0600DB0302
2/03
Cedar Rapids, Iowa, USA
Data Bulletin
Operational Noise (Humming) in Electrical
Distribution Equipment
Retain for future use.
INTRODUCTION
Some operational noise and/or humming in electrical equipment can be
expected. If the noise is louder or otherwise different from one component to
another, investigation is recommended.
TROUBLESHOOTING
If excessive noise is detected, inspect the equipment for the following:
WARNING
HAZARD OF ELECTRICAL SHOCK, BURN,
OR EXPLOSION
Beware of potential hazards; wear personal
protection equipment and take adequate safety
precautions when inspecting equipment.
•
Loose bolts, current transformer mounting, doors, covers and similar
parts can resonate with the normal 60-cycle hum and cause excessive
noise/humming.
•
Extra hardware laying in equipment channels and similar type areas can
cause excessive noise/humming.
•
Open current transformers or improper wiring can cause excessive
noise/humming.
Failure to follow this instruction can result
in death or serious injury.
OPERATIONS
If the equipment inspection does not identify the cause, there are internal
components inside the circuit breaker that can affect the noise generated
while the circuit breaker is carrying current.
The tolerances of parts inside the circuit breaker can allow slight
movements caused by the magnetic fields and other forces inside the circuit
breaker. The movement of these parts can resonate at 60 Hertz causing
various amounts of noise and humming.
Tripping
Mechanism
Metal Arc
Chute Plates
Some circuit breakers or installations have higher levels of operational
noise/humming due to the tolerances between parts.
During the last 10–15 years, Square D has investigated several instances of
reported excessive noise/humming. In most of these instances, loose
hardware, wiring, and current transformers have been found to be the
cause. In the few instances that this was not the case, the circuit breakers
were evaluated and found to have acceptable performance and service life.
CONCLUSION
No evidence has been found to indicate that operational noise/humming is
detrimental to the performance or service life of the circuit breaker.
Square D Company
3700 Sixth St. SW
Cedar Rapids, IA 52404 USA
1-888-SquareD (1-888-778-2733)
www.SquareD.com
Electrical equipment should be installed, operated, serviced, and maintained only by
qualified personnel. No responsibility is assumed by Schneider Electric for any
consequences arising out of the use of this material.
© 2003 Schneider Electric All Rights Reserved
Operational Noise (Humming) in Electrical Distribution Equipment
—Conclusion
0600DB0302
2/03
ENGLISH
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© 2003 Schneider Electric All Rights Reserved