Electric Transformers
Chapter 1 The History of Electric Transformer
INTRODUCTION:
Transformer is a device that transfers electric energy from one circuit to another, usually with a change in voltage. Transformers work only with a varying electric current, such as alternating current (AC). Transformers are important in the distribution of electric power. They raise the voltage of the electricity generated at a power plant to the high levels needed to transmit the electricity efficiently. Other transformers reduce the voltage at the locations where the electricity is used. Many household devices contain transformers to raise or lower house-current voltage as needed. Television sets and stereo equipment, for example, require high voltages; doorbells and thermostats, low voltages. A simple transformer consists essentially of two coils of insulated wire. In most transformers, the wires are wound around an iron-containing structure called the core. One coil, called the primary, is connected to a source of alternating current that produces a constantly varying magnetic field around the coil. The varying magnetic field, in turn, produces an alternating current in the other coil. This coil, called the secondary, is connected to a separate electric circuit. The ratio of the number of turns in the primary coil to the number of turns in the secondary coil—the turns ratio—determines the ratio of the voltages in the two coils. For example, if there is one turn in the primary and ten turns in the secondary coil, the voltage in the secondary coil will be 10 times that in the primary. Such a transformer is called a step-up transformer. If there are ten turns in the primary coil and one turn in the secondary the voltage in the secondary will be one-tenth that in the primary. This kind of transformer is called a step-down transformer. The ratio of the electric current strength, or amperage, in the two coils is in inverse proportion to the ratio of the voltages; thus the electrical
INTRODUCTION:
Transformer is a device that transfers electric energy from one circuit to another, usually with a change in voltage. Transformers work only with a varying electric current, such as alternating current (AC). Transformers are important in the distribution of electric power. They raise the voltage of the electricity generated at a power plant to the high levels needed to transmit the electricity efficiently. Other transformers reduce the voltage at the locations where the electricity is used. Many household devices contain transformers to raise or lower house-current voltage as needed. Television sets and stereo equipment, for example, require high voltages; doorbells and thermostats, low voltages. A simple transformer consists essentially of two coils of insulated wire. In most transformers, the wires are wound around an iron-containing structure called the core. One coil, called the primary, is connected to a source of alternating current that produces a constantly varying magnetic field around the coil. The varying magnetic field, in turn, produces an alternating current in the other coil. This coil, called the secondary, is connected to a separate electric circuit. The ratio of the number of turns in the primary coil to the number of turns in the secondary coil—the turns ratio—determines the ratio of the voltages in the two coils. For example, if there is one turn in the primary and ten turns in the secondary coil, the voltage in the secondary coil will be 10 times that in the primary. Such a transformer is called a step-up transformer. If there are ten turns in the primary coil and one turn in the secondary the voltage in the secondary will be one-tenth that in the primary. This kind of transformer is called a step-down transformer. The ratio of the electric current strength, or amperage, in the two coils is in inverse proportion to the ratio of the voltages; thus the electrical