Book | Electric Motor Control, 9th Edition by Stephen L. Herman

Electric Motor Control, 9th Edition by Stephen L. Herman

Book's Contents

Unit 1: General Principles of Electric Motor Control. 

Unit 2: Fractional and Integral Horsepower Manual Motor Starters. 

Unit 3: Magnetic Line Voltage Starters.

Unit 4: Symbols. 

Unit 5: Interpretation and Application of Simple Wiring and Elementary Diagrams. 

Unit 6: Push Buttons and Control Stations.

Unit 7: Relays.

Unit 8: Contactors.

Unit 9: Timing Relays. 

Unit 10: Pressure Switches and Regulators. 

Unit 11: Float Switches.

Unit 12: Flow Switches.

Unit 13: Limit Switches and Proximity Control. 

Unit 14: Phase Failure Relays.

Unit 15: Solenoid Valves. 

Unit 16: Temperature Switches.

Unit 17: Two-Wire Controls.

Unit 18: Three-Wire and Separate Controls.

Unit 19: Hand-Off-Automatic Controls.

Unit 20: Multiple Push Button Stations.

Unit 21: Interlocking Methods for Reversing Control. 

Unit 22: Sequence Control.

Unit 23: Jogging (Inching) Control Circuits.

Unit 24: Time-Delay, Low-Voltage Release Relay. 

Unit 25: The Motor and Starting Methods. Unit 26: Primary Resistor-Type Starters. 

Unit 27: Auto transformer Starters. 

Unit 28: Part Winding Motor Starters. 

Unit 29: Automatic Starters for Star-Delta Motors.
Unit 30: AC Solid-State Reduced Voltage Controller. 

Unit 31: Controllers for Two-Speed, Two-Winding (Separate Winding) Motors. 

Unit 32: Two-Speed, One-Winding (Consequent Pole) Motor Controller.

Unit 33: Four-Speed, Two-Winding (consequent Pole) Motor Controller. 

Unit 34: Wound Rotor Motors and Manual Speed Control. 

Unit 35: Push Button Speed Selection. 

Unit 36: Automatic Acceleration for Wound Rotor Motors. 

Unit 37: Automatic Speed Control for Wound Rotor Motors.

Unit 38: Solid-State Adjustable Speed Controller for AC Wound Rotor Motors.

Unit 39: Synchronous Motor Operation.

Unit 40: Push Button Synchronizing.

Unit 41: Timed Semiautomatic Synchronizing.

Unit 42: Synchronous Automatic Motor Starter. 

Unit 43: About DC Motors.

Unit 44: Use of Reduced Voltage for Starting. 

Unit 45: Across-the-Line Starting.

Unit 46: Compensating and Definite Time Control Starting. 

Unit 47: Solid-State Adjustable Speed Control.

Unit 48: Plugging.

Unit 49: Electric Brakes. 

Unit 50: Dynamic and Regenerative Braking. 

Unit 51: Electric and Electronic Braking.

Unit 52: Direct Drives and Pulley Drives.

Unit 53: Gear Motors. 

Unit 54: Variable-Frequency Mechanical Drives.

Unit 55: AC Adjustable Frequency Drives.

Unit 56: Magnetic Clutch and Magnetic Drive.

Unit 57: DC Variable-Speed Control - Motor Drives. 

Unit 58: Programmable and Motion Control.

Unit 59: Motor Startup and Troubleshooting Basics.

Unit 60: Troubleshooting Techniques.

 

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Tutorial | Design of lighting schemes

A well designed lighting scheme must be satisfied the following conditions:
-Provides adequate illumination.
-Provides sufficiently uniform distribution of light all over the working-plane.
-Provides a comfortable color lighting of the seeing objects for our eyes.
-Avoids glare and hard shadows.
In addition to the above conditions, economic cost must be satisfied.

The following factors are considered while designing the lighting scheme:
1-Illumination level:
This is the most vital factor because a sufficient illumination is the basic means by where we are able to see our surroundings; it is the task of illumination to give objects a distributed brightness.
Objects which are seen for longer duration of time require more illumination than those for casual work. Similarly moving objects require more illumination than those for stationary object.
2-Uniformity of illumination:
The human eye adjusts itself automatically to the brightness within the field of vision. If there is a lack of uniformity, pupil or iris of the eve has to adjust more frequently and thus fatigue is caused to the eye and productivity is reduced. It has been found that visual performance is best if the range of brightness within the field of vision is not greater than 3:1 which can be achieved by employing general lighting in addition to localized lighting.
Apart from the consideration of causing fatigue, local lighting without using matching general lighting creates psychological feeling of loneliness, gloom and unfriendliness. The modem trend is thus towards "localized lighting plus general lighting" and towards the adoption of general lighting oriented towards the working surface" especially in mass production factories, offices, drawing offices, shops etc.
3-Color of light:
The appearance of the body color entirely depends upon the color of the incident light. In general the composition of the light should be such that the color appears natural i.e its appearance by artificial light is not appreciably different from that by day light.
 

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4-Shadows:

In lighting installations, formation of long and hard shadow causes fatigue of eyes and therefore is considered to be a short coming. Complete absence of shadows altogether again does not necessarily mean an ideal condition of lighting installations.

5-Mounting height:

The mounting height will largely be governed by the type of building and type of lighting scheme employed. In the case of direct lighting, in rooms of large floor area, the luminaries should be mounted as close to the ceiling as possible.

Lowering them not only will make the illumination less uniform, but will also bring them more into the field of vision, thus increasing the glare, without causing an appreciable increase in the coefficient of utilization. In the usual case of small rooms with high ceilings, there is something to be gained by lowering the luminaries.

6-Spacing between luminaries:

Correct spacing is of great importance to provide uniform illumination.

With fluorescent luminaries it is good practice to aim at a value of unity for this ratio, and to set an upper limit of ¾ In this case of tungsten lamps combined with focusing reflectors, it is good practice to aim at a horizontal spacing between rows approximately equal to the height of the ceiling above the working plane, and in no case should the horizontal spacing exceed 1 ½ times this height.

height of the ceiling above the working plane, and in no case should the horizontal spacing exceed 1 ½ times this height.

7-Color of surroundings walls:

The illumination in any room depends upon the light reflected from the walls and ceiling. White walls and ceiling reflect more light as compared to colored ones.

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