Electrical Equipment and PLC's 1 ELEX 3325

Electrical Safety

• Understand and apply safe work practices when working with voltages above 50V.
• Describe the factors which affect the severity of an electric shock.
• In the lab, lock the power supply safety switch into the OFF position at all times except when making measurements.
• Arrange wiring and connections securely and safely.
• Make safe measurements through consistent use of the 'one-hand rule'.

Power Factor and Power Quality

• Analyze the power factor and the power quality of an electrical circuit.
• Describe, measure and correct the displacement power factor of an electrical circuit.
• Describe how non-linear loads create distortion and unwanted harmonics in electrical circuits.
• Measure the harmonics that exist within an electrical system.
• Describe distortion power factor and power quality.

Three Phase Power

• Analyze three phase circuit configurations.
• Describe the generation of three phase power.
• Identify characteristics of three phase power and differentiate from single phase power.
• Analyze wye and delta connected, 3-wire circuits.
• Analyze 4-wire circuits.
• Analyze balanced and unbalanced loads.
• Analyze non-linear loads and harmonics.
• Correct the power factor of a 3 phase load.

Protective Devices

• Analyze and explain the operating principles of protective devices in electrical circuits.
• Explain the operation of low voltage fuses.
• Explain the operation of thermal and of magnetic circuit breakers.
• Explain the inverse time characteristics of protective devices.
• Explain the interrupt capacity of protective devices.
• Interpret fuse and circuit breaker curve data so as to apply simple protective coordination.
• Explain the operating principles of ground fault circuit breakers.

Magnetic Circuits

• Analyze and explain the properties of magnetic materials and magnetic circuits.
• Relate magnetic circuit quantities to their electrical analogs
• Explain the magnetization, dipole alignment and saturation of ferromagnetic cores.
• Interpret magnetization curves and determine their electrical implications.
• Relate hysteresis and energy loss in a magnetic circuit.
• Relate eddy currents and energy loss in a magnetic circuit.
• Determine the forces on a current carrying conductor in a magnetic field.
• Determine the induced voltage in a conductor in a magnetic field.

Transformer

• Analyze the behaviour of transformers in electrical circuits.
• Outline transformer construction.
• Explain transformer principles of operation using Faraday's and Lenz's Laws.
• Describe the magnetic flux effects of an electrical load connected to a transformer.
• Incorporate the transformer equivalent circuit in circuit analysis.
• Determine transformer losses.
• Determine transformer parameters via laboratory test procedures.
• Connect transformers to obtain specified voltage and phase shift objectives.
• Analyze and apply autotransformer principles.
• Analyze transformer inrush current.
• Calculate circuit quantities on both the primary and the secondary side of transformers.

Induction Motor

• Analyze the behaviour of three-phase induction motors.
• Outline induction motor construction.
• Explain induction motor principles of operation.
• Analyze normal load behaviour.
• Analyze overload behaviour.
• Analyze off-voltage and off-frequency behaviour.
• Analyze inrush current.
• Analyze and explain the operation of the wound rotor induction motor.

DC Motor

• Analyze the behaviour of DC shunt and series wound motors
• Explain DC machine principles of operation.
• Outline DC machine construction.
• Explain the electro-mechanical rectification performed by commutator and brushes.
• Analyze and explain self-excited and separately excited machines.
• Analyze and explain shunt, series and compound excitation.
• Analyze normal load behaviour.
• Analyze and explain 'loss of field' and its effects on machine behaviour.

Stepper Motor

• Analyze the behaviour of stepper motors.
• Outline stepper motor construction.
• Explain stepper motor principles of operation.
• Explain resolution, step angle, stepping frequency, step accuracy.
• Explain step operation, half-stepping and micro-stepping.
• Design and connect test circuits to control (via button press) the rotation of both a 2-phase and a 4-phase stepper motor.

Motor Control with Relays

• Analyze control circuits, explain the practices employed and apply accepted standards to the design of several control systems.
• Explain the operation of contactors, overload relays and pilot devices.
• Interpret and design control circuits using ladder diagrams.
• Design and implement control circuits with relays.

Motor Control with Programmable Logic Controllers (PLCs)

• Design and implement control circuits with a programmable logic controller.
• Implement PLC control programs that meet the safety requirements of the Workers Compensation Board (and other agencies).
• Develop familiarity with a small-scale PLC via trial exercises in common logic in ladder form.
• Analyze selected electrical control circuits of increasing complexity and redevelop these designs to each use a PLC-based approach. Refine the systems where possible to take advantage of PLC features.
• Interpret written sequences-of-operation for proposed control systems and design and document a PLC-based system to meet each given sequence-of-operation (SO).

Effective as of Fall 2005