Unit 4021 Electrical Machines Assignment Brief
| Unit Number | 4021 |
| Unit Title | Electrical Machines |
| Unit Reference Number | M/651/0740 |
| Unit Level | 4 |
| Credits | 15 |
Introduction
Electrical machines are used to convert electrical energy to and from mechanical energy. These are found in manufacturing, transport, consumer appliances, medical and other sectors. People will come across them every day in their home and at work. Electric machines are bidirectional electromechanical energy conversion devices that can be looked in two ways; as a motor which converts electrical energy to mechanical energy; or as a generator which converts mechanical energy to electrical energy. Transducers and actuators are also energy converters and can be found in a wide range of industrial and domestic applications.
This unit introduces students to the construction, modelling and characteristics of a range of electromagnetic machines and their practical application. Among the topics included in this unit are: principles underlying the operation and construction of brushed DC, induction, and synchronous machines (motors and generators), electromagnetic transducers and actuators; and operating characteristics of electrical machines such as voltage, current, speed, torque, power rating, electromagnetic interference (EMI) and efficiency.
On successful completion of this unit, students will be able to gain knowledge and understanding of the operating characteristics of different types of electrical machines and their practical applications in the industry.
Learning Outcomes
LO1 Investigate the different types and operation of electrical machines
LO2 Explore the operation and the various starting methods of induction machines
LO3 Explore the operation and the various starting methods of synchronous machines
LO4 Analyse the operating characteristics, construction and applications of electromagnetic transducers and actuators.
Essential Content
LO1 Investigate the different types and operation of electrical machines
Constructional features:
- Construction, application and characteristics and operation of machine types such as: DC brushed, single phase induction, three phase induction, universal, types of synchronous (BLDC/BLAC, wound rotor)
- Stator, rotor, windings, commutator/slip rings, bearings, case, cooling.
- Typical applications of a range of electrical machines (generators/motors), possible modes of operation (torque, speed, position), and how they are chosen for a specific application (based on key performance parameters: torque-speed characteristic, losses, efficiency, size, cost, etc.).
Brushed and brushless DC machines:
- Brushed versus brushless; advancements and case studies.
- Brushed DC machine equivalent circuit model, analysis of the circuit, testing/characterising.
LO2 Explore the operation and the various starting methods of induction machines
Methods and applications:
- Characteristics and testing (characterisation) of induction machines (locked rotor and no-load tests)
- Equivalent circuit model of one phase with magnetising branch approximation.
Starting methods
- Direct On-Line (DOL)
- Star/Delta
- Variable Frequency Drives (VFD)
Operation, key characteristics, and parameters:
- Voltages, power, speed, torque, inertia, EMI, efficiency, and safety (including health and safety policies, procedures and regulations, compliance, risk assessment process and procedures)
- Protection devices.
LO3 Explore the operation and the various starting methods of synchronous machines
Operation and characteristics of synchronous machines:
- Characteristics and testing of synchronous machines (too much load can cause them to lose sync and torque)
- Focus on two types: Permanent Magnet Synchronous Machines (PMSM – Brushless AC) and the wound rotor for larger applications (grid power generation)
- Starting methods (Closed loop control of PMSM with a VFD)
- Practical applications
- Equivalent circuit model
- Voltages, power, speed, torque, inertia, EMI, efficiency
- Cooling and protection.
LO4 Analyse the operating characteristics, construction and applications of electromagnetic transducers and actuators
Operating characteristics:
- Construction, application, characteristics and testing of electromagnetic transducers and actuators
- Transducer types (active, passive, sensor), actuator types (solenoids, linear, rotary including stepper motors)
- Practical applications
- Voltage and current requirements, hysteresis, and speed of operation.
- Torque/force
- Insulation Protection (IP) rating
- Contact types
- Back Electromotive Force (EMF), EMI and efficiency.
Learning Outcomes and Assessment Criteria
| Pass | Merit | Distinction |
| LO1 Investigate the different types and operation of electrical machines. | D1 Assess the appropriateness of different types of electrical machine for an actual operational requirement. | |
| P1 Examine the types of electrical machine used in industry. P2 Discuss suitable applications for electrical machines in industry. P3 Investigate key parameters of a brushed DC machine. |
M1 Illustrate the operation of the brushed DC machine, considering the equivalent circuit. | |
| LO2 Explore the operation and the various starting methods of induction machines | D2 Critically evaluate the efficiency of available induction machines and make a recommendation for a specific operational requirement. | |
| P4 Explore the operating principles of the three-phase induction machine. P5 Analyse the different methods of starting three- and single-phase induction machines. |
M2 Demonstrate the characterisation of the three-phase induction machine, considering the equivalent circuit. | |
| LO3 Explore the operation and the various starting methods of synchronous machines | D3 Assess the performance and efficiency of permanent-magnet synchronous machines and make a recommendation for a specific operational requirement. | |
| P6 Explain the operating principles of a permanent magnet synchronous machine. P7 Explore a synchronous machine for a specific application, considering their operating characteristics. |
M3 Justify the use of a wound-rotor synchronous machine in a specific application. | |
| LO4 Analyse the operating characteristics, construction and applications of electromagnetic transducers and actuators | D4 Critically analyse the practical application of transducers and actuators in an industrial situation and make recommendations to improve their operating effectiveness. | |
| P8 Analyse the operation, types and uses of electromotive transducers and actuators, by examining features that support their suitability for specific applications. | M4 Justify the selection of suitable transducers for specific industrial applications. | |
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