1. ON-LINE method
A method of supplying power in an uninterrupted manner in an emergency by receiving normal AC input power, charging the built-in battery and operating the inverter at all times. It is mainly applied to medium to large-sized UPS, and is used in cases where high-quality power is required, such as power supply for large computer rooms and factory automation. It is used in equipment that requires frequency, and this method is mainly used for capacities over 3KVA.
Advantages: a) Since it is non-stop (no interruption) in the event of an input power outage, it supplies stable power regardless of the input.
B) Supply quality power according to the circuit configuration.
c) Provides a constant output voltage regardless of changes in input voltage. (Automatic voltage adjustment: AVR function)
d) Supply output power by blocking input surges and noise.
E) It has a built-in protection circuit against output short-circuit (SHORT), overload (OVER LOAD), etc.
f) The output voltage can be adjusted within a certain range (±10%).
Disadvantages: a) The circuit configuration is complex, so technical skills are required.
B) Efficiency is lower than OFF-LINE (higher power consumption)
c) The appearance and weight are large.
d) It is generally expensive. 2. OFF-LINE method
This method uses AC input power under normal conditions, but uses an inverter (UPS) when there is a power outage or the input power is lower than the allowable level.
This method was used for small and medium capacity before UPS became popular, and is currently mainly used for small capacity UPS.
Advantages: a) High efficiency when input power is normal (low power consumption)
B) The circuit configuration is simple, so durability is high (less minor breakdowns).
c) The price is cheaper than ON-LINE
D) Miniaturization is possible
E) During normal operation (commercial input), there is little electromagnetic waves (including noise) generated.
Disadvantages: a) A momentary power cut occurs during a power outage. (No problem in general PCs: condenser INPUT type power supply)
B) The output changes depending on the input change. (Voltage adjustment is not possible)
c) It is not suitable for precision loads as it is not synchronized with the input power.
3. LINE INTERACTIVE method
When the input power is normal, it is a method with a built-in automatic voltage adjustment function (mainly using 4 taps) to keep the output voltage constant. It is a technology intermediate between the ON-LINE and OFF-LINE methods and complements the pros and cons. Currently, it is mainly used for small-capacity UPS.
Advantages: a) High efficiency when input power is normal (low power consumption)
B) Circuit configuration is simpler than ON-LINE.
c) The price is cheaper than ON-LINE
d) It has an automatic voltage adjustment function.
Disadvantages: a) Durability is lower than OFF-LINE.
B) There is a risk of overcharging and the frequency of breakdown of the charging part is high.
(Because it charges with a voltage stability of about 5% of the input power) |
