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Figure 15--1 A typical set of push-button switches and selector switches used to operate a machine. (Courtesy of Rockwell Automation.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--2 An exploded view of a typical switch. Notice that the switch activation push button is shown above the panel where it is accessible to the operator, and the remainder of the switch, including rubber seals, and the switch contacts are shown below the panel. (Courtesy of Rockwell Automation.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--3 (a) Fork lever roller yoke limit switch. (b) Roller arm limit switch. (c) Top roller limit switch. (d) Wobble lever- actuated cat whisker limit switch. (e) Side roller limit switch. (Courtesy of Honeywell Micro Switch Division.)

Thomas E. Kissell�Industrial Electronics, 3e

(a)

(b)

(c)

(d)

(e)

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Figure 15--4 The electrical symbol for NO limit switch, NO held closed limit switch, NC limit switch, and NC held open limit switch.

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--5 Electrical symbols for pilot devices and other motor control devices. (Courtesy of SQUARE D COMPANY/GROUPE SCHNEIDER. “Square D Company/Groupe Schneider assumes no liability for accuracy of information.”)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--6 (a) NC pressure switch. (This switch may be referred to as an NC high-pressure switch.) (b) NO pressure switch. (This switch may also be referred to as an NO high-pressure switch.) (c) NC pressure switch. (This switch may be referred to as an NC low-pressure switch.) (d) NO pressure switch. (This switch may be referred to as an NO low-pressure switch.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--7 A ladder diagram of a control circuit and a load circuit.

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--8 An example of a wiring diagram that shows a control circuit and a three-phase motor in the load circuit. Notice the motor starter is shaded in the wiring diagram so that you can locate it and all of its terminals.

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--9 (a) A wiring diagram of a two-wire control circuit for a compressor motor. The compressor motor is controlled by a motor starter that is energized by one of two pressure switches. (b) A ladder diagram of the same circuit shown in the wiring diagram. In this circuit you can see a selector switch provides “hand” or “auto” control. Pressure switch A is in the circuit when the selector switch is in auto, and pressure switch B is in the circuit when the selector switch is in manual. (Courtesy of Rockwell Automation.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--10 (a) A typical three-wire control system. This control circuit gets its name because of the auxiliary contacts that are connected in parallel with the start button. The auxiliary contacts seal in the circuit to keep the coil energized after the start push button is released. (b) Ladder diagram of a three-wire control circuit. (Courtesy of Rockwell Automation.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--11 The wiring diagram for a three-wire control circuit with additional start and stop push buttons added to the circuit is shown at the top of this figure, and the ladder diagram of just the control circuit is shown at the bottom. (Courtesy of Rockwell Automation.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--12 A wiring diagram and a ladder diagram of a three-wire control circuit with an indicator lamp added to show when the motor starter coil is energized. (Courtesy of Rockwell Automation.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--13 An exploded view of a typical indicator lamp. Notice the lens is replaceable so different color lenses can be used. The field wiring is connected to a terminal section that allows the lamp to be changed when it is damaged without removing and replacing the wiring. (Courtesy of Rockwell Automation.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--14 A wiring diagram and ladder diagram of a forward and reverse motor starter. Notice that you can clearly see the interlock system in the ladder diagram. (Courtesy of Rockwell Automation.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--15 A drum switch. Notice the handle requires the operator to manually change the position of the switch from forward to reverse or to the off position. (Courtesy of Eaton Corporation Cutler-Hammer Products.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--16 (a) Contacts of a drum switch when it is switched to the reverse position. (b) Contacts of a drum switch when it is switched to the off position. (c) Contacts of a drum switch when it is switched to the forward position.

Thomas E. Kissell�Industrial Electronics, 3e

(a)

(b)

(c)

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Figure 15--17 (a) A single-phase AC motor connected to a drum switch. (b) A three-phase AC motor connected to a drum switch. (c) A DC motor connected to a drum switch. (Courtesy of Eaton Corporation, Cutler- Hammer Products.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--18 A ladder diagram of a forward and reverse jogging circuit. Notice the interlock between the forward push buttons and the reverse push buttons so that you can-not energize the forward and reverse motor starters at the same time. (Courtesy of Rockwell Automation.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--19 A wiring diagram of a for-ward and reverse jogging circuit. Notice that this diagram shows the location of the jog push button and the forward motor starter and re-verse motor starter. (Courtesy of Rockwell Automation.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--20 Motor starters are sequenced so that motor starter 1 must be on before motor starter 2 is started. (Courtesy of Rockwell Automation.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--21 Three types of level switches. Applications and electrical diagrams of these switches are shown in the next figure. (Courtesy of SQUARE D COMPANY/GROUPE SCHNEIDER. “Square D Company/ Groupe Schneider assumes no liability for accuracy of information.”)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--22 (a) A float and rod are used with the level switch to turn it on and off. (b) A closed flow switch is mounted at the specific level that is controlled. (c) A float is attached to one end of a cable and a weight is attached to the other end. When the float moves up or down, the switch is activated. (Courtesy of SQUARE D COMPANY/GROUPE SCHNEIDER. “Square D Company/Groupe Schneider assumes no liability for accuracy of information.”)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--23 Example of a typical pressure switch that is used as a pilot device. (Courtesy of SQUARE D COMPANY/GROUPE SCHNEIDER. “Square D Company/Groupe Schneider assumes no liability for accuracy of information.”)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--24 A graph of inrush current for a 208-volt, 5-hp motor.

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--25 (a) Example graph of short-circuit current. (b) Example of graph of current when a circuit breaker is used to protect against short-circuit current. (c) Example graph of current when a fuse is used to protect against short-circuit current.

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--26 (a) Cutaway picture of single-element fuse before it has developed an open. (b) Cutaway picture of a single-element fuse that shows an arc established at the middle neck-down section when the current is too large. (c) The middle neck-down section has completely opened after the cur-rent exceeded the maximum level. (d) Arcs are established at each neck-down section of the fuse when severe overcurrent is experienced. (e) All the neck-down sections develop opens when the severe overcurrent continues. (Courtesy of Bussmann.)

Thomas E. Kissell�Industrial Electronics, 3e

(a)

(b)

(c)

(d)

(e)

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Figure 15--27 (a) A cutaway picture of a dual-element fuse. Notice the time-delay element consists of a spring-loaded trigger mechanism that is held in place by solder. When the current is sufficient, it will melt the solder and the spring will open the fuse section. (b) The fuse is in the process of opening during a slow overcurrent. (c) The slow overcurrent section of the fuse has opened. (d) The short-circuit section of the fuse sustains a short-circuit current. (e) The short-circuit link on the right side of the fuse has opened after sustaining a short-circuit current. (Courtesy of Bussmann.)

Thomas E. Kissell�Industrial Electronics, 3e

(a)

(b)

(c)

(d)

(e)

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Figure 15--28 Types of cartridge and plug fuses available for use in industrial circuits. (Courtesy of Bussmann.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--28 (Continued)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--29 List of enclosure types provided by the National Electric Manufacturers Association (NEMA). (Courtesy of Rockwell Automation.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--30 Examples of NEMA-rated enclosures. (Courtesy of Rockwell Automation.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--31 American Wire Gauge (AWG) wires sizing table provided by the National Electrical Code (NEC). (National Electrical Code®, and NEC®, are registered trademarks of the National Fire Protection Association, Quincy, MA 02269.)

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--32 A typical lockout device that can accept multiple padlocks.

Thomas E. Kissell�Industrial Electronics, 3e

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Figure 15--33 Typical tag-out tag.

Thomas E. Kissell�Industrial Electronics, 3e