SKOT 191 - Machine Controls 1Credits: 3 Present students with mechanical background the essentials of wiring and troubleshooting controls in production machinery. Studies AC/DC circuits, fundamentals of hydraulics and pneumatics as they pertain to machine control circuitry. Emphasizes relay ladder diagrams, simple debugging and nomenclature necessary to communicate with design engineers and other trades in the installation and troubleshooting of panel wiring.
Prerequisite(s): None Corequisite(s): None Lecture Hours: 45 Lab Hours: 0 Meets MTA Requirement: None Pass/NoCredit: No
Outcomes and Objectives 1. Understand the fundamentals of basic electricity.
A. Identify materials that can be used as conductors, resistors, and semi-conductors via their atomic structure.
B. Idenitfy the differences between volts, amps, resistance and watts and how they interact with each other (ohms law).
C. Identify different types of circuits, (series, parallel and series parallel).
D. Identify voltage drop in conductors via length and size, resistances and loads.
E. Identify the differences between AC, DC and pulsating DC.
2. Understand the basic types of transformers and power supplies used in industry.
A. Identify how a current traveling through a wire creates magnetism.
B. Identify the transformer action as current passes through I coil and interacts with another.
C. Identify step-up transformers, step-down transformers, and isolation transformers.
D. Identify the operation of 3-phase transformers.
E. Identify how DC power supplies are constructed using diodes and filters.
3. Understand the basic types of fuses, circuit breakers, and disconnect switches.
A. Identify the many different types of fuses in categories (normal, fast blow and slow blow).
B. Identify the different types of circuit breakers and their functions.
C. Determine if a circuit breaker should be used or a fuse to protect varying types of circuits.
D. Identify the different types of disconnects, their uses and panel placements.
4. Understand input, output and logic devices.
A. Identify single pole, double pole and triple pole switches by device and symbol.
B. Identify single throw, double throw and neutral center switches by device and symbol.
C. Identify output-indicating devices such as push-to-test lamps LED indicators.
5. Understand control relays, timing relays, latching relays and contactors and motor starters.
A. Identify the basic parts of the typical relay.
B. Identify the electrical symbols used to show relays and contactors on prints.
C. Examine inrush current and holding currents created by relay coils.
D. Identify load types controlled by relays (resistive / inductive).
E. Identify current ratings of relay and contactor contacts.
F. Examine the operation of timing relays their operation and circuit uses.
G. Examine the operation of latching relays, their operation, and circuit uses.
H. Examine various motor starters determining size, current ratings and contact arrangement.
I. Identify motor overloads with respect to motor horsepower and duty cycle.
J. Identify motor starting circuit circuits for across line starting, motor reversing and multi-speed motors.
6. Understand “line sequence diagrams,” “ladder diagrams” and “circuit symbols.”
A. Learn the advantages of quality line sequence diagrams.
B. Learn to read and troubleshoot from ladder diagrams and the circuit symbols used on them.
7. Understand the operation of pneumatic and hydraulic valves and the solenoids that operate them.
A. Examine valves and follow the flow of the oil or air.
B. Examine the valve solenoids and their armatures.
C. Identify voltage and current requirements.
8. Learn about the many various motion-sensing devices.
A. Identify limit switches, proximity switches, cam switches, photoelectric switches, magnet operated switches and vane switches.
B. Identify each switch type by electronic symbol.
C. Identify each switches operating characteristics.
D. Identify proper placement of each type switch.
E. Identify troubleshooting techniques to locate faulty switch problems.
9. Understand pressure control used with electrical circuits.
A. Examine pressure switches and pressure transducers.
B. Understand pressure control activation and re-activation logic.
10. Understand the operation of electronic and mechanical timers and counters.
A. Examine mechanical timers and learn the operation and wiring process.
B. Examine mechanical counters and compare their operation with mechanical timers.
C. Examine electronic timers and counters and learn functionality and accuracy.
11. Understand basic differences and operation of motors.
A. Examine basic operation of a DC motor.
B. Examine the operation of a basic single phase AC motor.
C. Examine the operation of split-phase motors.
D. Examine the operation of shaded pole motors.
E. Examine the operation of squirrel cage motors.
F. Examine the operation of 3 phase motors.
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