panel (2) with two
(47) and screw (45).
screws (3).
b. Disassembly.
(12) Connect electrical leads.
(1) Remove two nuts (6, figure 13),
(13) Attach variable resistor (17) in a similar
lockwashers (5), screws (2), and clamping strip (3)
manner.
securing transformer (1) to channel (4).
c. Installation.
(2) Remove transformer and channel from
(1) Attach nameplate (45, figure 10) on panel
plate (14).
with four screws (46).
(3) Remove shunts (7) from brackets (11), by
(2) Attach pushbutton switches (33 and 34) in
removing two nuts (10) and screws (9).
panel with knurled nuts (36).
(4) Remove shunt (8) in a similar manner.
(3) Install pushbutton (35) on pushbutton
(5) Remove bracket (11) from plate (14) by
switch (33).
removing nut (13), and screw (12).
(4) Connect electrical leads to two pushbutton
(6) Remove other bracket in a similar
switches.
manner.
(5) Place panel (2, figure 11), with attaching
c. Cleaning, Inspection, and Repair.
parts on frame and secure with three screws (15).
(1) Clean parts with a cloth dampened in dry
(6) Connect electrical leads to terminal block
cleaning solvent PD-680 and dry thoroughly.
(9) and three relays (14).
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