IEEE Std 3004.5 pdf free download
IEEE Std 3004.5 pdf free download.Application of Low-Voltage Circuit Breakers in Industrial and Commercial Power Systems.
Each one of these circuit breakers has different design characteristics and, in many cases, different application requirements.
NOTE—UL 1077 defines devices called supplementary protectors which provide some circuit breaker-like functions but are not circuit breakers within the context of applicable North American standards and hence are used to supplement other overcurrent protection within the guidelines prescribed by the National Electrical Code® (NEC®) (NFPA 70®) and UL 1077. This IEEE recommended practice does not cover supplementary protectors.2
MCCBs, as a class, are tested and rated in accordance with UL 489. Their current-carrying parts, mechanisms, and trip devices arc completely contained within a molded case of insulating material. MCCBs are available in the widest range of sizes, from the smallest (15 A or less) to the largest (6000 A), and with various interrupting ratings for each frame size. They are characterized generally by fast interruption short-circuit elements. Virtually all MCCBs interrupt fast enough to limit the amount of prospective fault current let-through, and some limit enough current and operate fast enough to be identified as current-limiting circuit breakers. The smaller continuous-current ratings are equipped with thermal-magnetic or magnetic-only trip units. Larger sizes are also available with thermal-magnetic or electronic trip units. With electronic trip units, they can have limited short-delay and ground-fault sensing capability. The cover and base of smaller MCCBs are designed so that the MCCBs cannot be opened for maintenance purposes. The main contacts of MCCBs cannot be removed however, some MCCBs are available with internal field-installable accessories. MCCBs are available in stationary or plug-in construction with circuit breaker enclosures that can be flush or surface mounted.
Within the MCCB classification there is another group of devices that is known within the industry as MCBs. The term miniature circuit breaker is notable because it is used to describe circuit breakers that are typically 1 in (25.4 mm) or less wide per pole and are commonly used in residential or lighting circuit applications at 120 V. 208 V, and 240 V. This type of circuit breaker often is provided with integral electronic ground fault or arc fault protection in addition to the thermal magnetic overcurrent protection. MCBs do not have a separate or unique designation within the UL 489 standard, and generally are tested as MCCBs per UL 489 requirements.LVPCBs are generally characterized by physically large frame sizes, drawout construction, and the highest short-time withstand ratings of all the types of low-voltage circuit breakers. They have short-time ratings, but they are not fast enough in interruption to qualify as current-limiting. They are rated and tested to satisfy the IEEE C37 series of standard requirements, and they are used primarily in drawout switchgear. When the circuit breaker is removed from its enclosure, the current-carrying parts and operating parts, depending on the design, may be partially or fully accessible for inspection, maintenance, and replacement purposes. Electromechanical trip units were used in the circuit breakers prior to the early 1970s. However, electronic trip units are used in new LVPCBs and are available as upgrades for older units.IEEE Std 3004.5 pdf download.
