The document discusses energy conservation and management as it relates to electric motors. It provides an introduction to electric motors, describing their key components and types including induction motors, direct current motors, and synchronous motors. It then discusses motor efficiency criteria and types of losses in electric motors. Methods for calculating losses and selecting an appropriate motor are described. Formulas for synchronous speed, slip, and motor efficiency are also presented.
Electric motors(Bureau of Energy Efficiency) .pptx
1. Energy Conservation and Management
Electric Motors
Presented by:
Ram Bhute (58)
Guided by:
Prof. Sujit Arun Patil
Department of Mechanical Engineering
Shri Ramdeobaba College of Engineering and
Management, Nagpur
2. Content
• Introduction
• Types of Motor
• Efficiency criteria
• Types of Losess
• Method of calculating losses
• Motor selection
• Conclusion
3. Introduction
• Converts electrical energy to mechanical energy
• Key components
a) Stator
b) Rotor
c) Bearing
d) Frame
• Types of electric motor
a) Induction Motor
b) Direct Current motor
c) Synchronous Motor
4. Induction Motor
Applications: pumps, blowers and fans, compressors, conveyers and production lines
The induced magnetic field of the stator winding induces a current in the rotor. This induced rotor current
produces a second magnetic field, which tries to oppose the stator magnetic field, and this causes the rotor to
rotate
5. Direct-Current Motors
Applications: high starting torque / smooth acceleration over broad speed range
Direct-Current motors, as the name implies, use direct-unidirectional, current.
6. Synchronous Motor
Applications: robot actuators, ball mills, watches, record players, and turntables
AC power is fed to the stator of the synchronous motor. The rotor is fed by DC from a separate source. The rotor magnetic
field locks onto the stator rotating magnetic field and rotates at the same speed.
8. Motor Efficiency (η)
• Ratio of the mechanical energy delivered to electrical input
• Power factor (PF)
• Power Factor = Cos φ =
𝑘𝑊
𝑘𝑉𝐴
9. Types of Losses
• Fixed losses
• Magnetic Core Losses (Iron Losses)
• F&W Losses
• Variable losses
• Resistance Losses (I2R Losses)
Fixed losses consist of magnetic core losses and friction and
windage losses. Magnetic core losses (sometimes called iron
losses) consist of eddy current and hysteresis losses in the
stator. They vary with the core material and geometry and with
input voltage. Friction and windage losses are caused by
friction in the bearings of the motor and aerodynamic losses
associated with the ventilation fan and other rotating parts.
Variable losses consist of resistance losses in the stator and in
the rotor and miscellaneous stray losses. Resistance to current
flow in the stator and rotor result in heat generation that is
proportional to the resistance of the material and the square of
the current (I2 R). Stray losses arise from a variety of sources
and are difficult to either measure directly or to calculate, but
are generally proportional to the square of the rotor current.
10. Field Test for Determining Efficiency
• No Load Test
• Observations: Power, Current, Frequency, Voltage and Power Factor Meter
• F&W and core losses = No load power (watts) - (No load current)2 × Stator
resistance
• Stator and Rotor I2R Losses
• Stray Load Losses
11. Motor Selection
• Required Torque
• Duty or Load Cycle (use TEFC)
• Operating conditions
• Frequency
• Reliability
• Inventory and spare parts
• Price
