GE Industrial Solutions Dry-Type General Purpose Power Transformers - Manual (Page 4)

4
CONTROL OF AUDIBLE SOUND SOURCES: Commercially available vibration isolators can be installed between the
transformer and it's mounting surface. This will reduce case vibration and compensate for slight unevenness of the mount. They
should be sized for the appropriate loading at twice the fundamental frequency. To eliminate possible sound generation, the
enclosure panel screws of the transformer housing must be tight and the housing must be securely fastened to the mounting surface.
Care must be taken to ensure proper and tight installation of conduit. Flexible conduit is recommended.
CONTROL OF AUDIBLE SOUND TRANSMISSION: Acoustical-absorbing material should be mounted on reflecting surfaces
to reduce sound reflection and possible amplification. Transformers should be mounted on a firm support having as great a mass as
possible. Vibration pads or properly designed isolation mounts under the transformer will reduce transmittal of sound. The
neoprene rubber isolation pads provided with the unit should be installed between the transformer and its mounting surface. This
will reduce case vibration and compensate for slight unevenness of the mount. Care must be taken to ensure proper and tight
installation of conduit. Flexible conduit is recommended.
KVA
(150C RISE)
AVERAGE SOUND
LEVEL IN DECIBELS
ANSI-C89.2
51-150 50
151-300 55
301-500 60
Dry type general-purpose transformers are designed and manufactured to comply with
NEMA and ANSI standards. The decibel values referenced here represent average
values obtained in a sound laboratory per industry standard test procedures. Decibel
values obtained in field testing are unreliable and can be as much as 10 to 15 dB
higher than actual test lab values due to a variety of circumstances beyond the control
of the transformer manufacturer. In most cases, transformers returned for noise
actually meet the ANSI standard when re-tested in a laboratory.
Some circumstances that can cause high field readings are:
•
Higher than rated voltage being applied to transformer windings (measured with a true RMS meter).
•
Isolation pads were not installed.
•
Transformer enclosure panels not properly tightened.
•
Improper installation of conduit.
•
Improper location of transformer. Mount the transformer as far away as possible from corners, walls or ceilings. Installing
transformers near hard surfaces such as concrete walls will amplify the sound requiring the use of sound absorbing materials.
CAUTION
CARE SHOULD BE USED IN SELECTING SITES FOR TRANSFORMER INSTALLATION. SPECIFIC ATTENTION
SHOULD BE GIVEN TO OFFICE, CLASSROOM, MEDICAL AND HOSPITAL FACILITIES. WHEN TRANSFORMERS
ARE LOCATED IN ELECTRICAL CLOSETS ADJACENT TO HALLWAYS, SOUND CAN BE GREATLY AMPLIFIED.
TRANSFORMERS SPECIFICALLY DESIGNED FOR LOW NOISE ARE AVAILABLE, CONTACT YOUR DISTRIBUTOR.
6.0 Connections
6.1 Cable Conduit Entrance / Lugs
All cable connections to the transformer should be brought into the enclosure as low as possible to allow for the required cable
bending radius. Side entry of cables is recommended as it leaves the ventilation areas unobstructed. When making cable
connection or changing taps, always use two wrenches for tightening or loosening bolted connections to prevent distortion or
damage. Note: terminals must be cleaned if it is necessary to change taps, gently scrape the insulation/coating from the new
connection and apply an electrical joint compound.
Bolt
Size Torque
(In Lbs.)
1/4” 60
5/16” 120
3/8” 220
All general-purpose transformers are designed for easy accommodation of cables and cable connectors.
Lug connector kits are readily available and can be ordered through the sales office, through the
distributor, or can be purchased commercially. The assembly of connectors to the line terminals is
important. Follow established installation procedures recommended by the connector manufacturer.
Do not install washers between the lug and the terminal, as this will cause heating and arcing, resulting
in failure of the connector. Refer to the NEC guide for sizing. Follow the torque recommendations of
the connector manufacturer or use the adjacent guide.
1/2” 460
WARNING
DO NOT REMOVE ENCLOSURE PARTS OR CHANGE CONNECTIONS WHILE THE UNIT IS ENERGIZED.