Overview of the IEEE 141 Standard
Overview of IEEE 141 Standard
The IEEE standard 141 is periodically reviewed and revised by a committee called the Red Book Working Group or Red Book WG, since it is one of the electrical standards “color books”.
IEEE Std 141 was last updated in 1986. IEEE 141 has been adopted by the American National Standards Institute (ANSI) International and is also known as ANSI/IEEE 141.
What the IEEE 141 Standard Calls Out
IEEE 141 includes recommendations for regulating equipment voltage based on its load and general working conditions. IEEE 141 lists recommendations for installing surge protection and system protective devices to prevent electrical overload. IEEE 141 allows low voltage surge protection to be placed in a utility service drop or on service entrance equipment. Surge arrestors can be placed on the control panel. IEEE 141 advises against the use of motor-capacitor applications in motor starters due to the risk of capacitor overload.
Low voltage surge protection must be selected based on the surge protection requirements found using IEEE's recommended calculations. If there is not a surge protector rated for the calculated surge protection value, a better surge protector must be used. For example, if a 108 Volt surge protector is deemed necessary, 110V or 120V surge protector should be used, but a 100V surge protector is not considered good enough. Using a 200V surge protector in this same instance is also allowed, since it yields a much higher safety factor.
IEEE 141 recommends that lockout and tag-out procedures be used during maintenance and removal of motor control centers. Motor control centers should be turned off and electrically disconnected when under repair so that an accidental activation does not risk accidental electrocution of anyone working on it.
IEEE 141 gives recommendations of low voltage wiring insulation, such as those with relative heat resistance in hot manufacturing areas and moisture resistant cabling where the wires may be exposed to liquids or condensation. Electrical conductors can only be run outside if kept in a cable tray or conduit to protect it from exposure.
Electrical transformers may have dry, liquid or dual insulation. The letter associated with each type of insulation class increases with the temperature for which it is rated. Class B insulation is rated for 150°C while Class H is rated for 220°C.
IEEE initially released colored "books", each color pertaining to a specific set of power system design standards. IEEE 142 is the "Green Book" and addresses the grounding of industrial power grids and commercial power systems. The "Gray Book" contains IEEE Standard 241. This book addresses commercial building electrical power systems. The IEEE "Buff Book" gives recommendations for protecting and linking industrial and
commercial power systems. This standard was updated in 2001 and is separate from the IEEE's smart grid standards. The IEEE "Brown Book" describes recommended methods of analyzing industrial and commercial electrical systems. The "Orange Book" contains IEEE Standard 446 and covers emergency power supplies and standby power systems. IEEE Standard 493 is the "Gold Book". It gives IEEE's official recommendations on
improving the reliability of power systems. The "White Book" standard 602 addresses electrical systems used in health care facilities like hospitals and nursing homes where reliability and power quality must be high, since a power outage risks the lives of patients on ventilators and life support. IEEE Standard 551 is the "Violet Book", and it describes the recommended ways to calculating short circuit currents. IEEE Standard 1015 is the "Blue Book", separate from the "Kelly Blue Book" for car valuations.
The IEEE "Blue Book" discusses methods of installing and connecting low-voltage circuit breakers. The "Emerald Book" contains standard IEEE 1100. The "Emerald Book" is separate from the "Green Book" and was first published after the "Green Book". IEEE Standard 1100 addresses the powering and grounding of electronics and high-tech electronics.
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