A controller, or a compensator is an additional system that is added to the plant to control the operation of the plant. The system can have multiple compensators, and they can appear anywhere in the system: Before the pick-off node, after the summer, before or after the plant, and in the feedback loop.
B unit of the Russian 3TE10MK locomotive. A B unit, in railroad terminology, is a locomotive unit (generally a diesel locomotive) which does not have a driving cab or crew compartment, and must therefore be controlled from another, coupled locomotive with a driving cab (an A unit). The terms booster unit and cabless are also used.
British thermal unit (BTU) Any of several units of energy (heat) in the HVAC industry, each slightly more than 1 kJ. One BTU is the energy required to raise one pound of water one degree Fahrenheit, but the many different types of BTU are based on different interpretations of this âdefinitionâ. In the United States the power of HVAC systems (the rate of cooling and dehumidifying or heating) is sometimes expressed in BTU/hour instead of watts.