How do you find the critical resistance of a shunt generator?

Therefore, the field circuit resistance represented by the line OC, which is tangent to the magnetisation curve is known as critical field resistance (RC) of a shunt generator. Therefore, a shunt generator will build up voltage only if the field circuit resistance is less than the critical field resistance.

How do you calculate shunt field resistance?

The resistance value is given by the voltage drop at the maximum current rating. For example, a shunt resistor rated with 100 A and 50 mV has a resistance of 50 / 100 = 0.5 mΩ.

How do you measure the armature resistance of a DC shunt motor?

A practical way to measure the winding resistance is to use the Ohm’s law: Resistance = Voltage / Current. If you apply a power source to the windings and measure the voltage and current flowing through them, a simple division will yield an accurate value for the resistance.

How do you calculate series generator?

V = Ea – Ia(Ra + Rse)

1. Ea is the armature induced voltage.
2. Ia is the armature current.
3. Ra is the armature resistance.
4. Rse is the series field resistance.

How do you find critical resistance?

Generally data for plotting the open circuit characteristics is given. Plot the characteristics on the graph paper to the scale. Draw the tangent, to the initial part of this O.C.C. then the slope of this line is the critical resistance for the speed at which the data is given.

How do you find critical resistance from OCC?

Draw the given O.C.C and a line tangent to O.C.C. Draw a line ordinate intersecting the field resistance line and a tangent to O.C.C. Multiply the speed by the ratio of intercepts of ordinate drawn between field resistance line and the tangent line to O.C.C. Thus, the result will be the critical speed.

How do you calculate shunt field current?

Calculate the field current for the motor using the formula I = V/R where I is the field current. As an example, assume V is 40 volts and R is 500 ohms: I = 40/500 = 0.08 amps.

How is armature winding resistance measured?

Answer. The windings resistance can be directly measured with an ohmmeter.

How can we measure the resistance in a dc motor?

For the winding resistance use an ohmmeter. For a dc motor measure the resistance between the 2 armature wires. If it is a WYE connected BLDC motor, the resistance is the line-to-line resistance. Thus divide the resistance(l-l) by 2 to get the phase resistance.

What happens when load resistance of a shunt wound DC generator decreases?

When the load resistance of a shunt wound DC generator is decreased, then load current of the generator increased as shown in above figure. But the load current can be increased to a certain limit with (upto point C) the decrease of load resistance. Beyond this point, it shows a reversal in the characteristic.

What are the characteristics of a DC shunt generator?

The characteristics of DC shunt generator mainly include open circuit characteristics, internal characteristics & load or external characteristics which are discussed below. The Open circuit characteristic of a shunt generator is shown below that is similar to a series generator. The OA line signifies the resistance of the shunt field circuit.

How do you calculate the emf of a shunt type generator?

The emf equation corresponding to the shunt type generator is given by E = ФZNP/60A. From the circuit diagram, we can get I a = I L + I f. where

How can the terminal voltage of a generator be maintained constant?

The terminal voltage can always be maintained constant by adjusting the of the load terminal. When the load resistance of a shunt wound DC generator is decreased, then load current of the generator increased as shown in above figure.