Networks Europe Issue 13 January/February 2018 - Page 44

44 UNINTERRUPTIBLE POWER SUPPLIES SNMP is vendor- and platform-independent, and establishes guidelines for how information is collected and managed. Network devices gather information into a management information base (MIB), from where it can be accessed by SNMP management software running within the user’s operating system. An SNMP-enabled UPS is an intelligent device that can log events, continuously monitor power quality, report on battery status, load and temperature, and perform self- diagnostics – but this built-in intelligence creates other management opportunities as well. The UPS can handle incoming commands to control the individual devices it supplies; for example, to isolate sections of a system for security purposes, shut down some devices to save power, and manage redundancy. Predictive maintenance also becomes possible. The UPS can log power disturbances, track battery usage, alert managers to low battery problems, and track power level history. Through SNMP, this information is available across the network for immediate analysis and to detect potential problems before they cause downtime or damage. SNMP- based networking can also be expanded to encompass multiple UPSs for optimum efficiency in load management. Information can be collected from, say, several dozen UPSs into a central network console to allow an integrated, large- scale control strategy. The monitoring software is available for most operating systems, and its facilities may include: • A graphical display of UPS status, voltage, current, load, battery voltage and frequency and more • Configurable responses to certain alarms, which can include broadcasts to users • Scheduled diagnostic checks and data logging RS-485 or full-duplex RS-422 communications can be used for longer distances, and modern UPS equipment also provides a USB port. Modbus, an application-layer serial communications protocol that operates over either RS-485 or IP links, can also be used to communicate with up to 240 devices across a common network. Network-based solutions Larger systems spread over wide areas across sites that may be hundreds or even thousands of miles apart, present monitoring, management and maintenance challenges that can only be addressed with a full IP-based Wide Area Network (WAN) solution. This is especially true if some of the sites within the network are unmanned, or without a network manager. Any problems they experience could cause irreparable damage to system hardware and software without a means for rapid resolution. The solution is to equip devices like UPSs with Simple Network Management Protocol (SNMP) capabilities, as this allows monitoring and control of every device on a WAN from a central location. SNMP is a standard protocol and part of the Transmission Control Protocol/Internet Protocol (TCP/IP) suite which allows all network devices to transmit management variables across enterprise-wide networks. Fig.2: Remote UPS monitoring facility All UPSs need some type of communications capability, to warn their critical load of a power failure. For some simple systems, that’s all that’s necessary, but larger, distributed and multi-site systems can benefit from more sophisticated network solutions. As well as immediate warnings, these allow predictive maintenance, strategic analysis, early intervention from remote or third-party specialists, and advanced, centralised control strategies of large, multi-UPS systems from centralised management consoles. n