Inspection, Maintenance And Adjustment - ABB R-MAG Instruction Manual

9.0 INSPECTION, MAINTENANCE AND ADJUSTMENT

The R-MAG circuit breaker is an extremely simple device and requires minimal maintenance,
depending on the frequency of operation and local environmental conditions.
The safety and successful functioning of any apparatus or system connected with the breaker
largely depends on the proper and reliable operation of the unit.
To provide long reliable service, the breaker must have systematic inspections at regular inter-
vals. Operating experience based on environmental conditions, the number of operations, mag-
nitude of current and any unusual operation, will establish a maintenance schedule that gives
assurance of proper breaker reliability. The following check list is a minimum guide:
1. Check the phase assemblies for external damage and clean if contamination is evident.
2. Lubricate wear points and all pins in linkage assemblies with grease (Dow Corning 55
silicone lubricant).
3. Check contact wear. As a vacuum interrupter continues to perform, material from the butt
contacts is gradually eroded away, and the moving contact is driven deeper into the inter-
rupter by the operating mechanism. The over-travel spring at the upper end of the operating
rods ensures that proper contact pressure is maintained in the closed position. Contact ero-
sion reduces the compression of the over-travel spring, which in turn increases the contact
travel. (Total travel of the actuator is fixed.) See 9.3 for minor adjustments. Contact wear can
be visually inspected. A line is scribed on the moving contact stem 0.08" from VI end guide.
When the line reaches the VI end guide, replace vacuum interrupters. See Figures 3-8 and
Procedures 9.2 and 9.3. Contact wear can also be monitored by interruption magnitudes and
quantity.
4. Verify that the breaker operates correctly using the electrical controls.
5. A Hi-Pot test can be performed to verify the vacuum integrity (see section 7.2).
6. Contact Resistance: Measure contact resistance with suitable equipment rated not
less than 100 A. The value should not exceed 150 micro ohms.
7. Check heaters to verify proper operation.
8. When inspecting breaker, verify torque on current carrying parts are within tolerances:
.250-20 flex connectors
.375-16 bus connections
.500-13 bottle clamp*
*Note: This block must be supported when tightening. Do not exert a torque on the movable
contact of the vacuum interrupter, as damage may result.
Bushing clamp hardware (bushing flange mounted to roof) is aluminum and care must be
taken to prevent over tightening. Tighten aluminum nuts on bushing flange collar until lock
washers are compressed.
Values listed above are for grade 5 hardware. Contact the factory for other torque values.
7-10 ft-lbs
27-35 ft-lbs
65-80 ft-lbs
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