11. Consequently, converters built with mercury arc valves are known as line-commutated converters ( LCC ). 12. As a result, they can be used to make " self-commutated converters ". 13. A major drawback of HVDC systems using line-commutated converters is that the converters inherently consume reactor. 14. These errors are detected, commutated , amplified, and used to control the antenna-positioning servos. 15. As a result, IGBTs can be used to make " self-commutated converters ". 16. With such converters, the harmonic spectrum is generally shifted to higher frequencies than with line-commutated converters. 17. Being self-commutated , the converter no longer relies on synchronous machines in the AC system for its operation. 18. SCRs do not turn off or " commutate " automatically when the gate control signal is shut off. 19. The basic building-block of a line-commutated HVDC converter is the " six-pulse bridge ". 20. In a brushed DC motor the field is static but the armature current must be commutated , so as to continually rotate.
