Bus Bars and Incoming Line Compartments
 DANGER |
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Hazard of Electric Shock, Explosion, or Arc Flash
Failure to follow these instructions will result in death or serious injury.
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HAZARD OF improper cleaning
Failure to follow these instructions can result in equipment damage.
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Initial Maintenance
Follow the steps below at the time of installation to locate and tighten any connections that may have loosened during shipment and handling:
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Turn off all power supplying this equipment before working on or inside the equipment and follow lockout/tagout procedures. Always use a properly rated voltage sensing device to confirm power is off.
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Remove the top and bottom horizontal wireway covers in each section.
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Expose the bus and bus connections by removing the two-piece bus barrier in each section.
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Examine all bus bars and connectors. Replace any parts that are badly discolored, corroded, pitted, or otherwise damaged.
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Verify that all bolts at the bus connection points indicated by a hexagon in Typical Bus Connection Points are in place and properly tightened. Although one specific type of compartment or bus is shown in Typical Bus Connection Points-Top-Feed ArcBlok Main Access, perform this maintenance on all bolted connections. See Bus Connection Torque Values for torque values.
Bus Connection Torque Values
Bolted Connection Location Torque Range Horizontal bus (all locations) 68–70 lb-ft. (92.29–94.54 N•m) Horizontal ground bus (all locations) 5–6 lb-ft. (6.75–8.44 N•m) Splice bars–0.375 in. diameter bolts 31–32 lb-ft. (41.64–43.33 N•m) Splice bars–0.5 in. diameter bolts 68–70 lb-ft. (92.29–94.54 N•m) Typical Bus Connection Points
Typical Top-Located 600 A or 800 A Main Lug Compartment
Typical Splice Bar Connection
Typical Horizontal Bus Connection
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Access to load-side connections for top-feed ArcBlok main sections are restricted by the cable vault, so an access panel in the cable vault provides access to B phase bus connections. Bus connections for A and C phases are located at the outer edges of the cable vault (See Typical Bus Connection Points-Top-Feed ArcBlok Main Access).
Typical Bus Connection Points-Top-Feed ArcBlok Main Access
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Verify that all main lug, circuit breaker, or fusible switch set screws holding incoming conductors in main lugs are in place and properly tightened (see Main Lug Compartment Torque Connection). Use a torque wrench and a 3/8 in. Allen bit to torque the lug set screws to the appropriate value (see Cable Connection Torque Values).
Main Lug Compartment Torque Connection
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Inspect all insulators, braces, and barriers; replace any that show signs of arcing damage, tracking, excessive heat, or cracking.
Periodic Inspection and Maintenance
Perform periodic inspection and maintenance of bus and incoming line lug connections at least annually or more frequently if indicated by service conditions and your established maintenance policy.
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Inspect the bus and line compartment connections for any signs of overheating. Discoloration and flaking of insulation or metal parts are indications of overheating.
NOTE: If overheating occurs, be sure all conditions that caused the overheating have been identified and corrected. Loose or contaminated connections can cause overheating. -
Replace bus bars and terminal lugs that display pitting, corrosion, or discoloration resulting from high temperatures or having been subjected to short circuit conditions.
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Tighten any loose connections found. See Initial Maintenance for information on bus and incoming line compartment connections.
NOTE: Bus bar and other joints that were tightened during initial maintenance and do not display signs of overheating or other signs of loosening do not need to be retightened. -
Inspect all insulating materials. Before re-energizing the MCC, replace insulators showing any visible damage (such as cracks).