To select the capacitor for a certain load, then we need to know the capacity (P) of the load and power factor (Cos φ) of the load:
Suppose we have a load capacity of P
Power factor of load is Cos φ1 → tg φ1 (before compensation)
Power factor after compensation was Cos φ2 → tg φ2.
Capacity to compensate the protesters QC = P (tgφ1 - tgφ2).
From the capacity to compensate capacitor is chosen to match the table catalog provider capacitor.
To understand we will give examples as follows:
Suppose we have the capacity load of P = 270 (KW).
Power factor before compensation is cosφ1 = 0.75 → tgφ1 = 0.88
Power factor after compensation is Cosφ2 = 0.95 → tgφ2 = 0:33
So the capacity to compensate the protesters Qbu = P (tgφ1 - tgφ2)
Qbu = 270 (0.88 - 0:33) = 148.5 (KVAr)
From this figure we choose the capacitor manufacturer's catalog table assumes that capacitors have 25KVAr. Enough to compensate for the load we need to make up 6 from 25 KVAr total capacity of protests is 6x25 = 150 (KVAr) with 6 of this capacitor is chosen as the controller 6-map drawings:
Optimization Method Based Clearing Conditions Not Close Penalty:
- Considering electric bills related to the capacity kVArh consumed and recorded some kVArh pay later, select bills kVArh highest price paid (not consider exceptions).
For example kVArh 15,965 in January
Calculated the total operation time in the example 220h hours are now considered to calculate the electrical system bear the greatest load and peak load value added. outside time since the consumption capacity of protests is free.
- The value of capacity to compensate:
[kVAr] = Qbu. kVAr: kVAr of pay.
T: number of hours of operation
- Capacity compensation is often higher than the selected value calculations a bit.
- Some airlines offer size loga rules designed especially for these calculations under the separate brackets. Tools and the data is included to compensate for equipment selection and appropriate control scheme, and binding of voltage harmonics in power system. harmonics require the use of the residual convergence (related to cooling, the voltage and current levels) and coil resistance or circuit to filter harmonics.
Why should improve power factor:
1. Off the money supply:
- Raising power factor to bring them the advantages of technical and economic power of money is reduced.
- During the period electricity use is limited by regulations. The energy consumption protests exceed 40% of the energy effects (tgφ> 0.4: this is the agreement with the company supplying electricity) is the use of energy protesting pay monthly rates current.
- Therefore, the total energy protesters were charged for time used will be:
kVAr (pay) = kWh (tgφ - 0.4)
- Although the benefits of reduced electricity cost, the user should consider factors affecting the cost of procurement, installation maintenance of capacitors to improve power factor.
2. Optimize economic - technical
- Improving power factor allows users transformers, switches and cable equipment under VV .. while reducing power loss and drop in the electrical network.
Power optimization allows high elements provide electricity. Then the electrical equipment does not need the excess amount. However, to achieve the best results, it should be placed next to each element edge convergence of devices consume capacity protests.
- Improve power factor
+ To improve the power factor of the electricity network, to a capacitor to source capacity protests. How to solve this is called compensation capacity protests.
+ Download with emotional power factor is low will become the current protests from generators to the transmission system to deliver. Thus pulling the loss of productivity and drop phenomenon.
+ When infected in parallel with the capacitor load, current use of a computer will have the same convergence path as part of the line feel resistance load. so the current will then eliminates mutual IC = IL. Such lines do not exist protests over the net forward placement convergence.
+ In particular we should avoid excessive engine norms and modes of the engine running without load. At this power factor of the engine is very small (0.17) due to the effects of capacity consumption mode does not load very small.
Equipment capacity compensation
Clearing the grid voltage
The lower voltage network, the capacity compensation is done by:
- Capacitor with a fixed amount of compensation (base compensation).
- Equipment or automatically adjust the compensation capacitor allows a continuous adjustment of the load demand changes.
Note: the capacity to compensate for excess protests and download 800KVAr have continuity and stability, the installation of capacitors at the high pressure often have a better economic efficiency.
Compensation arrangement includes one or more of compensation does not create change. control can be done:
- Manual: using CB or LBS (load - break switch)
- Semi-automatic: used contactor
- Mac directly into electricity load close to the compensation circuit simultaneously closing load.
The capacitors are placed:
- In position for connecting the device's power consumption is love (electric motors and transformers).
- In the location bar contribution levels for many small engine power and load resistance is emotional for us to make up each device one proved too expensive.
- In cases when the load does not change.
Ministry capacitor automatic control (offset animation)
- Clearing capacity is usually represented by means of close control interrupt capacity of each section.
- This device allows drivers compensate capacity automatically, keep the power factor in a limited around for power factor value is selected.
- Equipment is installed at the location where the capacity and capacity work protesting changes in the very broad scope. for example in bar cabinet contributed by distributor, at the connector of the cable axis be large.