2015 elec ch2補充

Figure 11–11(a) Graphical illustration of relay hysteresis. As current is increasing, the switching occurs

when the pull-in value is reached. As current is decreasing, the switching occurs when the drop-out value is reached. (b) The essential parts of an electromagnet relay. Hysteresis is due to p g y y

the gap between the armature and the magnet core.

Timothy J. MaloneyModern Industrial Electronics, Fourth Edition

Copyright ©2001 by Pearson Education, Inc.

Upper Saddle River, New Jersey 07458All rights reserved

Figure 1–2A relay logic circuit in which the relay coil is controlled by input devices, namely a limit switch and a pressure switch.




Figure 1–3A relay logic circuit in which relay coils are controlled by the contacts of other relays.




Figure 1–4(a) Physical layout of a conveyor/classifying system. (b) Top view of the diverting zone, showing the positions of the four diverting gates and the four chute limit switches.




Figure 1–5Control circuitry for the conveyor/classifying system, with the logic performed by magnetic relays.




Figure 1–6(a) The AND logic function performed by relay circuitry and by solid-state circuitry. (b) The OR function performed by relay circuitry and by solid-state circuitry.




Figure 1–7Schematic symbols of the five basic logic gates. A NOT gate is often called an inverter.




Figure 1–8Control circuitry for the conveyor/classifying system of Fig. 1–4, with the logic performed by solid-state logic gates.




Figure 1–13Output amplifiers for amplifying low-power logic signals into high-power output signals.




Figure 1–14(a) Output amplifier using a power transistor to control the current through the output device. (b) Output amplifier using a relay contact to control the current through the output device.




Figure 2–19(a) Simple relay circuit with a time-delay contact. (b) Motor power circuit associated with the relay control circuit in part (a).




Figure 2–20(a) Physical layout of a wagon being filled from a hopper. (b) Simple relay control circuit, illustrating the use of a time-delay contact to allow the powder to drain out of the supply tube into the wagon before the wagon is moved.




2015 elec ch2補充

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