Chapter 11, Problem 12RP

2. Refrigerators to maintain the product at a given temperature have a control system. a) Explain how the control system is or how you think it should be (Make a diagram). b) Make the typical block diagram of a control system and identify the components in the refrigerator system. c) Classify the control system.

3. Internal combustion engines require a cooling system to function properly, which maintains the engine temperature at an appropriate value. Neither too high nor too low. There are several systems to control this temperature, the two best known are: • The classic one that uses a thermostat that regulates the flow of coolant (water), and where the fan is mechanically coupled to the engine. • In more recent vehicles, in addition to the thermostat, a temperature controller is used that turns an electric fan on and off. Select one of the two systems mentioned above and: a) Explain how it works, using diagrams. b) Make the typical block diagram of a feedback control system, identifying the components of the system. c) Classify the control system.

A 3-phase, star connected, 10 kVA, 380 V, salient pole alternator with direct and quadrature axis reactances of 15 and 8 0/ph respectively, delivers full-load current at 0.8 power factor lagging. Neglect the armature resistance. Determine the following: (a) The load angle, (b) The direct axis and quadrature axis components of armature current, (c) E.M.F induced voltage of the alternator, (d) The voltage regulation, and (e) The developed power by the alternator?