Course Overview
This course continues from ELEX 3325, beginning with applied electrical control. The student will commence this work by carrying out several equipment control designs, using both the hardwired relay approach and the PLC approach; standard practices for documentation will be stressed for both. The PLC work will include a retrofit or modernisation task. The course then reviews protection, expanding upon overcurrent problems and other electrical abnormalities. A detailed study is made of electrical protective devices, including fuses, breakers, motor overload protectors, varistor devices and protective relays. Power quality problems are then explored, with a focus on those caused by rectification. The course continues with a review and further study of AC and DC motors; the focus will be the equivalent-circuit model approach to the solution of applications problems. This will lead into the consideration of nameplate ratings, in terms of a motor's ability to do a job, whether continuous, intermittent or periodic, and in terms of the effects of duty cycle and temperature on life expectancy. The course closes with a detailed look at AC and DC motor starters and their effects on the motors they control. Quite a bit of lab work will entail troubleshooting problems that are often obscure!
Prerequisite(s)
- 50% in ELEX 3325
Credits
7.0
- Retired
- This course has been retired and is no longer offered. Find other Flexible Learning courses that may interest you.
Learning Outcomes
HARDWIRED AND PROGRAMMABLE CONTROL
Define problems requiring electrical control and design appropriate electrical control systems using relays and/or programmable logic controllers.
Employ design strategies suitable for given circumstances, as in 'appropriate technology!' (i.e. What is best for something new? And for Golden Oldies? What works for retrofit?)
- Specify, design and document control tasks using conventional relays and timers.
- Specify, design and document control tasks using programmable controllers.
- Prepare complete and proper documentation of either system in accordance with accepted industry practices.
ELECTRICAL PROTECTION
Assess the need for electrical protection and incorporate various protective devices into the design of electrical systems (fuses, circuit-breakers, other switchgear, protective relays, instruments transformers, overvoltage transient suppressors).
Discuss recent advantages in electrical protection.
- Explain the range of electrical abnormalities, their causes and consequences.
- Categorize the various protective devices used to mitigate electrical abnormalities.
- Assess and select fuses with regard to rupture capacity, let-through energy and current limitation.
- Calibrate motor overload protection and select appropriate motor branch fuses.
- Analyze circuit-breakers according to their types, classes and operating characteristics with emphasis on achieving high rupture capacity and current limiting action where needed.
- Discuss the applications and limitations of other switchgear including disconnect switches, load breaks and safety switches.
- Discuss protective relaying in terms of protection offered, operating fundamentals and applications.
- Select instrument transformers appropriate to drive protective relays based on analysis of possible power system faults.
- Discuss the operation of various overvoltage transient suppressors and their selection using Basic insulation Level (BIL) criteria.
RECTIFICATION AND POWER QUALITY
Review and further explore the third-term discussion of the fundamentals of magnetic circuits and rectification, and their effects on the AC power supply. Undertake lab exercises to measure these using appropriate techniques.
- Investigate various configurations of rectifier or transformer in terms of harmonic generation.
- Analyze and identify dominant harmonics, and determine the problems these can cause to equipment and plant in power systems. Specific issues to be explored will include:
- 'triplen' current excesses in neutrals and transformer windings,
- Negative-sequence fields in motors, and
- Transformer saturation caused by DC offsets
- Describe and apply true-RMS and waveform and spectral measuring apparatus.
ALTERNATING-CURRENT AND DIRECT-CURRENT MOTORS: SPECIFICATIONS
Explain in detail the operating characteristics, design and classes of AC and DC motors.
- Review and analyze further the theory of AC rotating-field induction motors.
- Apply the equivalent-circuit model of AC motors to motor applications problem-solving.
- Review and analyze further the theory of DC stationary-field motors.
- Identify and assess the nameplate ratings of electrical machinery, in terms of machine type and configuration, power, temperature rise, and service factors. Assess predicted life of machines as a function of ratings, environment and application.
GENERATORS
Discuss practical comparisons of rotating-field and stationary-field generators.
- Distinguish between rotating-field and stationary-field machines.
- Discuss geometry and dynamics (pole-count versus speed and physical layout), size, and cooling vehicles for generators of various sizes. Describe excitation systems. (In large measure, this will be accomplished in the course of power plant site visits.)
MOTOR CONTROL
Assess the nature of motor control in terms of practical motor operation and protection of the electrical supply.
Analyze and apply a range of motor starters including full voltage, reduced voltage and reversing starters, as well as braking starters. Consider thermal and possible life-cycle effects of these starters on the motors being controlled.
Assess methods of stopping motors quickly for expedience and/or safety.
- Analyze and test various motor starters including
- Full voltage nonreversing (FVNR),
- Full voltage reversing (FVR), and
- Full voltage breaking starter.
- Analyze, test and troubleshoot various types of reduced AC and DC motor starters, including semiconductor types.
- Discuss changing trends in drive application - AC vs DC. (Transit and 'Heavy-Haul' site visits should serve as good lab components for this study.)
Effective as of Fall 2003
Programs and courses are subject to change without notice. Find out more about BCIT course cancellations.