Circuit control in its simplest form, is the application and removal of power. This can also be expressed as turning a circuit on and off or opening and closing a circuit. Before you learn about the application of circuit control devices, you should know why circuit control is needed. If a circuit develops problems that could damage the equipment or endanger personnel, it should be possible to remove the power from that circuit. The circuit protection devices (fuses and breakers) are not the control devices; these are protection devices that will remove power automatically in event of...

Too much current flowing through an electric circuit can damage the circuit and can create a safety hazard. How much current is "too much current"? That depends on the circuit and its components. For some circuits, 1 ampere would be too much current, while for other circuits 1 ampere would be perfectly acceptable. Circuit protection devices protect electrical equipment by rapidly disconnecting power to components in the event of an abnormal overload conditions resulting from excessive voltages, ground faults, and accidental shorting of a circuit. Two types of circuit protection devices are...

The global energy scenario has undergone a drastic change in the last two decades. Due to ever growing demand and shortage of supply, the cost of fossil fuel (coal, oil and natural gas) is increasing day by day. Increasing consumption has led to environmental pollution resulting in global warming and ozone layer depletion. Consequently, the era of fossil fuel is gradually coming to an end and the attention is focused on the conservation of energy and search for renewable sources of energy, which are environmentally benign. Buildings are major consumers of energy insofar as their construction,...

The majority of electrical energy consumed in most industrial facilities is used to run electric motors. Annual energy operating costs of electric motors usually far exceed purchase prices. For example, a typical 25 horsepower (hp) motor running at full load for 6,000 hours per year would consume nearly $10,000 of electricity annually. An average purchase price for a motor of this size would be only $500 to $600. Energy efficiency decisions are important decisions that affect operating cost for the life of the equipment. By optimizing the efficiency of your motor-driven systems, you can...