Unit 1 basic principles of motor controls different manufacturers of control devices, as well as books about motor controls, use different methods of showing the control circuit wiring. Shown here is a contactor for a threephase electric motor, installed on a panel as part of an electrical control system at a municipal water treatment plant threephase, 480 volt ac power comes in to the three normallyopen contacts at the top of the contactor via screw terminals. Motor contactor or starter coils are typically designated by the letter m in ladder logic diagrams. A contactor rated at 75 horsepower at 480 volt ac 3phase power is shown here, both assembled and with the top cover removed to reveal the three sets of highcurrent electrical switch contacts.
Wiring diagram book a1 15 b1 b2 16 18 b3 a2 b1 b3 15 supply voltage 16 18 l m h 2 levels b2 l1 f u 1 460 v f u 2 l2 l3 gnd h1 h3 h2 h4 f u 3 x1a f u 4 f u 5 x2a r. Contactors electromechanical relays electronics textbook. Relays are typically integrated into a logic circuit together with other relays and. Ac reversing manual starters and manual motor starting switches. In addition to the simplicity which they offer in project engineering, panel building. With a protection diode he can run that all day long. This is a glimpse of a course on plc programming course level1. Selection tools provide logical filters in product groups. For every motor, some form of electrical control is required, from simple onoff to more complex variable speed applications. Motor control devices encompass simple manual controllers, motor contactors and starters, drives and soft starters.
An entire book could be written on the principles and practices of good. Automaticnonautomatic transfer switch, contactor type 3. Jan 26, 2018 network analysis van valkenburg pdf author by. Applying some logic, you can conclude that the faster the contact closes, the sooner the arc is extinguished, and the longer the life expectancy of the. Emergency stop control conforms to stop category 0 of iec602041. Beginning with the basic principles of electrical logic, the author guides you through each step of the design of a sequencing logic system, including. Automationdirects ebooks here is a collection of automationdirects ebooks filled with information and references to deepen your understanding of everyday industrial automation topics. A computational logic acm monographs series includes bibliographic references and index. Continuous motor operation with a momentary start switch is possible if a normallyopen sealin contact from the contactor is connected in parallel with the start switch so that once the contactor is energized it. Electrical symbols, mechanical books, maintenance management and more. A computational logic university of texas at austin. However, this is not to suggest that logic is an empirical i. Typical electrical drawing symbols and conventions.
Plcs differ from office computers in the types of tasks that they perform and the hardware and software they require to perform these tasks. The computer program scanned the inputs and turned on or off relay coils to control machine logic similar to the logic above. For example, in figure b1, the control wiring from the startstop pushbutton station runs to the actual connection points 1, 2, and 3. The auxiliary contact is often used in a relay logic circuit, or for some other part of the motor control scheme, typically switching 120 volt ac power instead of the. Pdf programmable logic controller plc in automation. Yet, it is possible for someone besides a logic student to read this book. Raymond bradley norman swartz department of philosophy simon fraser university hackett publishing company. They are used in large quantities for the indirect control of motors, valves, clutches and heating equipment. Various types of automatic and manual control circuits can be designed to start the motor circuit. This video explains the basic concept of contactor and relay. Motor control circuits ladder logic electronics textbook.
Whether youre an industry beginner or have years of experience in the field, we guarantee there is something of value for you in these e books. Contacts and coils are discrete programming elements, dealing with boolean 1 and 0. Ratings of a contactor are given according to the pole of the contactor. Combinational logic circuits sequential logic circuits how digital logic gates are built using transistors design and build of digital logic systems. C contactor a threephase starter b singlephase starter type 25 nonreversing contactors and starters c306 27 nonreversing starters xtob 30 nonreversing starters c440 eol 65 reversing contactors c 2 5 d n a 2 1 5 a a 1 6 1 8 4 contactor frame size a compact, singlepole b compact, twopole c compact, singlepole w. Contactor for a threephase electric motor, installed on a panel as part of an electrical control system. The coil energizes the contactor, moving the contacts into position. Contactors and relays perform the same task of switching a circuit. Contactors control the electric current to the motor. In his case, the contactor hes using is a 24vdc coil which has an inrush and sealed rating of 9w 375ma.
Use safety relay module that conforms to safety category 3 of iso8491 or higher. The siemens stl language was a computer language similar to assembler capable of. In this straightforward, easytoread guide, bill bolton has kept the jargon to a minimum, considered all the programming methods in the standard iec 1 in particular ladder programming, and presented the subject in a way that is not device specific to ensure. Relays a relay is defined as an electrically controlled device that opens and closes electrical contacts, or activates and deactivates operation of other devices in the same or another electrical circuit. This transfer can be automatic or manual, depending upon the type of transfer. Also, in saying that logic is the science of reasoning, we do not mean. One contactor may have several auxiliary contacts, either normallyopen or normallyclosed if required. Each phase switch contact is actually a series pair of contacts that make and break simultaneously with the actuation of a ferrous armature attracted. Contactors and relays 5 5 contactor relays contactor relays contactor relays are often used in control and regulating functions. And to do that, we need to first understand boolean math and logic gates. What is the difference between a contactor and a relay. Ive never blown an output running a contactor off of a plc output.
