What is critical field resistance and critical speed?

Answer:Critical Field Resistance: It is that value of the field resistance at which the D.C. shunt generator will fail to excite. Critical Speed: It is that speed for which the given shunt field resistance becomes the critical field resistance.

What is critical field resistance in a DC motor?

The critical field resistance (RC) of a DC shunt generator is defined as the maximum field circuit resistance with which the shunt generator would just excite. The voltage build-up in a shunt generator depends upon field circuit resistance.

How do you find the critical field 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.

What is meant by OCC of a DC generator and explain?

1. Open Circuit Characteristic (O.C.C.) (E0/If) Open circuit characteristic is also known as magnetic characteristic or no-load saturation characteristic. This characteristic shows the relation between generated emf at no load (E0) and the field current (If) at a given fixed speed.

What is meant by critical field?

For a given temperature, the critical field refers to the maximum magnetic field strength below which a material remains superconducting. As temperature decreases, the critical field increases generally to a maximum at absolute zero.

What is critical resistance in RLC circuit?

The RLC circuit is critically damped when . If R is smaller or larger, the circuit is respectively underdamped or overdamped. For a 150H inductor, and a 10μF capacitor, the critical damping resistance is 7.7kΩ.

What is OCC curve?

The O.C.C. curve is just the magnetization curve and it is practically similar for all type of generators. The data for O.C.C. curve is obtained by operating the generator at no load and keeping a constant speed. Field current is gradually increased and the corresponding terminal voltage is recorded.

What is a shunt field?

A straight shunt-wound motor is a direct-current motor in which the field circuit is connected either in parallel with the armature circuit or to a separate source of excitation voltage. The shunt field is the only winding supplying field excitation.

What is critical field physics?

For a given temperature, the critical field refers to the maximum magnetic field strength below which a material remains superconducting. At that temperature even the weakest external magnetic field will destroy the superconducting state, so the strength of the critical field is zero.

What is meant by critical magnetic field?

[′krid·ə·kəl mag′ned·ik ′fēld] (solid-state physics) The field below which a superconductive material is superconducting and above which the material is normal, at a specified temperature and in the absence of current.