TABLE OF CONTENTS Michael Kargl
Martin Engineering Co.
Wiley Steen
Consultant
This chapter will discuss electrical and magnetic properties along with theory of operation of the induction motor. Adjustable speed drives (ASDs) and their control of induction motors will be discussed, along with various motor applications and considerations regarding alternating current (AC) induction motors on oil rigs.
The properties of electricity are voltage, current, and resistance. Voltage (also known as electromotive force, or emf ) is the strength of a circuit that causes current to flow through the resistance in the circuit. It is a force that causes electrons to move from one atom to the next. Voltage is analogous to pressure in the mechanical system. Voltage is measured in volts.
Current, measured in amperes, is the measurement of electrons flowing through a conductor. One ampere is 1 coulomb passing an imaginary plane in 1 second. A coulomb is a quantity of electrons (6.24 10 18). The amp, in the mechanical system, is analogous to flow rate, such as gpm.
Resistance is measured in ohms and is a measure of a circuit s resistance to current flow. Resistance is that property that opposes the movement of electrons from one atom to the next. As resistance goes up, current flow decreases if the voltage is constant. As resistance goes down, current flow increases. Resistance varies with temperature. As temperature increases, resistance increases.
In direct current (DC) circuits, Ohm s law defines the relationship between voltage, current, and...
