Uninteruptible power supplies UPS

Industrial uninteruptible three-phase backup system

It is a backup solution of the type „online double conversion on-line UPS“. Power range is between 4kW and 250 kW, limited time overload of 2x of rated current, or even higher if requested.

Two energy conversions:

• 1. rectification from input AC grid to DC voltage for battery charging,
• 2. inverting the DC voltage to the output AC voltage of requested parameters (voltage, frequency) for the proper supply of the loads

Pros:

• custom made solution, according to the requirements of the customer
• any grid failure (overvoltage, undervoltage, short circuit ) will not cause a downtime for backed up devices
• guaranteed supply voltage quality, very low voltage THD
• sine shaped grid current, THDi <3%
• adjustable grid-side power factor setting (0.9 inductive ÷ 0.9 capacitive)

Cons:

• higher price when compared to paralel conenction below
• it is required to properly design the device for all the peak and inrush currents

Paralel three-phase backup system, short time outage possible

This is a backup supply very similar to the type „The Line Interactive UPS“. Power range is between 4kW and 250 kW, limited time overload of 2x of rated current, or even higher if requested.

One energy conversion only:

• 1. charging is done from the input AC grid to the DC battery, in case of grid fault the energy flow direction is immediately inverted (and the grid disconnected).

Pros:

• custom made solution, according to the requirements of the customer
• guaranteed supply voltage quality, very low voltage THD
• sine shaped battery charging current, THDi < 3%
• adjustable battery charging power factor setting (-0.9 inductive ÷ -0.9 capacitive)
• energy peak-shaving, it can serve as a power controlled AC generator
• made to survive short-term inrush currents
• lower prace and higher overall efficiency when compared to uninteruptible serial connection of power supply

Cons:

• few kinds of grid fault (short-circuit, surges) can cause a short outage of the supply (far shorter than 1s)

Proper termination of the operation

Uninteruptible power supplies (UPS) are used for applications which require operation safety and comfort – finishing the working cycle during power supply drop-out, f.e. by elevators, casting production line, electro-wagons etc.