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| Output capacity calculation method under Santak UPS power load |
| Time：2017-10-04 Source： Views：4213 |
Output capacity calculation method under Santak UPS power load:
First of all, when calculating the output capability of UPS under various loads, the varieties of UPS should be determined first, and the relevant data of the UPS shall be demanded from the manufacturer, and then calculated. But in this problem, the average UPS output can still maintain the rated capacity of 100% because the inductive load is less than the power factor under the rated condition. The data from a well-known Santak UPS power supply are taken for example. As shown in Table 1, when the inductive load power factor is less than 0.8 of the rated condition, the output power is still rated.
When UPS, cos, S=100kVA, phi, =0.8, P=80kW;
Q=60kVAR.
When UPS is S=100kVA and COS phi =0.6, then S=100kVA=60kW; Q=80kVAR.
If the load is 40kVA, cos phi =0.6, then S=40kVA;
P=24kW; Q=32kVAR.
When the load is increased to 80kVA, cos phi =0.6, then S=80kVA;
P=48kW; Q=64kVAR.
At this point, the apparent power S and the active power P of the load are less than the rated value, while the reactive power Q is greater than the rated value. However, the value of the load of COS phi =0.6 cannot be compared with the value of UPS at cos phi =0.8, but must be compared with the capacity of UPS for cos phi =0.6. The Q value of the load is less than UPS, and the Q value at this time is 80kVAR. Fully meet the load increased to 80kVA needs.
The problem of UPS with nonlinear loads. If UPS is 100kVA, cos phi =0.7, with nonlinear load Pentium 133PC+15in (inch) display (170VA) how many units can be taken? Cos phi =0.8 UPS and how many units?
There are many kinds of nonlinear loads, but many kinds of computer loads are rectifier capacitor filter type. Therefore, IEC, EN and GB (GB) have determined a baseline nonlinear load, which is diode full wave rectifier capacitor filter, the power factor is determined to be 0.7. UPS, that is, according to this standard. UPS also limits the peak factor of nonlinear current, typically 3. That is, the ratio of the peak value of the nonlinear current to the effective value is 3. This is also sufficient for computer loads. Because the peak factor is the maximum PC, about 2.7.
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UPS has the ability to carry nonlinear loads, except for a particular benchmark for nonlinear loads, and there is a quantity problem. 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 must be clear when we consider this question. But in this subject, none of the above points is a problem, and can be calculated according to the general linear load.
100kVA of UPScos phi =0.7, S=100kVA=70kW; Q=71.4kVAR.
When the single load is cos phi =0.7, S=170VA=119W; Q=121VAR.
For P and Q, the total number of UPS available is 588 units and 590 units.
Conclusion: according to the minimum calculation: 588 units (not leaving margin, start and so on).
How many units can you bring with 100kVA cos phi =0.8 UPS?
100kVA of UPScos phi =0.8, S=100kVA=80kW; Q=60kVAR.
When the load cos phi is still 0.7, the S=100kVA of UPS;
P=70kW; Q=71.4kVAR.
At this time, UPS can supply the total number of units to 588 units; 590 units.
Conclusion: it is also 588 units, and there is no difference between the two.
So, it seems that the power factor 0.7 UPS is no different from the UPS of the power factor 0.8. No, there's still a difference. The above examples are load power factor less than the rated value, if it is greater than the rated value, or capacitive load, the situation is not the same. The load carrying capacity of UPS with power factor of 0.7 appears to be poor.
A UPS with a power factor of 0.7 is only used for some microcomputer loads. It is designed to have a relatively small capacity, about 30kVA. The load power factor is 0.7, and the load power factor of UPS is designed to be 0.7, which is suitable for the load condition.
So, is this UPS powerful with nonlinear loads? No, on the contrary, its carrying capacity is worse than the 0.8 power factor UPS difference. The power factor of 1 10kVA is 0.8, UPS can carry 8kW power load, and the power factor of 0.7 UPS can only be brought to 7kW, such as power factor is greater than 0.7 of the load, its ability may be even smaller.
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