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Specifications G e n e r a l
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SPECIFICATION GUIDE FOR DRY TYPE DISTRIBUTION TRANSFORMERS
1.0 Dry Type Transformers:
1.0.0 The following information should be utilized only by trained technical personnel. If you need assistance, please contact
Acme’s Technical Services Department at 800-334-5214.
1.0.1 Provide dry type, enclosed and ventilated transformers as indicated herein. Transformers shall be Acme or approved equal.
1.0.2 Transformers shall be designed, constructed and rated in accordance with UL, CSA, NEMA, ANSI, IEEE, and OSHA
standards.
1.0.3 Transformers rated 27 kVA and larger, single and three phase shall be the ventilated type, incorporating a 220 degree C
insulation system and designed not to exceed 150 degree C temperature rise above a 40 degree C ambient under full load
conditions. Taps are to be provided on the primary side of the transformer as follows:
(a) 2 - 2.5% above normal full capacity.
4 - 2.5% below normal full capacity.
-or-
(b) 2 - 2.5% above normal full capacity.
2 - 2.5% below normal full capacity.
Alternate 1: 115 degree C rise transformers shall incorporate a 220 degree C insulation system and be designed not to exceed
115 degree C temperature rise above a 40 degree C ambient under full load conditions. In addition, the transformer shall have
the ability to carry a continuous 15% overload without exceeding a 150 degree C rise above ambient.
Alternate 2: 80 degree C rise Transformers shall incorporate a 220 degree C insulation system and be designed not to exceed
80 degree C temperature rise above a 40 degree C ambient under full load conditions. In addition, the transformer shall have
the ability to carry a continuous 30% overload without exceeding a 150 degree C rise above ambient.
1.0.4 Transformer enclosure finish must be ASA 61 gray powder polyurethane paint. Transformer enclosure temperature shall not
exceed 50 degrees C plus the ambient under any condition of loading at any specified temperature rise at or below 150
degrees C.
1.0.5 Transformer enclosure shall be UL/NEMA Type 2 and UL 3R Listed with the addition of a weather shield and shall be so
marked on the transformer.
1.0.6 Transformer shall incorporate an electrostatic shield for the attenuation of voltage spikes, line noise, and transients.
1.0.7 Single phase transformers and three phase transformers terminate in copper or aluminum bus bar.
1.0.8 Transformer coils designed and manufactured for increased insulation life, cooler operation, and lower losses.
1.0.9 Transformers must operate at audible sound levels below NEMA Standard ST-20. Sound levels will not exceed the following:
30 - 50 kVA 45 db
51 - 150 kVA 50 db
151 - 300 kVA 55 db
301 - 500 kVA 60 db
501 - 750 kVA 65 db
Transformers must incorporate vibration isolation pads in their construction located between the transformer core and coil
assemblyand the transformer case. External vibration isolation pads will not be used as they tend to increase audible noise.
Transformers shall be floor mounted on a concrete pad. All connections to the transformer will be made by means of
flexible metallic conduit.
1.0.10 Transformer enclosure shall be grounded per the National Electric Code.
1.0.11 Transformers shall be dry-type 600volt class, kVA rating as indicated. Contractor to provide all necessary lugs for all
transformers.
1.0.12 Complete shop drawings must be submitted for approval on all dry type transformers.
1.0.13 Typical performance data must be submitted for approval on all transformers. Factory tests must be made in accordance with
the latest revisions of ANSI Test Code C57.12.91 for Dry Type Transformers. Performance data provided must contain but not
be limited to:
(a) No load losses.