UPS is used to provide good quality and steady voltage to the computer instrument and it peripheral in presence and absence main power supply for the particular duration of time. It consists of a transformer device, an inverter system and a battery set up. It protects the workstation system in opposition to unexpected changes in power which can damage software and hardware of the computer system.
UPS devices are classified by IEC-62040-3
The UPS protects the computer system from the following type of effects which may create failure due to the irregularity of power supply:
a) Spikes: The sudden and brief surges of very high voltage can cause irreparable damage to the computer system.
b) Blackouts and Brownout: The total loss of the power supply is called blackout and a short drop in the power supply is called brownout.While blackout can cause loss of data in RAM and at times corrupt hard drives and brownout usually result in frozen keyboards and system crashes.
c) Fluctuation: The variation in voltage and current of the main power supply is called fluctuation it can damage the fine soldering on the motherboard and other components of the computer system. Fluctuations include voltage and frequency effects.
The power line disturbance which we observed are power outage, lightning effect, voltage surge and harmonics
UPS can be classified into the following three categories
1. Online UPS or Double Conversion UPS
In online UPS, the power for the system is supplied by the battery, which in turn is powered by the mains. This kind of UPS blocks all type interruptions in the stream of power moreover it uses more electronic circuits compared to offline UPS, it demands a higher price. Besides higher prices, online UPS as well include the drawback of high operating expenses and high temperature. Because the battery acts as a main current supply to the structure. An online UPS battery charger has to be capable enough to generate sufficient power to balance the battery power drain.
The transfer from AC mains to DC used for the battery along with reverse to AC by the inverter results in a 25 to 30 percent loss of a mere 1 to 2 percent. which means a longer lifespan
2. Off-line UPS or Passive Standby UPS
An off-line UPS provides an alternative source of power in the case of a power failure of fluctuation, By default power is supplied directly from the mains to the system , any drop in the electric potential or current is detected by the UPS it automatically come in line by switching the battery into the circuit, switching off the main power line, which make power from the battery to supply all the required power.
Ideally, the change over should not take more than 4-5 milliseconds, this is important for computer power control units, If it does not happen within this time frame, the system detects the change in power condition and reboots.
3. Line Interactive UPS