Specifications include, but are not limited to: This specification describes the minimum requirements for a Battery Backup System (BBU) for Traffic Signal. The BBU System consists of three modules within an enclosed cabinet: Inverter/Charger Bypass Switch Battery Bank OPERATING REQUIREMENTS A. The BBU System shall be certified per UL 1778. All elements of the System shall comply with the applicable code sections of the NEC, NEMA, and OSHA. B. The BBU System shall operate using the Line Interactive (Buck and Boost) method. C. The BBU System shall be capable of operating a signalized intersection (700- watt load) for four hours of full runtime when utility power is disabled and under ambient temperatures of 25°C. D. The BBU system shall switch the intersection to flash mode of operation when approximately 40% of battery charge is remaining via relay contact connection points on the front panel of the inverter/charger unit. The BBU System shall operate the intersection in the flash mode of operation (350-watt load) for an additional two hours. E. The transfer time allowed, from disruption of normal utility line voltage to stabilized inverter line voltage from batteries, shall be less than 65 milliseconds. The same allowable transfer time shall also apply when switching from inverter line voltage to utility line voltage. F. The BBU system shall bypass utility line power whenever the utility line voltage is outside of the manufacturer’s default or a user programmed voltage range ±2V AC. G. When the utility line power has been restored to a normal operating voltage for more than 30 seconds, the BBU system shall transfer from battery back to utility line mode. The BBU shall be equipped to prevent a malfunction feedback to the cabinet or from feeding back to the utility service. H. The BBU system shall operate with an automatic “fail safe” mode. Should a breaker trip on the inverter/charger and/or the power transfer relay, the unit will automatically default to utility line power and bypass the BBU system. I. The BBU system unit shall be capable of logging up to 100 events. Events shall date and time stamp faults with AC line voltage and BBU battery voltages. The following conditions shall be recorded as an event: 1. Occurrences of the utility line voltage being above or below the upper and lower control limits or manufacturer preset defaults. 2. Whenever the BBU system automatically switches to battery power. 3. Self-monitoring, BBU system component failures shall be recorded as an event.
