PRINCIPLES AND APPLICATIONS OF ELECTRICAL ENGINEERING THIRD EDITION

PRINCIPLES AND APPLICATIONS OF ELECTRICAL ENGINEERING THIRD EDITION 16 Principles of Electromechanics Mc. Graw-Hill 1 GIORGIO RIZZONI © The Mc. Graw-Hill Companies, Inc. 2000

PRINCIPLES AND APPLICATIONS OF ELECTRICAL ENGINEERING THIRD EDITION Figure 16. 2 Charge moving in a constant field f u B q Mc. Graw-Hill 2 GIORGIO RIZZONI © The Mc. Graw-Hill Companies, Inc. 2000

PRINCIPLES AND APPLICATIONS OF ELECTRICAL ENGINEERING THIRD EDITION Figure 16. 17(a) Magnetic circuit with air gap i l N l r 2 0 l air gap l Mc. Graw-Hill 3 GIORGIO RIZZONI © The Mc. Graw-Hill Companies, Inc. 2000

PRINCIPLES AND APPLICATIONS OF ELECTRICAL ENGINEERING THIRD EDITION Figure 16. 17(b) Equivalent representation of magnetic circuit with an air gap 2 3 1 g + _ 4 5 Mc. Graw-Hill 4 GIORGIO RIZZONI © The Mc. Graw-Hill Companies, Inc. 2000

PRINCIPLES AND APPLICATIONS OF ELECTRICAL ENGINEERING THIRD EDITION Figure 16. 38 i + v – Fixed N = 700 fe Movable Mc. Graw-Hill 5 GIORGIO RIZZONI x © The Mc. Graw-Hill Companies, Inc. 2000

PRINCIPLES AND APPLICATIONS OF ELECTRICAL ENGINEERING THIRD EDITION Figure 16. 40 A solenoid i Fixed structure N turns lg a 2 a x a Mc. Graw-Hill a a x= 0 Nonmagnetic bushing material ( r 1) Movable plunger Spring 6 GIORGIO RIZZONI © The Mc. Graw-Hill Companies, Inc. 2000

PRINCIPLES AND APPLICATIONS OF ELECTRICAL ENGINEERING THIRD EDITION Figure 16. 41 a a Ag x Plunger Mc. Graw-Hill 7 GIORGIO RIZZONI © The Mc. Graw-Hill Companies, Inc. 2000

PRINCIPLES AND APPLICATIONS OF ELECTRICAL ENGINEERING THIRD EDITION Figure 16. 45 Circuit symbols and basic operation of relays NO “ Make, ” or normally open (NO) relay or single-pole, single throw, SPSTNO “ Break, ” or normally closed (NC) relay or single-pole, single throw, SPSTNC NC NC “Break, make” or single-pole, double throw SPDT (B-M), or “ transfer ” NO NC CT “ Make, break, ”or “ make-before-break ” or single-pole, double throw SPDT (M-B), or “ transfer, ” or “ continually transfer ” NO i I Basic operation of the electromechanical relay: The (small) coil current i causes the relay to close (or open) and enables. (interrupts) the larger current, I On the left: SPSTNO relay (magnetic field causes relay to close). On the right: SPSTNC relay (magnetic field causes relay to open). Mc. Graw-Hill 8 GIORGIO RIZZONI © The Mc. Graw-Hill Companies, Inc. 2000