Accessibility; Transformer Sound Levels - HPS DH Serie Guía De Instalación, Operación Y Mantenimiento

Accessibility

CAUTION
Failure to follow accessibility instructions can result
in injury and/or property damage.

Transformer Sound Levels

for conduits in the front of the transformer should not obstruct
more than 50% of the front ventilation area defined between
the bottom plate and the supporting legs. Please see the Cable
Connection Requirements section on page 8 for instructions.
NEC standards require that transformers be accessible for
inspection and located accordingly.
However, transformers should not be located in areas
where stored items are likely to interfere with either natural air
convection or the capability to have them inspected. Passage
ways or other areas where people could be exposed to live
parts during inspection should also be avoided.
Adequate protection should be provided under any
circumstances.
Transformers are an electrically energized apparatus and
by their nature during normal operation will emit a certain level
of sound.
Transformers are required to meet NEMA standards for
the maximum sound levels permissible. These sound level
standards vary from 40 to 67 dB and as such may be an
annoyance if located in close proximity to where people work
or reside.
Care should therefore be exercised in selecting sites
for transformers particularly in sensitive areas like hospitals,
classrooms, medical or office facilities.
The following guidelines may be helpful:
Units should be mounted away from corners or reflecting

walls or ceilings.
Cable or other flexible conduit should be considered to

make the incoming/ outgoing connections.
All dry-type transformers are provided with isolation

anti-vibration pads between the core and coil assembly
and the enclosure. However, sound absorbing vibration
isolators may also be installed between the transformer
and its mounting surface.
Depending on the environment, to reduce noise

acoustically absorbing materials could be considered for
walls and ceilings around the unit.
The location of the unit should be as far as practical

from areas where sound levels could be considered
undesirable.
7
IOMGDDI / September 2017