DC reversible variable speed motor
reversible variable speed system
variable speed variable pitch
variable speed-variable pitch
variable-speed variable-frequency
Variable-speed Variable-pitch
variable-speed variable-pitch wind turbine
variable speed variable frequency system
frequency self-controlled voltage-variable speed-variable system
direct current and reversible speed regulation
pneumatic reversible drill
reversible variable frequency power supply
Reversible variable length coding
reversible variable-length codes
symmetrical reversible variable length code
AC DC AC current source variable speed system by using converter