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4. UPS DESCRIPTION
The purpose of this UPS is to ensure a perfect supply voltage for the devices connected to it, whether main
power is present or not. After connection and power up, the UPS generates a sinusoidal alternating voltage
with stable amplitude and frequency, regardless of any sudden change or variation in the main supply. The UPS
draws energy from the mains and charges the batteries, controlled by a multi-processor board. This board
continuously monitors the amplitude and frequency of the main voltage, the amplitude and frequency of the
voltage generated by the inverter, the load applied, the internal temperature and the state of battery efficiency.
The UPS block diagram shown here with a description of its individual components.
Important:
The UPS is designed and built for durability, even under the most stringent
operating conditions.
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5. OPERATION
5.1 Operation Modes
The UPS is a double-conversion online UPS that may operate in the following alternative modes:
• Normal Mode
The rectifier/charger derives power from the AC mains and supplies DC power to the inverter while
floating and charging the battery simultaneously. The inverter converts the DC power to AC and
supplies to the load.
• Battery Mode (Stored Energy Mode)
If the AC mains input power fails, the inverter obtains power from the battery, supplies the critical
AC load. There is no power interruption to the critical load. The UPS will automatically return to
Normal Mode when AC recovers.
• Bypass Mode
If the inverter is out of order, or if overload occurs, the static transfer switch will be activated to
transfer the load from the inverter supply to Bypass supply without interrupting the critical load.
In the event, that the inverter output is not synchronized with the Bypass AC source, the static switch
will perform a transfer of the load from the inverter to the Bypass with power interruption to the
critical AC load. This is to avoid paralleling of unsynchronized AC sources. This interruption is
programmable but typically set to be less than an electrical cycle e.g. less than 15ms (50Hz) or less
than 13.33ms (60Hz).
• ECO Mode
When the UPS is in AC Mode and the requirement to the load is not critical, the UPS can be set at
ECO mode in order to increase the efficiency of the power supplied. At ECO mode, the UPS works at
line-interactive mode, so the UPS will transfer to bypass supply. When the AC is out of set window,
the UPS will transfer from bypass to inverter and supply power from the battery. The LCD shows all
related information on the screen.
• Parallel Redundancy Mode (System Expansion)
To achieve a higher capacity and/or increase reliability, the outputs of up to 4 UPS' can be
programmed to operate in parallel and the built-in parallel controller in each UPS ensures
automatic load sharing.
• Maintenance Mode (Manual Bypass)
A manual Bypass switch is available to ensure continuity of supply to the critical load when the UPS
is out of order or in repair and this manual bypass switch bears for equivalent rated load.
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