Shunt capacitors

Resonance may also occur between the line inductance, series reactors and shunt capacitors. 

Shunt capacitor - connected across the inductive circuit to improve its p.f. 

Harmonic output of a capacitor unit The rating of a shunt capacitor unit... 

If Xl is the 6% series reactance of the value of the shunt capacitors installed, then... 

Shunt capacitors 1120 kVAr in each arm of a double star as shown below. Each unit 80 kVAr... 

The shunt capacitors can be provided on the LT or the HT side, whichever is more convenient. In the above case, since it is large, the HT side of the load-end transformer will be more convenient. The receiving-end transformer, however, will now be operating under more stringent conditions that must be taken in account or the capacitors may be provided on the LT side to relieve this transformer also from excessive currents. In Figure 23.18(b) we have considered them on the LT side. 

Figure 23.29(a) Determining the kVAr rating of a shunt capacitor... 

Shunt capacitors for a.c. power system having rated voltages above 1000 V I3925-I/I998 BS EN 60871-1/1998... 

Series and shunt capacitors both provide the same degree of compensation. But it is the correct reactive support that provides a more stable system less prone to load and voltage lluctuations. Thus i Judicious choice between the shunt and the series capacitors is required. In the following our main thrust is to arrive at the most appropriate type and extent of reactive support to achieve a higher level of utilization of a power transmission or distribution system, on the one hand, and more stability, on the other. 

We will notice subsequently that series and shunt compensation are complementary. What a shunt capacitor cannot do, a series capacitor does and vice versa. On a secondary transmission system, say up to 66 kV, a shunt compensation may always be necessary to improve the power factor, as the load would mainly be indtictive. A series compensation may become essential, to improve the stability of the system, to cope with load fluctuations, switching of non-linear loads and voltage fluctuations occurring on the other power system or the grid to which this system may be connected. 

In LT systems reactive control is provided to improve the load p.f. and hence its load-carrying capacity, as discussed in Chapter 23. This is achieved by offsetting the inductive content of the load ctirrcnt at the receiving or the consumer end by the use of shunt capacitors and hence support the system by reducing line losses and improving its active load current (/ cos 0) carrying capacity. 

The effect of p.f. can be controlled by shunt capacitors, near the load point and the Ferranti effect by altering the line parameters. Since... 

The power factor can be improved with the use of shunt capacitors at the load points or at the receiving end, as discussed above. It is not practical to have a near-fixed loading for all hours of the day. Moreover, there may also be seasonal loads which may upset the parameters considered while installing the capacitor banks. In such conditions the system may therefore have to be underutilized or run under a high risk of instability during... 

Adding shunt capacitors would also reduce Zq but would raise the electrical line length hence it is not considered. Moreover, on EHVs, the charging shunt capacitances, Cq, as such require compensation during light loads or load rejections to limit the voltage rise (regulation) at the far end or the midpoint. Hence no additional shunt compensation is recommended. 

Standard for series capacitors in power systems Shunt capacitors, both LT and HT... 

Esiernal fuses for shunt capacitors Loss voltage cartridge fuses Fliuh sollaee fuses. 

For overloading during normal operation, which may be due to load fluctuations or failure of a few capacitor elements, normal overload protection will suffice, as discussed for shunt capacitors (Section 26.1.1(3)). This protection may be provided in conjunction with the line fault protection scheme, discussed below. 

V or less in 1 minute in LT and in 10 minutes in HT shunt capacitor units or banks and in 5 minutes in series capacitors. The arrangements of discharge devices are illustrated in Figure 25.8. ... 

This is an alternative to the ageing test and is applicable for shunt capacitors of 1000 V and above. It is an in-house process test and is carried out on the capacitor elements before they are assembled into a capacitor unit to ascertain their dielectric stability against repeated overvoltages. For the test procedure refer to lEC 60871-2. 

Industrial a.c. Networks Affected by Harmonics — Application of Filters and Shunt Capacitors Low Frequency EMC Phenomena Terminology... 

Internal fnses and internal over-pressure disconnections for shunt capacitors. Application gnide for power transformers Specifications for conduits for electrical installations. 

Shunt capacitors for AC power systems having a rated voltage above 660 V. Part 1 General-performance, testing and rating-safety... 

Figure 24.7. The proportional-plus-derivative controller. Derivative action is accomplished by a shunt capacitor C across Rf. When deviation from the setpoint is rapid, the low reactance of the capacitor causes less negative feedback—hence, greater amplifier gain. The derivative time resistor Ra allows adjustment of the magnitude of derivative control action to a given rate of change of the error signal. Courtesy of the Foxboro Company.

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