The UPS as an IoT node

The Internet of Things (IoT) is a collection of technologies that continues to grow rapidly because it gives us so much insight into, and control of, the world around us. It achieves this using remote sensors and actuators that communicate over local and wide area networks with powerful, cloud-based computing, storage and analytical resources that generate data-driven, timely decisions.

Uninterruptible power supplies, like other devices, benefit significantly if not critically from this online visibility. In particular, if they switch to back up battery power supply because of a mains aberration or outage, their critical load must be informed. This communication allows the load to shut down safely and automatically before suffering an unplanned power loss due to battery exhaustion.

However, while this is the most immediate and important uninterruptible power supplies communications function, there are other significant benefits of being online. Battery status, in particular, can be monitored and corrected, while other aspects of UPS power systems health become visible, and actionable, to remote managers and technicians in real time.

One practical point is that not all uninterruptible power supplies users want full two-way communications and control, because of security concerns if unauthorised individuals gain remote access to the UPS power systems. Such users prefer an uninterruptible power supply system that provides timely status information, then allows trained personnel to respond appropriately.

Different uninterruptible power supplies communications methods

UPS power systems communications options of varying degrees of sophistication are available to meet widely-ranging applications demands. The simplest setup comprises a dry port; volt-free contacts that communicate the uninterruptible power supply status to a remote monitoring station or local Building Management System (BMS) for integration with other building monitoring assets. Such schemes may also accommodate control signals to the UPS power supply, for example, remote shut-down commands issued as part of a sitewide emergency stop situation.

More detailed information can be communicated using point to point serial communications protocols such as RS232 or, for multidrop capability, RS485. As well as supporting emergency shutdown routines during a mains failure, simple on-screen monitoring of UPS power supply variables such as input voltage, current and battery status becomes possible.

Networking and Internet communications

However, to facilitate a full communications and control capability for a multi-module UPS power system serving a large data centre, Ethernet – and possibly Internet – network communication using TCP/IP protocol becomes essential. This uses an uninterruptible power supply management software application running on a server or Network Management Centre (NMC) communicating with matching software agents installed on the UPS power systems. Separate software agents handle shut down commands, UPS system surveillance and other software functions. The agents and central application must communicate using a common application layer protocol; the most popular are Modbus and Simple Network Management Protocol (SNMP).

An uninterruptible power supply with SNMP capability becomes an intelligent UPS power system that can, for example:

  • log events
  • continuously monitor power supply quality
  • report on UPS battery status, load and temperature
  • perform self-diagnostics

Intelligent uninterruptible power supplies may have the provisions for individually controlling the devices connected to it – for example, turning them off or on. This could enable the UPS system manager to isolate sections of the system for security purposes, shut down devices to save energy or manage redundant portions of the uninterruptible power supply system.

Remote UPS battery management example

One practical example of a remote UPS monitoring system, which can operate across Ethernet and Internet networks, is KUP’s PowerNSURE battery monitoring and management system. PowerNSURE checks the internal resistance, temperature and voltage of all the uninterruptible power supply batteries sequentially. The UPS power system implements battery equalisation, so extending UPS battery life, by correcting the charging voltage operating range. This prevents gassing, dry-out and thermal runaway.

The constant UPS monitoring and control of the individual charging voltages for each uninterruptible power supply battery guarantees its availability at all times. It also indicates UPS battery problems before power failure, allowing pre-emptive action to be taken. Additionally, temperature rises can be highlighted and acted upon before they lead to battery damage.

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