First, when calculating the output power of Santak UPS power supply under various loads, we should first determine the variety of UPS, ask the manufacturer for the relevant data of UPS, and then calculate. But in this problem, because the inductive load is less than the rated power factor, the general UPS output can still maintain a rated capacity of 100%. Now use a famous Shenzhen Santak UPS power supply data as an example to calculate. Table 1 shows that inductive load power factor is less than the rated case of 0.8, the output power is still rated.
When UPS S=100kVA, COS with =0.8, P=80kW;
Q=60kVAR.
When UPS is S=100kVA, cos is =0.6, S=100kVA=60kW; Q=80kVAR.
If the load is 40kVA, cos =0.6, S=40kVA;
Q=32kVAR; P=24kW.
The load was increased to 80kVA, cos =0.6, S=80kVA;
Q=64kVAR; P=48kW.
At this time the apparent power S and active power P are less than the rated value, but the reactive power Q is greater than the rated value. However, numerical cos cannot be used with =0.6 load numerical and COS phi =0.8 UPS when compared to UPS and COS to =0.6 when the ability is better than. The Q value of the load is less than UPS Q value at this time 80kVAR. Fully meet the load to 80kVA needs.
Santak UPS with nonlinear load problem. If UPS is 100kVA, cos is =0.7 with a nonlinear load Pentium 133PC+15in (inch) display (170VA) can take a number? COS with =0.8 UPS and with the number of Taiwan?
Nonlinear load is multifarious, but computer load is mostly rectifier capacitor filter type. So IEC, EN and GB (GB) have identified a benchmark nonlinear load, diode full wave rectifier capacitor filter, power factor is determined to 0.7. UPS is made according to this standard. UPS also defines the peak factor of the nonlinear current, typically 3. That is, the ratio of the peak value to the effective value of the nonlinear current is 3. This is enough for computer load. Because the peak factor is the largest PC machine, about 2.7.
UPS with nonlinear load capacity, in addition to nonlinear load specific benchmarks, there is a problem of quantity. In IEC, EN and GB (GB) clearly stipulates: single-phase UPS capacity in 33kVA, with reference to the nonlinear load assessment, more than 33kVA UPS 33kVA with nonlinear load and linear load assessment; three-phase UPS capacity below 100kVA, with reference to the examination of the nonlinear load, more than 100kVA UPS the benchmark nonlinear 100kVA load and linear load assessment.
The above points are necessary when we consider this problem. But in this topic, these points are not a problem, can be calculated according to the general linear load situation.
UPScos with =0.7 100kVA, S=100kVA=70kW Q=71.4kVAR.
A single load COS with =0.7, S=170VA=119W; Q=121VAR.
For P and Q, UPS for the total number of units are as follows: 588 Taiwan 590 Taiwan.
Conclusion: according to the minimum calculation: 588 units (no allowance left margin, start and other factors).
If you use 100kVA COS with =0.8 UPS band number?
UPScos with =0.8 100kVA, S=100kVA=80kW Q=60kVAR.
When the load is still 0.7 cos, UPS S=100kVA;
Q=71.4kVAR; P=70kW.
The UPS for total units were 588 units, 590 units.
Conclusion: also 588, the two no difference.
So, it seems that power factor 0.7 UPS and power factor of 0.8 UPS no difference. No, there's a difference. The above examples are the load power factor is less than the rated value, if greater than the rated value, or capacitive load, the situation is not the same. Power factor of 0.7 UPS carrying capacity is poor.
Load power factor of 0.7 UPS is only used for some microcomputer load. Its design capacity is relatively small, about 30kVA below. And this kind of load power factor is 0.7, UPS load power factor is also designed to be 0.7, just to adapt to the load conditions.
So this UPS is not the ability to load with nonlinear it is not, on the contrary, its carrying capacity than the 0.8 power factor UPS difference. 1 10kVA power factor of 0.8 UPS can bring 8kW power load, while the power factor of UPS can only be brought to 7kW, such as the power factor greater than 0.7 of the load, the capacity may be smaller.