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
In modern political theory, a parliament is the legislature within a parliamentary system of government. Historically, parliaments include various kinds of deliberative, consultative, judicial assemblies.he parliamentary system can be contrasted with a presidential system, on the model of the United States' congressional system, which operate under a stricter separation of powers whereby the executive does not form part of, nor is appointed by, the parliamentary or legislative body.