So now that we have a understanding of what ladder logic is, we can dig a little deeper into how ladder instructions work. Contacts and coils in plc ladder logic plc training. A treatment of subjects in the field of electric networks or circuits which are considered as a foundation in electrical engineering and occur at either the start or intermediate level. Most of the diagrams in this book are shown in two ways. Programmable logic controller is an industrially hardened modular computer which. According to their rating, contactors are classified into the following. In addition to the simplicity which they offer in project engineering, panel building, commissioning and maintenance, the high. Sample circuits according to safety categories 52 safety concepts book use emergency stop pushbutton switch s1 that conforms to iec6094755 or iec6094751, iso850. In digital circuitry, however, there are only two states. All things plc, rockwell plc, even plc ladder logic simulator.
Two types of relay technology are available, mechanical and solid state. Typically in industrial relay logic circuits, but not always, the operating voltage for the. There is a wiring diagram and adjacent to it a line diagram. Last week we talked about the standard din numbers used on relays and the incredible utility they represent.
The auxiliary contact is often used in a relay logic circuit, or for some other part of the motor control scheme, typically switching 120 volt ac power instead of the motor voltage. If you see from the application point of view, you would have seen contactors placed in control panels of industrial motors or other heavy loads. From the logic of design to startup, operation and maintenance, this reference covers all aspects of wiring, relay logic, programmable logic controllers, and a host of electrical control applications and challenges youll encounter on the job. In general contactors are intended to control higher levels of current. Since the semantics of clausal logic is defined in its own terms, without reference to the. Free engineering software and engineering books pdf. Contactor relays are often used in control and regulating functions.
Digital systems, number systems and codes, boolean algebra and switching functions, representations of logic functions, combinational logic design, combinational logic minimization, timing issues, common combinational logic circuits, latches and flipflops, synchronous sequential circuit. Digital electronics part i combinational and sequential. If your roommate picked up the book and thumbed through it, they would not immediately become a logic student. No part of this wiring manual may be reproduced in any form.
Like a contactor, overload protection is a building block of starters. Find the top 100 most popular items in amazon books best sellers. Terminal 86 supplies power to the relays internal electromagnet. Abb control secrl 2 20010619 the abb range of a the abb range of a contactorscontactors a 9, a 12, a 16 a 26, a 30, a 40 a 50, a 63, a 75 a 95, a 110 a145, a185 a210, a260, a300 af400, af460 af580, af750. Rather, logic is a nonempirical science like mathematics. Digital logic circuits lecture pdf 19p this note covers the following topics. This is the introduction to plcs for which baffled students, technicians and managers have been waiting. Automating manufacturing systems industrial ebooks. Ladder logic is the logic plcs were originally invented to emulate. Rather, the term, contactor is used to describe a type of device that is used very much in the same manner as a relay. Free logic circuits books download ebooks online textbooks. In understanding ladder logic we touched on the origins of ladder logic, its structure and execution. Digital logic circuits pdf slides 50p download book. Course structure 11 lectures hardware labs 6 workshops.
Each contact in a ladder diagram plc program represents the reading of a single bit in memory, while each coil represents the writing of a single bit in memory. In any circuit with a din relay, without looking at a wiring diagram, you know that. It also depends on factors like fault withstand current, coil voltage and so on. The world of electronics was initially dominated by analogue signalsthat is, signals representing a continuous range of values. Fused control circuit transformer and control relay. The method of analysis 180 the objects of philosophical analysis 180 three levels of analysis 181 the idea of a complete analysis 183 the need for a further kind of analysis 184 possibleworlds analysis 185 degrees of analytical knowledge 187 3. Instead, take a few moments to see if there is an obvious problem. Wiring diagram book a1 15 b1 b2 16 18 b3 a2 b1 b3 15 supply voltage 16 18 l m h 2 levels b2 l1 f u 1 460 v f u 2 l2 l3 gnd h1 h3 h2 h4 f u 3 x1a f u 4 f u 5 x2a r power on optional x1 x2115 v. Since a contactor should last for years, dont automatically replace one that fails with an identical unit. Line diagrams are included because their use is becoming more widespread and we believe it is advantageous to learn to use them. A programmable logic controller plc, also referred to as programmable controller, is the name given to a type of computer commonly used in commercial and industrial control applications. Contactor relays contactor relays contactor relays are often used in control and regulating functions.