UL 1004-4:2018 Electric Generators.
1.1 UL 1004-4 is intended to be read together with the Standard for Rotating Electrical Machines — General Requirements, UL 1004-1. The requirements in this Standard supplement or amend the requirements in UL 1004•1. The requirements of UL 1004-1 apply unless modified by this Standard.
1.2 This Standard covers electric generators, also referred to as alternators, which, when coupled with prime movers, such as engines or electric motors, are used to produce electricity. This Standard covers generators, including those for standby use rated 34,000 volts or less.
1.3 This Standard does not cover stationary or portable generator assemblies, which are respectively covered under the Standard for Stationary Engine Generator Assemblies, UL 2200, and the Standard for Carbon Monoxide (GO) Emission Rate of Portable Generators, UL 2201.
1.4 This Standard does not cover generators intended for use in hazardous locations as defined in the National Electrical Code ®, NFPA 70.
The National Electrical Code® and NEG® are registered trademarks of the National Fire Protection Association, Inc., Quincy, MA 02169.
1.5 In the context of this document, the term generators shall be understood to apply to both AC and DC machines.
2 Components
2.1 Voltage regulators shall comply with the following requirements:
a) The Standard for Industrial Control Equipment, UL 508;
b) The Standard for Electrical Equipment For Measurement, Control, and Laboratory Use; Part 1: General Requirements, UL 61010-1; or
c) The Outline of Investigation for Controls for Stationary Engine Driven Assemblies, UL 6200.
3 Glossary
3.1 For the purpose of this Standard, the following definitions apply.
3.2 STANDBY GENERATOR — Electrical generator intended to provide power during temporary conditions where normal power is disrupted (e.g. in the case of a severe storm).
4 General
4.1 Machines rated in excess of 1,000 V, or rated between 460 V and up to 34,000 V, and employing a form wound insulation system shall additionally meet the requirements of the Standard for Form Wound and Medium Voltage Rotating Electrical Machines, UL 1004-9.
5 Overspeed Test
5.1 The generator, arranged for operation in its intended manner, shall be subjected to an overspeed condition as described in 5.2.
5.2 The generator is to be operated at 120 percent of rated RPM and maintained at that speed for 1 minute.
5.3 There shall be no evidence of a risk of fire, shock, or personal injury as a result of this test.UL 1004-4 pdf download.