Page 108 - CITS - Electronic Mechanic - TT - 2024

ELECTRONICS MECHANIC - CITS

WORKING:

When the AC supply current is flowing, it charges the batteries of the UPS. If this main supply is cut-off the
batteries of the UPS provided a DC voltage and then converted inside the UPS to an AC voltage, which is then
passed on to the load.
This makes sure that the load receives an uninterrupted supply of AC Power.
We use uninterruptible power supplies for equipment that must always remain switched ON, such as Mainframe
Computer, hospital equipment (e.g., life- support machines) and emergency lighting. We shall describe here the
working principle of online and offline UPS.

Different types of UPS :

1 Offline UPS (Standby UPS)
2 Online UPS (Double Conversion UPS)
3 Line-Interactive UPS
1 Offline UPS:

Offline UPS types are activated only when the main power is gone. In this type, the UPS is connected directly to
the consumer load. However, the offline type does not have an acceptable quality for the output power, and its
maximum power is limited.
Offline UPS Block Diagram:
Offline UPS device’s major components include a rectifier, inverter, battery bank, filter circuit, and critical load. A
single-phase or a three-phase input signal is provided as input to the rectifier.

In normal operating conditions, the current is drawn from the ac main power supply or grid, while the backup
source provides current in case of a power outage. Here battery is used as the backup source to deliver power
to the load in case of power failure.

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CITS : E & H - Electronics Mechanic - Lesson 56 - 63