How to choose the UPS battery? The performance indicators of UPS
(1)Input voltage rangeInput voltage indicates the type of power supply to which the UPS is adapted. In addition to specifying whether the input AC voltage is single-phase or three-phase, the value of the input AC voltage, such as 220V, 380V, and 110V, should also be specified. At the same time, it should also give the adaptation range of UPS to the power grid voltage change, such as ±10%, ±15%, ±20%, ±35% on the basis of rated voltage. Of course, the phase number and input rated voltage can also be given separately in the product specification. The upper and lower limits of the UPS input voltage indicate that when the grid voltage exceeds the upper limit, the UPS disconnects the grid and the UPS battery start to supply power. The input voltage range of the backup and interactive UPS is 176 v to 264V. Table below lists the input voltage range of the online UPS.
(2)Input frequency rangeInput frequency range indicates the input AC frequency used by the UPS and the allowed change range. In mainland China, the standard value is 50Hz, and the input frequency range is 50Hz±1Hz, 50Hz±2Hz, 50Hz±3Hz, etc., which represents the synchronization range of the UPS internal synchronous phase-locked circuit. That is, when the grid frequency is within the range of change, the output of the UPS inverter is synchronized with the grid. When the frequency exceeds the range, the output of the inverter is not synchronized with the grid. The output frequency is determined by the 50Hz sine wave generator inside the UPS. The input frequency of the communication UPS ranges from 48-52Hz.
(3)Input power factor and harmonic component of input currentIn circuit principle, the power factor of linear circuit is usually expressed by cosφ, where φ is the angle of difference between sinusoidal voltage and sinusoidal current. For nonlinear circuits, although the input voltage is sine wave, the current may be non-sine wave, so the current distortion must be considered for nonlinear circuits. Generally defined as
PF=P/SWhere, PF is the power factor; P is active power; S is apparent power. In nonlinear circuits, if the ratio of fundamental wave current effective value to non-sinusoidal current effective value is defined as distortion factor, the current distortion factor D is Where, +… , represents 1,2… ,n times harmonic current effective value. If the phase difference between fundamental wave current and voltage is also assumed to be φ, the power factor PF can be expressed as: That is, the power factor of nonlinear circuit is the product of distortion factor and displacement factor (cosφ).The input power factor refers to the input power factor and the input current quality of the rectifier charger in the UPS. It indicates the capability of the power supply to absorb active power from the power grid and the interference to the power grid. The higher the input power factor is, the smaller the harmonic component content of the input current is, which indicates that the power supply has less pollution to the power grid. The input power factor of the online UPS meets the requirements of Table 1-2. And the harmonic components of the input current meet the requirements of Table 1-3.