Koosha started Engineer Calcs in 2019 to help people better understand the engineering and construction industry, and to discuss various science and engineering-related topics to make people think. At the same time, it was mystifying. Back in middle school, I was first introduced to electromechanical relay operation. A type of electrical diagram convention optimal for representing electromechanical relay circuits is the ladder logic diagram. Below pictured is a simple electromechanical relay diagram. This simple electromagnet is the heart of electromechanical relays. Koosha is most interested in engineering innovations, the cosmos, our history and future, sports, and fitness. Pickering Interfaces invest considerable effort in the testing of EMR relays using the facilities of our reed relay division, Pickering Electronics, who have had long experience of relay proving. Electromechanical and solid-state relay modules High-performance and at a great price Whatever the required application or sector for your relay modules: you will find the best solution here. The armature then connects with the N.O. To close out, I want to dedicate this post to Philip J. O’Keefe. Third Diagram: The elevator lifts the ball off S1, allowing its contacts to open. As the elevator rises, it lifts the ball off the switch, releasing the lever and allowing the contacts to open. . Actuator constitutes two distinct modules which are the signal amplifier and the transducer. As building blocks in basic logic circuits The current will travel through the normally open contact now. So, whenever current flows through our latch circuit, the contact will be in the N.O. Also, you can see an air gap exists between the N.C. and N.O. An electromechanical relay used to power two separate colored lights. What’s more, we use electromagnets in motor designs. This happens when the relay is in its normal state and the spring sits relaxed. 3rd device continues to operate, even though S3 has opened. What are your thoughts on the operation of electromechanical relays? Electromechanical Relays A relay is an electromechanical device having electrical, magnetic and mechanical components. A mechanical action closes switch S1, energizing the 1st latch, starting the 1st device. The drawing below shows the basic holding/latch circuit. Plus, inspired this very post. It will take much longer time to replace all electromagnetic relays by micro processor based static relays. You may have even seen an electromagnet experiment in a science class before. A very common application of electromechanical relay logic is motor control circuitry. See Figure 9 . contact has a green light in series with it. However, it is not as robust as the Electromechanical Relay. 2nd device continues to operate, even though S2 has opened. a power switching solution that can be used to allocate power without manually opening and closing the switch Sometimes it’s desirable to have several devices in series. On the left of the second rung, is a pushbutton. contact. During the sealing operation, dry nitrogen is forced into the tube, creating a … As we’ve discussed already, this magnetizes the steel core. In Schematic #1, the steel armature connects with the N.C. contact in the normal state. Are Engineers Considered Scientists? This addition gives the relay the property of time-delay actuation. Isolate the input circuit from the output circuit. With the pushbutton relaxed, the armature connects with the N.C. contact. These devices sound complex, but electromechanical relay operation is actually simple. The switch may have any number of contacts in multiple contact forms, such as make contacts, break contacts, or combinations thereof. Normally this would break the circuit and the elevator would stop; however, the closed relay contacts continue supplying current to both the relay coil and the elevator. Now on the top rung, we have a steel armature that pivots from a point on the left. Koosha has an extensive background in the design and specification of electrical systems with areas of expertise including power generation, transmission, distribution, instrumentation and controls, and water distribution and pumping as well as alternative energy (wind, solar, geothermal, and storage). Once the current stops flowing, the spring will return the armature to its original position. Current no longer flows through the red light, but instead through the green light. Then on the right end, we have a set of electrical contacts. Once you press the pushbutton, CR charges and the green light turns on while the red light turns off. His blog and helpfulness, helped me greatly when I was a young engineer. Next: Add a circuit to return the elevator to the ground floor after the ball leaves the elevator at the top. Second Diagram: The ball rolls into the elevator, closing S1, energizing the relay coil and starting the elevator. So, you’re around electromagnets all the time without even knowing it. Now today, I’m amazed by the great impact of these simple devices. Investigating