Detailed explanation of basic parameters of uninterruptible power supply system

UPS is the abbreviation of Uninterruptable Power System. It is divided into two types: dynamic and static. Dynamic UPS is composed of rotating motors, while UPS composed of electronic components is static. Generally speaking, UPS refers to static UPS.

UPS is mainly used in sensitive electronic equipment and places where power outages are not allowed, such as computer systems, process control of production lines, long-distance communications, medical equipment, airports, banking systems, etc.

Basic parameters of UPS

(1) Load Loads can be divided into three categories: 10 kV·A or less is a small load, 10 to 60 kV·A is a medium load, and 60 kV·A or more is a large load.

(2) Harmonic content (distortion) of the output voltage Harmonic voltage will cause noise to the reference voltage in the circuit and the logic circuit operating at low voltage.

(3) Non-linear load refers to inductive load or capacitive load. In computer systems, non-linear loads are mainly host computers, printers (especially laser printers) and display terminals, etc.; linear loads are mainly disk and tape devices. Generally, small loads are non-linear loads; medium loads are similar to linear and non-linear loads or one of them is slightly larger; and large loads are generally linear loads, because large loads are composed of multiple devices, which are up and down during operation, and the total load looks relatively stable in the macro sense. (4) Step load When a part of the load is connected or disconnected, the load will produce a step change. Since the UPS cannot instantly correct this sudden change in current, the output voltage will change accordingly. Small loads sometimes have a 100% step load because only a few devices are connected. The step load of medium loads does not exceed 50%. Large loads may only have a step load of more than 5% under abnormal operating conditions. General inverter designs can meet step loads of less than 25%.

(5) Efficiency For a large system, the efficiency must be high enough. For example, if a 125kV·A UPS has an efficiency of only 85%, the additional annual cost is equivalent to 30% of the initial investment.

(6) Size: Small and medium-sized UPS should be as small as possible.

(7) Noise The noise level of the UPS should not exceed the noise level required by the environment in which it is located.