A variable-frequency drive (VFD) (also termed adjustable-frequency drive, variable-speed drive, AC drive, micro drive or inverter drive) is a type of adjustable-speed drive used in electro-mechanical drive systems to control AC motor speed and torque by varying motor input frequency and voltage.ariable-frequency drives are also categorized by the following load torque and power characteristics: 1  Variable torque, such as in centrifugal fan, pump, and blower applications. 2  Constant torque, such as in conveyor and positive-displacement pump applications.
For example, the UK is a unitary state (for the most part) whereas the US is a federation. A parliamentary form of government simply means that the executive branch/ministers/cabinet are part of the legislative body. Both unitary and federal states can have parliaments. For example, India is a federation with a parliamentary system where as the UK is a unitary state with a parliamentary system. m200220232
A parliamentary system is a system of government in which the ministers of the executive branch are drawn from and accountable to the legislature, such that the executive and â¦ legislative branches are intertwined. In such a system, the head of government acts as de facto chief executive and chief legislator.n contrast to a presidential republic and the semi-presidential system, the head of state usually does not have broad executive powers as an executive president would, because much of those powers have been granted to a head of government (usually called a prime minister).