The OFFLINE UPS supplies the incoming mains supply directly through to the output usually through a relay contact. Some high frequency noise filtering and surge suppression may be included in this path.The UPS swiches on its inverter as soon as mains supply failure is detected or below the normal load and simultaneously switches the output relay to the inverter side to supply battery sourced power to the load. This transition involves a delay on account of the time to reliably detect mains failure and switch over a relay, and the output is broken for this period (usually for 2 to 12msec).
Important Features for 1250VA Metal Case Offline UPS from TRM are ►Wide input voltage range ►AVR function ►Cold start function ►Intelligent CPU control ►Both audible and lamp alarm functions ►Intelligent battery management.
UPS Selection Guide
►Decide the required size of the UPS (VA & Watts) to decide Power Capacity of the required UPS, you should decide which consumers should be protected and its power consumption in Amps, VA, or Watt.
►Decide the required Autonomy time (Back-up time) Autonomy time is the time that batteries are able to back-up operation and feed the load upon failure of utility power. Load consumption and size of UPS batteries dictate the back-up time.
►Decide the type of the UPS you need UPS's are roughly divided to three main classes. The Off Line (Stand-by) UPS is the simplest and the least expensive, then comes the Line Interactive type, which overcomes the major disadvantages inherent to the off-line unit, finally the Double Conversion On-Line UPS which provides the best power protection.
►Refine the deal at these stage you should already know the KVA rating of the UPS you intend to buy, the type of the UPS (Standby/Line Interactive/On-Line), the autonomy time needed, and the configuration (Stand alone or Redundant).
Tips to help you while concluding your Power UPS deal
►Increase UPS capacity to allow for future expansion.
►Don't buy back up time that you don't need. Longer backup time does not mean better UPS.
►In case of Online units make sure you can add external batteries in future and that you can increase power by adding parallel units if expected.
►Don't buy any extras if you are not sure that they are needed for your application, Most can be added in the future whenever required.
►Make sure that the UPS performs automatic battery tests, warning whenever the batteries should be replaced.
►Backup time has no meaning if you don't consider the amount of UPS loading. Partial load increases the time the battery backs-up the equipment.