An Easy Guide To Selecting UPS: Selection Methods

UPS Capacity Selection by kVA or by kW

When selecting a UPS capacity, the selection method differs depending on whether it is selected by kVA or by kW.


When selecting in kVA:

Select a UPS with a capacity that is greater than the total kVA of the load capacity (power consumption of the load equipment) and has a slight margin.

adding margin to total capacity when selecting UPS capacity

When selecting by kW:

Select a UPS with a capacity equal to or greater than the values in (1) and (2) below.


(1) Total value of [kW] of load capacity (power consumption of load equipment).

(2) The total value of [kW] divided by the load power factor and converted to [kVA].

UPS selection using kW capacity

When selecting in kW, the power factor of the load is the key.

The Type of Load Equipment

When selecting a UPS, it is necessary to check the load equipment.

(1) Equipment with large inrush current

For power system loads such as pumps and motors, check for inrush current.
(If there is an inrush current, the peak current value and flow time)

⇒It may be necessary to increase the capacity of the UPS in consideration of the inrush current.

Note 1) UPS cannot be used with power regeneration.

Note 2) If a large inrush current flows, it is necessary to check for problems.


(2) Medical equipment and highly public equipment

Special consideration must be given.


③Laser printers, facsimiles, copiers, etc.
It is not recommended to connect devices that regularly draw large currents.

Next: Input/output voltage of UPS