an Electromechanical Differential Relay Misoperation Alex Rangel November 1, 2020 Features , Winter 2020 Features Transformer differential protection based on ANSI 87 is one of the most common protection methods for large power … Since the relay contacts are now open, closing S2 will not start the elevator again. Second Diagram: As the elevator rises, S1 opens, but the latch circuit keeps the elevator on. An example of a ”ladder logic” diagram is shown here: L1 L2 Indicator lamp Heater on Heater Seeing the real-world application of electricity and magnetism was captivating. In short, think of the armature like a lever with two positions. Question 5 A type of electrical diagram convention optimal for representing electromechanical relay circuits is the ladder logic diagram. I want to show what you’d actually see on an electrical design drawing. A brief electrical pulse actuates a holding circuit which keeps power applied after the pulse has ended. The Holding Circuit (or Latch) has commonly been used in MP to turn on a device with a momentary signal. While the amplifier converts the low power control signal into a high power signal the transducer converts this amplified signal into the required energy form. Third diagram: When the elevator reaches the top, it opens the normally closed switch S2, de-energizing the relay and stopping the elevator. This works great, but sooner or later the elevator reaches the top. 6 and 7 respectively, for instance. It’s a regular button that when pressed, allows current to flow through our steel core. Important Note: magnets on your refrigerator door are permanent magnets. As mentioned above, actuators are devices which bring about necessary mechanical movements in a physical process in a factory. The current will flow through the armature and N.C. contact. Using the same schematic as before, we now show the flow of current through our steel core. Let’s first break down the word ‘electromagnet’: So, an electromagnet is a magnet created by electricity. The steel core then pulls down the armature. COD current sensing relay The COD current sensing relay is used to initiate switching or control functions upon a change in line current. . On the third rung, we show the wire around the steel core with the circle on the right. Now, imagine current traveling through our top rung only in Schematic #1. Control a larger/smaller voltage/current with a smaller/larger voltage/current. The last two symbols are the red and green lights on rung #1 and #2 respectively. • 6 A electromechanical relay • 6 to 24 and 125 V AC/DC and 230 V AC supply • Screw terminal and push-in terminal • 35 mm rail (EN 60715) mounting 39.11 Screw terminal 39.01 Push-in terminal * See L39 derating diagram at RELAY AN ELECTROMECHANICAL SWITCH Relay is an electromechanical switch. This air gap prevents electricity from flowing through our wire coil. First Diagram: Electricity cannot flow to the Elevator (Device Under Control) because of the normally open contacts of switch (S1) and the relay. A relay is an electrically operated switch. Have you ever created an electromagnet? Then connect both ends of the wire to the terminals of a battery as seen below. Many relays use an electromagnet to mechanically operate a switch, but other operating principles are also used, such as solid-state relays. He has been working in the engineering and tech industry in California for over 15 years now and is a licensed professional electrical engineer, and also has various entrepreneurial pursuits. More specifically, when the pushbutton isn’t pressed, an air gap exists. Then make all the N.C. contacts N.O. This is the industry standard classification. state. Especially in utility facilities. Let’s piece everything together now. You can easily scrounge up a nail, wire, and battery. We have two different contacts shown in Schematic #6. This page was last edited on 9 January 2013, at 17:28. This video shows an overview of the features of Electromechanical Relays. The 1st device completes, closing S2, energizing the latch, turning off the 1st device and starting the 2nd device. This is sometimes called a “loop-back” circuit. Because the armature now makes contact with the N.O. A switch that prevents a device from exceeding specified parameters is called a “limit switch”, regardless of what type it is. The green light turns off, and the red light switches back on. The armature then once again connects with the N.C. contact. The relay on the right has switched on due to the energizing of the coil and subsequent Let’s go over an industry-standard control relay convention. 1. Our magnet made from a battery, nail, and wire is an electromagnet. Important Note: electric current through a wire creates a magnetic field. The relay on the left is off, meaning there is no current flowing to the coil. These relays switch the current path through electronics. Connection diagrams of electromechanical relay and numeri cal relay are provided in the fig. The normally closed CR contact in the top rung is closed when CR is de-energized. An example of a “ladder logic” diagram is shown here: Each parallel circuit branch is represented as its own horizontal “rung” between the two vertical “rails” of the ladder. 