Siemens' New Uninterruptible Power Supply with Maintenance-Free Capacitors Saves Batteries
Siemens' Industry Automation Division has equipped its new uninterruptible 24-volt Sitop UPS500S power supply for direct voltage systems with an innovative, maintenance-free capacitor system. This new energy store contains high-capacity, double-layer capacitors and has a long service life, even where ambient temperatures reach 140 degrees Fahrenheit. That is a big advantage over conventional lead-acid batteries that have to be replaced every year where temperatures are just 104 degrees. Moreover, the place of use no longer needs to be expensively ventilated, as capacitors do not emit explosive hydrogen gas. Depending on needs and the expansion stage, when a power failure occurs, the new 15-ampere Sitop units guarantee the continued operation of 24-volt loads – such as industrial PCs and numerical and programmable logic controls – for up to several minutes.
The basic Sitop UPS500S unit is 4.7 inches wide. Its capacitors can store either 2.5 or 5 kilowatt seconds of energy and deliver an output current of up to 15 amperes, thus converting a 24-volt power supply unit into an uninterruptible power supply unit (UPS). Simply plugging 2.7 inch wide, 5 kilowatt expansion modules into the basic unit lengthens the buffer time. This ranges from a few seconds to several minutes, according to the desired load current and configuration. This provides sufficient time to back up important data or ramp down a terminal device in a controlled manner – depending on the application. The desired buffer time is set with DIP switches. These new 24-volt UPS units are characterized by a short recharging time, which quickly restores the buffering capability after a power failure. It only takes a few minutes to recharge the capacitors, in comparison to the hours required for lead-acid batteries.
Sitop UPS500S can be used in ambient temperatures up to 140 degrees without any maintenance expenditure. For example, the energy storage capacity falls by only 20 percent over eight years at an ambient temperature of 122 degrees. This is a big advantage over lead-acid batteries whose capacity at a cabinet temperature of just 104 degrees dwindles steadily to such an extent that they have to be replaced every year. The basic module has relay contacts and a USB interface for outputting status messages. There is a software tool available for download from www.siemens.com/sitop for further processing status messages on a PC. These new Sitop power supplies have been tested and harmonized with the Simatic PC system. This ensures that these units are not only ramped down under control, but also restarted correctly in all situations. For trouble-free 24-hour operation of PC applications, there is, for example, a system tested combination of new uninterruptible power supplies and the Simatic PC Microbox.
The new Sitop UPS500S units offer IP20 protection and are designed as standard mounting rail modules for mounting in control cabinets. Versions with the higher degree of protection IP65 for distributed use in tough environments are under development. These units will supply a 7 ampere output current and be fitted with 5 or 10 kilowatt second capacitor energy storage.
