Critical Field Resistance

Critical Field Resistance Points : Critical Field Resistance It has been already stated that the maximum voltage which a generator can generate is given by the point of intersection of field resistance line with the open-circuit characteristic. If the line OA represents the field resistance, then the maximum emf generated is Oa₁, if the field resistance is increased to the value represented by line OB, the generated voltage will be 0b₁ and if it is further increased so that the line representing the field resistance becomes tangent to the curve, as line OC, then emf generated is OC₁ and the value of resistance given by this line is called the critical resistance. If field resistance is further increased beyond critical resistance, as represented by line OD the generator will not excite because the line OD has got no point of intersection with the magnetic characteristic (ignoring initial portion of the curve).