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1 OF 2 <br />GENprotect ™ <br />Seamless Protection for Industrial Power Generators <br />Doc. No 0187980SBY <br />Rev. D 06/13/19 GENERATOR CONTROLSGENprotect Operation <br />The design choice of an onsite power system using a Generac <br />Industrial Power Generator assures your emergency power source <br />is protected from unexpected power distribution faults. Typically, <br />a generator will include some type of over-current device, such <br />as a circuit breaker, or be protected by inherent design with the <br />controller protecting the alternator through a protection algorithm. <br />Generac’s GENprotect generator protection system monitors the <br />system current output and protects the alternator with extended <br />security against fault scenarios that could occur within the site’s <br />downstream distribution system. <br />It is a common misconception that the alternator’s main circuit <br />breaker protects the alternator from a short circuit event. The main <br />output breaker protects the cabling and provides a convenient <br />disconnect. The characteristic trip curve for the industry standard <br />thermal magnetic breaker (MCCB, molded case thermal magnetic <br />or solid state) does not coordinate with the thermal damage <br />limitation for an on-site generator. If circuit breakers are used <br />for generator protection, a solid-state circuit breaker with full <br />adjustments (Long Time, Short Time and Instantaneous, LSI) <br />is required to coordinate the breaker protection curve within <br />the generator thermal damage curve. Historically, this limitation <br />was often accepted in system design since failures of the main <br />generator feeder are extremely rare. Most short circuit events <br />happen at a branch circuit, equipment level, where the fault is easily <br />cleared by the smaller down stream breakers. <br />Given the mission critical nature of today’s back-up power <br />applications, it is more desirable to protect the system against even <br />relatively rare failure modes. As generator controllers have become <br />more powerful it is feasible for manufactures to supply coordinated <br />short circuit protection integral to the generator control system, <br />negating the need for a main-line circuit breaker. <br />Generac’s GENprotect alternator protection algorithm monitors <br />the generator output. If this monitoring senses short circuit <br />current in excess of rated amps, GENprotect steps in to provide a <br />controlled and safe approach to breaker coordination and alternator <br />protection. GENprotect first limits the alternator short circuit current <br />level to 300%. By limiting the available fault current, GENprotect <br />extends the time the alternator can maintain fault current resulting <br />in consistent breaker coordination. Without this functionality a <br />line to neutral fault may be at 800% of rated current and need to <br />be cleared within 1.4 seconds. The second function GENprotect <br />performs is I2T thermal protection for the alternator. Since a short <br />circuit event can heat the alternator so rapidly, it is not possible <br />to protect the alternator by monitoring temperature. Instead <br />GENprotect calculates the heat energy of the fault current. When <br />this energy reaches the limits of NEMA MG1, GENprotect trips <br />the generator off-line. This configuration ensures the alternator is <br />protected and the power system is ensured 10 seconds of 300% <br />fault current for breaker coordination. <br />DESCRIPTION <br />•GENprotect is an alternator protection algorithm approved by UL. <br />•Protects alternator from damage due to shorts and electrical faults. <br />•Provides breaker coordination and alternator protection. <br />•Allows for use of multiple circuit breaker choices, including <br />“no” breaker. <br />Docusign Envelope ID: 2F58BEE5-DDBE-42EB-8DFA-5E2508488B04