Page 218 - Electrician - TT (Volume 2)

ELECTRICIAN - CITS

Fig 4

Fig 5 Fig 6

Fig 7

Often it is found that the battery is in discharge mode even when mains is present i.e the battery shares the load
current with the mains. This happens when the mains voltage is low and/or the output is loaded to above 75%.
The efficiency of ON line UPS can be increased by using boost type power factor correction circuit.

Advantages
• Constant output voltage (No AVR card) free from changeover problem.
• Constant charging current.
Disadvantages

• complex in design, lower efficiency, higher cost, bigger in size and strain on the battery.

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CITS : Power - Electrician & Wireman - Lesson 93-100 CITS : Power - Electrician & Wireman - Lesson 93-100