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Effective human interventions - EHI

DC Machine Operation, Maintenance & Inspection

Thu, 05 Mar 2009 13:02

“DC Ain't Dead Yet.”

This two day course will cover DC machine theory and operation, as well as repair tips.

Topics will include testing, data analysis and motor theory.

Discussions will cover basic materials, loading and stresses, the most common failure modes and recommendations for repair practices for DC applications.

Upon completion of this course, participant should be able to:

• Develop an understanding of DC motor theory and how it works
• Gain better knowledge to proper machinery operations
• Develop a basic understanding of the materials making up a DC motor and their failure modes
• Revise operating procedures for trouble free operation
• Determine which monitoring techniques offer the best opportunity for monitoring

Benefits include:

• Participation in an interactive workshop
• Learn from a recognised expert with cross industry experience
• Comprehensive course documentation
• Certificate of attendance

WHO SHOULD ATTEND:

This course is designed for maintenance technicians, engineers, or anyone requiring a basic understanding of DC motors and the internal parts that make them work.

Day One

• Principles of energy conversion
• The electromagnetic induction theory
• Basic magnetism theory
• Construction of the DC machine
• The flux patterns in a DC machine
• Developed power
• Dimensions of the DC machine

• Development of the simplex lap winding
• Development of the duplex lap winding
• Development of the simplex wave winding
• Development of the duplex wave winding
• Other types of windings
• The equaliser function and development explained

• Types of commutators
• Commutator construction
• Commutator testing
• Commutator maintenance

• Construction of the yoke
• The main fields
• The commutating fields
• The compensating winding

Day Two

• The shunt machine
• The series machine
• The compound machine
• Overview of the function and operation of the main components

• Brush materials and brush selection
• Brush configurations and brush tension
• Setting up the brush stagger and brush arm spacing
• Brush neutral setting
• Checking polarity of fields and commutating poles

• Winding resistance of armature and field systems
• Insulation resistance tests
• Effect of temperature on resistance measurements
• High voltage withstand tests
• Commutator testing
• Brush potential and black band tests
• Impulse testing

• Commutation problems
• Typical faults and symptoms
• The polarisation index test and dry-out of moisture
• The open circuit characteristic curve test
• The self excited machine
• Typical Ward Leonard set operation
• Typical thyristor drive operation
• Basics of closed loop control

Course Synopsis

This course provides a comprehensive overview of DC machine which will enable delegates to understand the fundamentals of DC motors and their application.

This course is designed to familiarise the delegate with motor basics, parts of a DC motor, how DC motors operate, and different types of DC motors.

In addition, the field construction of the DC motor and the various elements of the commutator are detailed, as well as interpreting the wiring diagrams and troubleshooting DC motor problems.

About Your Course Facilitator

M. M. (Thys) Botha is an independent electrical machines consultant with years of experience as rotating machines specialist.

He started his career at ISCOR in 1957, joined Dunswart Steel as Electrical Engineering Superintendent in 1977, later moved to GEC Machines as Divisional Director in 1984 and joined LH Marthinusen (the largest repairer of electrical machines and transformers in South Africa.) as Technical Director in 1987 until his retirement in 2006.

He is currently doing consulting work for LHM, Goldfields, SAVCIO and training at a number of companies like AngloGoldAshanti, OMNIA and ESKOM.

Thys has a very strong background in commissioning of plants, ex. ISCOR's North Works at Vanderbijlpark. Thys was responsible for the full engineering function covering all aspects of projects, procurement, installation, commissioning, maintenance, repair and design.

His qualifications include Matric with University exemption, Engineering Diploma, Government Certificate of Competency (Electrical Factories), B. Com and Hons. B. Com.

Thys is a Member of the Institution of Certificated Electrical and Mechanical Engineers (ICMEESA), Associated Member of the South African Institute of Electrical Engineers (SAIEE), Member of the High Voltage Rotating Machines Working Group of the SAIEE.

He is also an author of a number of papers on electrical machines in local and overseas publications and conferences.

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