What is reactance voltage in dc generator

An auxiliary winding is wound on the interpole and connected in series with the main field. At high speed and heavy load, the bias winding gave little opposition to the strong interpole magnetic field, which is needed to suppress reactance e.

At low speed and heavy load, the bias windings will oppose the interpole windings in reducing its strength and increase the efficiency of the generator. The interpole with auxiliary or bias winding relates to direct current motors and generators, and more particularly, to variable speed shunt motors of a size in which variation of the commutating pole excitation is required for good commutation under different shunt field conditions.

Otherwise, poor commutation results. This problem is overcome by providing an auxiliary commutating pole winding which is energized so as to be responsive to adjustments in the excitation of the shunt type field winding but not directly responsive to the magnitude of the load current.

In this case, some means is necessary to reduce the auxiliary winding excitation somewhat, and to reduce the effective excitation due to the auxiliary cumulative winding to zero.

In the method described in the abovementioned patent, it is not possible to reduce the excitation of the auxiliary cumulative winding to zero but a compromise auxiliary winding excitation is provided so as to obtain not quite the best commutation at full load but still giving preference to the commutation conditions at full load as distinguished from the commutation conditions at no load. The principal object of the auxiliary winding is to provide an improved field structure which reduces or eliminates commutator sparking under weak field, no load conditions.

Open navigation menu. Close suggestions Search Search. User Settings. Skip carousel. Carousel Previous. Carousel Next. What is Scribd? Reactance Voltage Assignment. Uploaded by Farisz Malek. Document Information click to expand document information Description: University Assignment. Did you find this document useful? Is this content inappropriate? Report this Document. Description: University Assignment. Flag for inappropriate content.

Download now. Related titles. Carousel Previous Carousel Next. Jump to Page. Search inside document. Figure 2 Not all sparking at the commutator is reactive sparking, sparks may also be caused by worn or sticking brushes, incorrect spring tension, commutator flats and proud mica. The reversing voltage may be produced in the following two ways: 1. By brush shifting 2. By using interpoles or compoles 1. This method suffers from the following drawbacks: a The reactance voltage depends upon armature current.

The interpoles perform the following two functions: a As their polarity is the same as the main pole ahead for a generator , they induce an e. This unequal field distribution produces the following two effects: a The main flux is distorted. Under such a condition, the armature reaction produces the following two effects: a It demagnetizes or weakens the main flux. Lavankumar Mudiraj. Simon Verboven. Vanusha Azzriel. Wonshik Choi.

Kusum Verma. Costache Dan. Sunil Singh. Diwosh Sh. Engkiong Go. Vikas Gupta. Gadam Siva Charan Das. Mohamed Hichem Guesmi. Arthur Dias. Anonymous 1Uakesa. Eng-Abdallh Greman. Janet Walde. More From Farisz Malek. Farisz Malek. Motors Losses in a D. Motor Efficiency of a D. Motors Troubles in D. Motors Speed Control of D. Shunt Motors Speed Control of D. Motor Starter Types of D. Shunt Motor Efficiency of a D. Branch : Electronics and Communication Engineering.

Unit : DC Generator. Calculation of Reactance Voltage. If L is the inductance of the coil, then reactance voltage is given by; Reactance voltage For linear commutation.

Now the brush entirely touches the commutator segment 3 as shown in figure 1. At that condition, each coil meets the commutator segment 3 supplies current I to that segment. So the brush current is 2I.

After further progress, the brush comes in contact the segment 2. At that position the brush short circuits the segment 2 and 3. As per the position of Figure 2, the brush touches one-fourth of segment 2. The total brush current is still 2I now. The brush receives the currents from the coils according to the contact area with the commutator segments.

After half of the commutation period, the brush has come to the middle of the short circuit. At that position there is no current in the coil B. At that instant current, I passes to the brush from coil A and C as shown in figure 3. So here also the total brush current is 2I. Thus from the above explanation, we have come to know that the sharing of current from the commutator segment to the brush is exactly proportional to the contact area of that segment with the brush.

It needs not to say that it is the most ideal condition for commutation in DC machines. If the current value during reversal has a uniform rate, we will get the straight line as shown.