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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
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