What is UPS?
An uninterruptible power supply ,UPS or battery/flywheel backup, is an electrical apparatus that provides emergency power to a load when the input power source, typically mains power, fails. A UPS differs from an auxiliary or emergency power system or standby generator in that it will provide near-instantaneous protection from input power interruptions, by supplying energy stored in batteries or a flywheel. The on-battery runtime of most uninterruptible power sources is relatively short (only a few minutes) but sufficient to start a standby power source or properly shut down the protected equipment.
There are different types of UPS such as
1. On line UPS
2. OFF line UPS
3. Line interactive UPS.
What is Online UPS?
In an online UPS, the batteries are always connected to the inverter, so that no power transfer switches are necessary. When power loss occurs, the rectifier simply drops out of the circuit and the batteries keep the power steady and unchanged. When power is restored, the rectifier resumes carrying most of the load and begins charging the batteries, though the charging current may be limited to prevent the high-power rectifier from overheating the batteries and boiling off the electrolyte.
The main advantage to the on-line UPS is its ability to provide an electrical firewall between the incoming utility power and sensitive electronic equipment.
What is Offline UPS?
In Off line UPS The protected equipment is normally connected directly to incoming utility power. When the incoming voltage falls below a predetermined level then UPS turns on its internal DC-AC inverter circuitry, which is powered from an internal storage battery. The SPS then mechanically switches the connected equipment on to its DC-AC inverter output. The switchover time can be as long as 10 milliseconds depending on the amount of time it takes the standby UPS to detect the lost utility voltage. The UPS will be designed to power certain equipment, such as a personal computer, without any objectionable dip or brownout to that device.
Off Line UPS the load is connected directly to the mains when main supply is available and it is not too high or not to low. When the over voltage or under voltage conditions are detected on the mains The UPS transfer the load to the inverter. When the line is present, the battery charges through the rectifier. Thus in Off-Line UPS There is a load Transfer involved every time the mains is interrupted and restored.
WLine interactive UPS:-
Line-interactive UPS. Typical protection time: 5–30 minutes. Capacity expansion: Several hours The line-interactive UPS is similar in operation to a standby UPS, but with the addition of a multi-tap variable-voltage autotransformer. This is a special type of transformer that can add or subtract powered coils of wire, thereby increasing or decreasing the magnetic field and the output voltage of the transformer. This is also known as a Buck–boost transformer.