Inductive reactance

Resistive reactance Capacitive reactance Inductive reactance... 

Circuits and operating characteristics for mercury lamps Since the voltage drop across all lamps decreases as the current increases, a sufficiently large resistance (DC) or reactance (inductance and capacitance, AC) must be placed in series with the lamp to produce the stable condition of an increase in voltage with increase in current. All circuits should include a voltmeter and an ammeter so that readings may be recorded while the lamp is in use, to detect any... 

This is a vital relationship, which reveals that during start-up and until such speed, the reactance of the motor windings / 2> the rotor current will also remain almost the same as the starting current and will fall only at near the rated speed. (Refer to the current curves in Figures 1.5(a) and (b)). The initial inrush current in a squirrel cage induction motor is very high. In a slip-ring motor, however, it can be controlled to a desired level. (Refer to Section 5.2.1.)... 

This value can be determined from the data available on a per km basis in cable manufacturers catalogues and as provided in the previous tables. For the given a.c. resistance and inductive reactance it can be determined by ... 

The influence of skin effects in a multi-core cable is almost the same as that of a multiphase busbar system, discussed in Sections 28.7 and 28.8. However, unlike a busbar system, the resistance and inductive reactance for various sizes of cables can be easily measured and are provided by leading manufacturers as standard practice in their technical data sheets. To this extent, making an assessment of skin effects in cables is easy compared to a busbar system. Since all the phases in a cable, of a 3-core or 3 72-core are in a regularly twisted formation throughout the length of the cable, they represent the case of an ideal phase transposition (Section 28.8.4(3)) and almost nullify the effect of proximity. 

The inductive reactance, Xl, will tend to offset the ground capacitive reactance X,j and diminish the denominator to a certain value of Xl, say, until it completely offsets the content of X. (Xl= X, ). At higher ratios, when Xl > 3 X. g, the denominator will rise more rapidly than the numerator and will tend to attenuate the Fg a as withand X, but at a slightly higher value of max (Figure 20.7, curve 3). 

The naturai zero phase sequence inductive reactance of the grounded neutral may be considered to be too small compared to this and ignored for ease of calculations. Thus the resistance Rq of the grounded neutral circuit may be considered as its impedance, i.e. 

In an inductive circuit the presence of harmonics is not felt so much as the higher harmonics lend to enhance the harmonic reactance, which causes a dampening effect ... 

From Example 24,3 and Figure 24.25(b) inductive reactance of line = 6 n per phase. 

Xl = power frequency inductive reactance of the circuit. Switching overvoltage... 

Vp, = system voltage V(- = voltage across the capacitor banks Xc = capacitive reactance X] = inductive reactance... 

It can also be applied to an HT distribution network that has a high series inductive reactance to improve its receiving-end voltage. 

To neutralize atid reduce substantially the content of inductive reactance of the line. Refer to a simple transmission network with series compensation, show n in Figure 24.1,... 

Inductive reactance of overhead lines of section B-B. (7) Capacitive reactance of series capacitors. 

It will be pertinent to note that series compenstition on HT lines will be more effective when the line inductive reactance itself is high, as when the line is individually feeding highly inductive loads, such as an induction or an arc furnace or other similar loads. Nevertheless, it can also be effectively applied on overloaded distribution networks similar to the one we have considered above, to raise the line capacity and reduce the voltage dip at the receiving end. 

Xl = inductive reactance of the wliole line length Influence of line length... 

Figure 28.25 Distribution of inductive reactance and impedance of each phase in a three-phase system...

Determining the size of reactor Consider a three-phase bus system as shown in Figure 28.27. If and X are the inductive reactances of each phase on account of skin and proximity effects respectively, then the impedances of each of the three phases can be expressed as... 

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