Grounding - HPS EnduraCoil 1.2 KV Manual De Instrucciones

Sound Levels (continued)

Grounding

DANGER
HAZARD OF ELECTRIC SHOCK, EXPLOSION,
OR ARC FLASH
Failure to properly ground the transformer as per
all applicable codes and standards will result in
serious personal injury or death.
occur in a given area due to the presence of reflecting surfaces or
mounting surfaces.
Sound levels for transformers can vary from 60 dBA for a 500 kVA
to 76 dBA for a 10,000 kVA and more.
These sound levels are determined by CSA and ANSI/IEEE
Standards and are based on the following:
• Sound levels specified are for a non-loaded condition
at rated voltage and frequency
• Transformers are tested in a low ambient noise
environment
• Walls or reflecting surfaces are at least 10' away from
all sides of the transformer.
It should be noted therefore that operating transformers when
connected to a load, will exhibit higher sound levels than the
standards referenced. Additionally, transformers are frequently
installed in more confining electrical rooms which will have
the effect of increasing the apparent sound level due to sound
resonance. Transformers will exhibit higher than normal sound
levels if installed on suspended floors that may resonate. It is
a good practice to install power units on the ground floor or
basement level to avoid suspended floors and away from office
or living quarters. Vibration dampeners or spring isolators are also
recommended to attenuate sound levels if vibration is affecting
other parts of the building.
Flexible connectors can be installed between the bus bars and
other equipment to avoid vibration transfer. Ensure all mounting
bolts are tightened and that the transformer housing is securely
assembled and separate from the transformer itself.
Transformers installed in close proximity to each other can
experience a resonant frequency between them that results in
higher than normal sound levels.
If noise levels are a factor in the location of any transformer,
special consideration should be given to the installation site and
attenuation (accessories used). Interrupting the sound transmission
medium with the installation of sound absorbing foam or fiberglass
material on the ceiling or walls, could also be considered.
All non-current carrying metal parts in transformers must be
grounded as per all applicable standards, including the core
and enclosure. Standard construction has the core grounded
through direct contact with the clamping structure. Cores that
have metal bolts passing through them are insulated from
the core clamps and grounded at a single point. Isolating the
core rods in this manner is necessary on these transformers to
reduce the risk of circulating currents or hot spot. There are no
requirements for isolating cores in any standards including UL,
ANSI, CSA, IEEE and IEC.
11
IOMGCAS / May 2014