This Standards Publication applies to single-phase and polyphase dry-type transformers (including autotransformers and non-current-limiting reactors) for supplying energy to power, heating, and lighting circuits and designed to be installed and used in accordance with the National Electrical Code.

It applies to transformers with and/or without accessories having the following ratings:

1. 1.2 kV class (600 volts nominal and below), 0.25 kVA and up.

2. Above 1.2 kV class sound level limits are supplied. These limits are applicable to commercial, institutional, and industrial transformers.

This Standards Publication applies to transformers, commonly known as general-purpose transformers, for commercial, institutional, and industrial use in nonhazardous locations both indoors and outdoors. The publication includes ratings and information on the application, design, construction, installation, operation, inspection, and maintenance as an aid in obtaining a high level of safe performance. These standards, except for those for ratings, may be applicable to transformers having other than standard ratings. These standards, as well as applicable local codes and regulations, should be consulted to secure the safe installation, operation, and maintenance of dry-type transformers.

This publication does not apply to the following types of specialty transformers: control, industrial control, Class 2, signalling, oil- or gas-burner ignition, luminous tube, cold cathode lighting, incandescent and mercury lamp. Also excluded are network transformers, unit substation transformers, and transformer distribution centers.

 

Customers who purchased NEMA ST 20
also purchased

• NEMA 250 : Enclosures for Electrical Equipment (1000 Volts Maximum)
• API SPEC 5L : Specification for Line Pipe-FORTY-FOURTH EDITION; Incorporating Errata: January 2009, Addendum 1: February 2009, Addendum 2: April 2010; Addendum 3: July 2011 Effective Date: January 1, 2012; ISO 3183:2007 Adoption
• API STD 650 CHINESE : Welded Tanks for Oil Storage-Eleventh Edition

See More Documents