Series connected single phase commutator motor speed control system - has shunt resistor across series connection of armature winding and triac, and RC voltage divider connected across supply

摘要

The series connected commutator motor speed control system has a control device producing phase gating ignition pulses and having an RC voltage divider (4, 5) which is connected directly to the a.c. voltage source. The output of the voltage divider is connected over a resistor and diac to the control electrode of a triac. - A shunt resistor (9) is connected in parallel with the series connection of the triac (7) and automatic winding (8). The resistor is sized so that an additional a.c. excitation is generated in the motor which is opposed to the residual excitation generated by the preceding half wave and is greater than the latter excitation.