Motors and Variable Speed Drives

Motors and Variable Speed Drives

Maximum efficiency, reliability, and longevity of the various types of motors, and variable-speed drives are of great concern to many industries. These objectives can only be achieved by understanding the characteristics, selection criteria, common problems and repair techniques, preventive and predictive maintenance. This seminar is a MUST for anyone who is involved in the selection, applications, or maintenance of motors, and variable-speed drives. It provides the latest in technology. The seminar covers how this equipment operates and provides guidelines and rules that must be followed for a successful operation. Their basic design, operating characteristics, specification, selection criteria, advanced fault detection techniques, critical components as well as all maintenance issues are covered in detail.

OBJECTIVES

To provide a comprehensive understanding of the various types of motors, and variable-speed drives. Participants will be able to specify select, commission and maintain this equipment for their applications. To achieve reduced capital, operating and maintenance costs along with increase in efficiency.

This on-site/in-house training course is available worldwide. Please contact the school for details.

This on-site/in-house training course is available worldwide. Please contact the school for details.

Maximum efficiency, reliability, and longevity of the various types of motors, and variable-speed drives are of great concern to many industries. These objectives can only be achieved by understanding the characteristics, selection criteria, common problems and repair techniques, preventive and predictive maintenance. This seminar is a MUST for anyone who is involved in the selection, applications, or maintenance of motors, and variable-speed drives. It provides the latest in technology. The seminar covers how this equipment operates and provides guidelines and rules that must be followed for a successful operation. Their basic design, operating characteristics, specification, selection criteria, advanced fault detection techniques, critical components as well as all maintenance issues are covered in detail.

Day I

REVIEW OF FUNDAMENTALS/INTRODUCTION TO MACHINERY PRINCIPLES

* Capacitors, dielectrics, magnetic field, Ampere’s law, Faraday’s law, inductance, and alternating currents
* Introduction to Machinery Principles: magnetic circuits, permeability, flux, ferromagnetic cores, reluctance, saturation, and hysteresis

AC MACHINES FUNDAMENTALS

* Rotor and stator design, windings, poles, three-phase circuits, induced torque, winding insulation, AC machine power flows and losses

INDUCTION MOTORS

* Stator and rotor construction, synchronous speed, induced torque, rotor slip, equivalent circuit of an induction motor, induction motor construction
* Squirrel-cage rotors, wound rotors, synchronous speed, operating speed, slip, equivalent circuit, inrush current, losses and power-flow diagram, torque-speed characteristics, variation of torque-speed characteristics, induction generator
* NEMA classes of motors, control of motor characteristics, starting circuits

SPEED CONTROL OF INDUCTION MOTORS

* Speed control by changing the line frequency, voltage, rotor resistance, solid-state motor drives, motor protection, induction generator, motor ratings and specifications

MAINTENANCE OF MOTORS

* Characteristics of motors, enclosures and cooling methods, application data, design characteristics, insulation of motors, failures in three-phase stator windings, predictive maintenance, motor troubleshooting, diagnostic testing for motors, insulation resistance and polarization index

Day II

POWER ELECTRONICS, RECTIFIERS AND PULSE-WIDTH MODULATION INVERTERS

* Introduction to power electronics, power electronics components, the diode, the two-wire thyristor or PNPN diode, the three-wire thyristor or SCR, the gate turn off thyristor, the DIAC, the TRIAC
* The power transistor, the Insulated Gate Bipolar Transistor (IGBT)
* Power and speed comparison of power electronic components
* Basic rectifiers circuits, the half-wave rectifier, the full-wave rectifier, the three-phase half wave rectifier, the three-phase full-wave rectifier, filtering rectifier output
* Pulse circuits, a relaxation oscillator using a PNPN diode, pulse synchronization
* Voltage variation by AC phase control, AC phase control for a DC load driven from an AC source, AC phase angle control for an AC load, the effect of inductive loads on phase angle control
* Inverters, rectifiers, external commutation inverters, self-commutated inverters
* Pulse-Width Modulated (PWM) Inverters

VARIABLE-SPEED DRIVES

* Basic principles of AC Variable-Speed Drives (VSDs), constant torque region, constant power (extended speed) region
* Inverters, parts of an inverter, Pulse Width Modulated (PWM) inverters, Insulated Gate Bipolar transistors (IGBT’s), 2-level pulse width modulated inverter (PWM-2)
* Input power converter (rectifier), DC link energy, output IGBT inverter
* Input sources for regeneration or dynamic slowdown, dynamic breaking, regeneration, PWM-2 considerations
* Transients, harmonics power factor and failures, common failure modes, fault current limit, device explosion rating, device application
* Thyristor failures and testing, recognizing failed Silicon Controlled Rectifier (SCR)/Diode, testing of SCR’s/Diodes, comments about failure rates.
* AC drive applications issues, diode source current unbalance, AC power factor, AC input power changes with ac input voltage.
* IGBT switching transients, insulation voltage stress, motor winding voltage distribution
* Radiated Electromagnetic Interferences (EMI), cable terminating (matching) impedance, inverter output filter, extra insulation, cabling details for AC drives, cable details
* Motor, cable, and power system grounding.
* Motor bearing currents, motor shaft grounding brush, reduction of stator to rotor capacitance value, motor cable wiring practices
* Summary of application rules for AC drives: Selection criteria of variable speed drives, variable process speed, compressors and pumps, motor starting, regeneration, dynamometer, paper machine winder, dynamic breaking
* Maintenance, common failure modes, motor application guidelines.

BEARINGS

* Types of bearings, ball and roller bearings, materials and finish, sizes of bearings, types of rolling bearings, thrust bearings

LUBRICATION

* Viscosity of lubricants, variation of viscosity with temperature and pressure, viscosity index, non-Newtonian fluids, greases, VI improved oils, oils at low temperatures, variation of lubricant viscosity with use, oxidation reactions, physical reactions, housing and lubrication, lubrication of antifriction bearings
* Used oil Analysis: proper lube oil sampling technique, test description and significance, visual and sensory inspections, chemical and physical tests, water content, viscosity, emission spectrographic analysis, infrared analysis, total base number (TBN), total acid number (TAN), particle count, summary

VIBRATION ANALYSIS, PREDICTIVE MAINTENANCE AND DIAGNOSTIC TESTING

* Application of sine waves to vibration, resonance, use of filtering
* Vibration instrumentation, frequency domain, machinery example
* Vibration causes, forcing frequency causes, unbalance, misalignment, mechanical looseness, bearing defects, gear defects, oil whirl, blade or vane problems, electric motor defects, uneven loading, drive-shaft torsion
* Resonant frequency, vibration severity, a case history (motor shaft misalignment).
* Vibration in predictive maintenance: diagnostics (identifying the characteristic vibration patterns of common faults; looseness of anti-friction bearings, journal bearings and gears)

After Attending This Course You Will Be Able To:

* Learn about various types of motors, and variable speed drives
* Understand diagnostic testing and inspection, advanced fault detection techniques, critical components, and common failure modes of this equipment
* Study selection criteria, commissioning requirements, predictive and preventive maintenance, reliability, testing and cost
* Discover the maintenance required to minimize their operating cost and maximize their efficiency, reliability and longevity

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