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Spotlight

Introducing 3rd Generation UPS

Wed, 01/25/2012 - 08:42

An uninterruptible power source, or uninterruptible power supply (UPS), is a piece of equipment that provides emergency power to systems when the regular power source fails. A UPS differs from a standby generator in that it provides instantaneous power, which can be particularly useful in situations where sensitive equipment needs time to correctly shutdown in case of a total power failure. Common applications include computers, data centres, telecommunication and other electrical equipment, where incorrect or unexpected shutdown could cause injuries, business disruption or data loss. UPSs achieve instantaneous power either through attached batteries in low power applications, or through the use of a generator or flywheel for higher power applications.

The latest generations of UPS devices aim to reduce the energy needed to run. As well as having the traditional ‘double conversion’ operating mode common to most UPS devices, these third generation units also have two other modes of operation that move operating efficiency from 95% to up to 98% efficiency, while still maintaining the same high levels of AC power protection. It seems from early tests that these devices can reduce the cost of cooling a UPS by as much as 400%.

Another development in UPS technology is the change of power systems used for situations when a UPS will have to be used for hours rather than minutes. In these cases, UPSs are being built that contain hydrogen fuel cells, which use a virtually inert water and ethanol fuel mix that is converted to hydrogen, which is subsequently used by the fuel cell to generate electricity. The use of these hydrogen fuel cells requires a traditional UPS to provide backup while the hydrogen reaction begins, but the ethanol water fuel store allows these next generation devices to operate for lengths of more than 24 hours.

New technologies for energy storage are being developed that represent an alternative to batteries as an energy source for the UPS. One of them is the flywheel technology, which consists of a rotating mechanical tool that stores energy resulting from its movement when it is connected to an electric system. Once the power system is shut down, the flywheel’s kinetic energy is converted to electrical energy that the UPS can use. Flywheels are an environmentally friendly alternative to batteries, and unlike most batteries, are able to function at temperatures from 0°C to 40°C. However, one of the disadvantages of these new types of UPS is the cost, which is much higher than for UPSs that utilize conventional energy sources.

UPS devices are particularly useful for the oil and gas industry in remote locations such as oil platforms, as they guarantee access to electricity in emergency situations. Pemex norms require offshore platforms to have separate UPSs for different systems, such as the monitoring of processes, emergency stoppage, gas and fire, emergency lighting and the telecommunications system. Also, instruments sensitive to energy fluctuations or disturbances should be connected to a UPS. Pemex also requires that all UPSs used offshore are capable of transferring electricity without any interruption and are equipped with pulse- width-modulation (PWM) technology.

The Deepwater Horizon incident shed light on how UPS systems were being used on board the drilling platform. One UPS was used for backing up power to the drilling control system located on the rig; another two were for providing emergency power to the blowout preventer, and one was used to power a redundant fire and gas emergency system. There were five redundant IACS UPS systems onboard, eight redundant thruster UPS systems, two redundant hydroacoustic reference system (HPR/ HIPAP) UPS systems, and two public address/general alarm UPS systems. All of these were designed to function for no less than 18 hours. All of these systems worked perfectly during the incident, it was reported.