Instruction manual

KRB-5377
79
Table 42 Normal inspection procedure
Check point No. Check item Description
1
Discoloration
of conductors
Check connection conductors, main circuit terminals, and current carrying parts for heat
discoloration. If such a symptom is found, contact us.
2Parts missing
Check that screws, bolts, nuts, washers, springs, retainers and the like are not missing. If any parts
are missing, contact us.
3
Damage to
parts
Check for deformation, cracks, chips, rust, or other damage of parts. If damage is found, contact us.
General
(*1)
4
Dust
accumulation
Check that no dust is accumulated in ACB. If dust is accumulated, use vacuum cleaner to remove
dust and wipe off with dry, clean cloth.
Main/control
circuit terminals
See 2-3.
5 Connections
Check main circuit terminal screws, ground terminal screw, auxiliary switch terminal screws, control
circuit terminal screws, and position switch terminal screws for looseness. If loose, tighten to
specified torque.
Main/control
circuit contacts
See 4-2.
6
Surface
condition
Draw out the breaker body from draw-out cradle and check that contacts have no dust accumulation
and discoloration. If dust is accumulated, use vacuum cleaner to remove dust and wipe off with dry,
clean cloth. If surface is discolored badly, polish it with #200 sandpaper. (*2) For main circuit
contacts, apply contact grease (SS grease, No. F-5G, FUJI KAGAKU SANGYO) to contact surface
after cleaning.
z Excessive grease may foster dust accumulation. Grease should be applied lightly.
z Blackening of contacts is caused by oxidation or sulfuration and has no harmful effect except in
extreme cases. If heat discoloration, arc marks, roughness, or peeling of plating layer is found,
contact us.
Arc chamber
See 6-2-2.
7
Dust
accumulation
/Damage
Remove arc chamber and check it for foreign object or dust accumulation, deformation, cracks,
chips and other damage. If foreign matter or dust is accumulated, use vacuum cleaner to remove
foreign matter of dust and wipe off with dry, clean cloth. If metal spatters are adhered, use
sandpaper to remove them. (*2) If arc chamber has stubborn adherents suffers damage, replace arc
chamber.
Main circuit, Arc
chamber
See 6-2-2.
8
Insulation
resistance
Close ACB and, using DC500V Megger, check that insulation resistance between main circuit
terminals, between main circuit terminal group and ground, and between ends of adjacent grids
exceeds 5M ohm. If resistance does not exceed 5M ohm, use sandpaper to remove carbonized
portions of insulation around contacts or current carrying parts and/or spatters adhered to arc
chambers and arc extinguishing grids. (*2) If problem persists, contact us.
9
Surface
condition
Remove arc chamber and check contact circumference, contacts, and contact tips for foreign object
or dust accumulation, deformation, cracks, chips and other damage. If dust is accumulated, use
vacuum cleaner to remove dust and wipe off with dry, clean cloth. If contact tips are badly discolored
or roughened, polish with #200 sandpaper. (*2) If contact tip suffers damage or is less than 0.7 mm
thick after polishing, replace both moving and stationary contacts.
z Blackening of contact tips is caused by oxidation or sulfuration and will be removed during closing
operation. It has no harmful effect except in extreme causes. If heat discoloration is found,
perform detailed inspection.
Contacts
See 6-2-2, 6-2-
3 and 6-2-4.
10
Looseness of
screws
Check moving and stationary contact mounting screws A and B for looseness. Also check the
moving arcing contact mounting nut for looseness when ship classification society rules apply. If
loose, retighten.
Control circuit
See 6-2-5.
11 Wiring
Remove side and front covers, check that wiring is properly connected, and not disconnected nor
damaged. If incorrect connection is found, connect correctly. If disconnection or damage is found,
contact us.
Operating
mechanism
See 6-2-7.
12
Internal
mechanism
With OCR removed, check internal mechanism for missing parts, deformation, cracks, chips, foreign
mater or dust accumulation, breakage of springs, and rust. If foreign matter or dust is accumulated,
use vacuum cleaner to remove foreign matter of dust and wipe off with dry, clean cloth. If any parts
are missing or damaged or springs are broken, contact us.
State of
operation lever
Current conducting
between _11 and _12
Current conducting
between _11 and _14
Natural position 100 mΩ or less Non
13 Operation
Check that auxiliary switches
operate as shown to the right.
If not so, replace switches.
Uppermost lift
position
Non
100 mΩ or less
14
Auxiliary
contacts
Remove auxiliary switches and check contacts for roughness. If roughened excessively, replace
contacts.
Auxiliary
switches
See 6-2-9.
15
Looseness of
screws
Check screws of auxiliary switches for looseness. If loose, retighten.
16
Draw-
out/insertion
mechanism
Draw out and insert breaker body to check that draw-out handle can be turned with max. operating
torque or less, position indictor provides correct indication, release button operates normally, and no
abnormal sound is heard during handle operation. If abnormality is found, contact us.
17 UVT
With breaker body in ISOLATED position, charge closing springs manually and attempt closing ACB
to make sure ACB cannot be closed. If ACB can be closed, perform detailed inspection.
Operation
related
mechanism
See 4-1 and 4-
2.
18
Operation
mechanism,
LRC, SHT and
UVT
With breaker body in TEST position and operation mechanism, SHT and UVT supplied with power,
perform closing spring charging operation and manual and electrical open/close operation several
times to check that charge indicator, ON-OFF indicator and ON-OFF cycle counter provide
correction indication and no abnormal sound is heard. If abnormality is found, perform detailed
inspection.
OCR and MHT 19 System alarm
Move the breaker body to the TEST position and supply the ACB with control power, and then check
that no system alarm appears on the OCR. If a system alarm appears, reset it. If the alarm cannot
be reset, see chapter 7.(AGR-21B,22B,31B)
*1 Always check the "General" items during the inspection procedure shown in Table 42 above.
*2 Take care to avoid grinding dust from entering the ACB. Wipe contact surfaces clean of grinding dust.