Electrical Engineering ⇒ Topic : Effects of Thryistor Power Supply on the D.C..Motor Performance

Effects of Thryistor Power Supply on the D.C..Motor Performance

(1)The performance of a D.C. motor may be affected by the thyristor power supply as follows

(2)The output voltage may change very rapidly in comparison to that of a motor-generator set owing to the absence of field time constants associated with the generator.

(3)The output voltage from thyristor convertor consists of a D.C. component and A.C. harmonic components. Torque is developed by the D. C. component of the current whereas heating is developed by the r.m.s. (effective) value of current.In the event of thyristor fault (when operating in the invertor mode) the armature current may rise to an abnormally high value.

(4)The commutating ability is seriously affected by the presence of harmonic currents.

(5)The other effects of thyristor supply on D.C. motor performance are :

• Heating of interpole winding;
• Saturation of interpole magentic circuit;
• Transformer voltage at the brushes
• Increase in voltage per commutator segment