USE OF SPRING WASHERS ON ELECTRICAL CONNECTIONS
USE OF SPRING WASHERS ON ELECTRICAL CONNECTIONS
(OP)
Manufacturers and field installations seem to differ on the this. When using a a current carrying electrical connection such as bolting a commpression lug to a busbar or busbar to busbar, what is best connection method?






RE: USE OF SPRING WASHERS ON ELECTRICAL CONNECTIONS
RE: USE OF SPRING WASHERS ON ELECTRICAL CONNECTIONS
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RE: USE OF SPRING WASHERS ON ELECTRICAL CONNECTIONS
Maybe our mechanical friends could chip in on this one.
RE: USE OF SPRING WASHERS ON ELECTRICAL CONNECTIONS
RE: USE OF SPRING WASHERS ON ELECTRICAL CONNECTIONS
RE: USE OF SPRING WASHERS ON ELECTRICAL CONNECTIONS
old field guy
RE: USE OF SPRING WASHERS ON ELECTRICAL CONNECTIONS
A Belville washer is intended to maintain contact pressure and prevent bolt stretching and/or bus-bar cold flow during thermal expansion and compression cycles.
Different issues.
Different solutions.
Bill
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"Why not the best?"
Jimmy Carter
RE: USE OF SPRING WASHERS ON ELECTRICAL CONNECTIONS
A Belleville could work if properly applied. That's a big if though.
RE: USE OF SPRING WASHERS ON ELECTRICAL CONNECTIONS
RE: USE OF SPRING WASHERS ON ELECTRICAL CONNECTIONS
Bolt torque is poor indicator of contact pressure due to variability in friction.
Spring tension washers, if properly rated and properly installed (two big if's,) help assure the correct initial contact pressure and provide resilience for thermal expansion/contraction. Too often, even in good switchboard shops, there's one big box of belleville's that are used for everything. Also a spring washer squashed flat is useless.
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Alan
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"It's always fun to do the impossible." - Walt Disney
RE: USE OF SPRING WASHERS ON ELECTRICAL CONNECTIONS
In current carrying joints (say 500A or more) belleville spring washers(disc washers) are used to provide continuous pressure on contact areas to take care of the unequal expansion of current carrying parts and fasteners.The order of the bolting system is bolt head/belliville washer/ plain washer/ current carrying joint (two parts)/ plain washer/belleville/nut/projecting length of bolt.Plain washers are special ones having more OD to transmit the pressure from Belleville.These disc washers can be fitted in series(then their clamping load adds up) or in parallel(deflection adds up with same load)
Current carrying at a joint depends on the surface area(or A /mm2 normally 0.5 A/mm2 in oil and less value for air,surface finish and contact pressure.