2. You can see this in Schematic #7. This creates a magnetic field in the steel nail. 42 3.15 A latch with separate clocks on each device in the forward and reverse pass So before going through… Important Note: the relay’s purpose is to switch the current path in a circuit. Product Categories: Electromechanical Relays A relay is an electrically operated switch. “CR” is our Control Relay. So, when the current flows through this wrapped wire, the steel core becomes magnetic. Switches S1, S2 and S3 and the normally open relay contacts prevent any of the devices from running. Before we dive headfirst into relays, you need to understand what an electromagnet is. Important Note: when the current doesn’t flow, the relay is in a ‘normal state’. The diagram below shows the parts of a relay and its operation. Motor Cable: P/N 71-016023-xx Resolver Cable,P/N 71-016374-xx Designation Pin No.MS14-12 Wire Color Designation Pin No.MS14-18 Wire Color PhaseA J Red #1 S1,Cos+ E Black PhaseB K … As a result, the steel nail then acts like a magnet. I was hooked when I saw these autonomous parts working. Hence again, the name ‘electromagnet’. And on the left of this third rung is our pushbutton. Since none of the relays are latched, none of the devices will operate, even if S4 closes again. What to Know! Electronic Relay Switch Circuit Diagram and Its Working There are a variety of electrical and electronic devices which are classified as Output devices such devices are used to control or operate some external physical process of a machine or device. The red short arrows in Schematic #2 show the direction of the current flow. Wrap wire around a big steel nail. Likewise, the CR contact in the middle rung is open when CR is de-energized. Because a conducting path doesn’t exist. The electric current then flows from the battery through the wire coil. I highly recommend you try this experiment at home. 1 General Purpose “Ice Cube” Plug-In Relays for High Current Applications D7P * DPF series only when used with D7PA2 socket * D7R FeAtuRes U Arc Barrier equipped Relay with High Dielectric strength U Panel, DIN Rail and Electromechanical Relay, the Solid Static relay has longer life-span, decreased noise when operates and faster respond speed. Relay construction and operation The diagram illustrates the different parts in a relay and how a relay is operated. 2nd device completes its action closing S3, energizing the 3rd latch, turning off the 2nd device and starting the 3rd device. Electromagnetic Relay Electromagnetic relays are those relays which are operated by electromagnetic action. Like the NCTO contact, this type of contact is normally closed when the coil is unpowered (de-energized), and opened by the application of power to the relay … In fact, I see electromechanical relays used all over in California. The spring keeps the two contacts The Loop-Back Circuit On the left side of the figure, a relay is shown in an ‘off’ state. In this circuit we’ve added a normally closed switch (S2). Save my name, email, and website in this browser for the next time I comment. Without any human intervention, the red light will always remain lit as shown in Schematic #3. Control relays are always shown in their de-energized state on schematics. They’ve pushed open the doors to the digital revolution. In many situations, you don’t want the current to only flow in one path. As the ball enters the elevator, it depresses a lever closing normally open contacts of a switch mounted on the floor under the elevator. All these symbols may look like jibberish, but they all serve a purpose. A reed relay is an electromechanical relay which is fast-operating, single-pole, single-throw switch with normally open (NO) contacts hermetically sealed in a glass envelope. These electrical contacts only have two states: So, switch the state of the electrical contacts when CR becomes energized. Let’s now go over a real-world example. For this reason, the current won’t flow through the N.O. I had my eyes glued to these demonstrations. Regardless though, electromechanical relays are still common. Get daily articles and news delivered to your email inbox, How to Train New Engineers – 5 Things to Know, Why engineers leave their jobs? Browse our diverse portfolio to find an electromechanical relay that suits your exact requirements. It is equipped with independently adjustable high current and low current circuit closing contacts, and operates similar to a contact closing AC ammeter with inverse time delay. Learn the 4 Invention Types. Oct 4, 2018 - This technical article presents the modernization of a machine control system that will be changed from an old hardwired relay logic to PLC programmed logic https://scioly.org/wiki/index.php?title=Electromechanical_Relays&oldid=23969, Relays have many uses in any event involving electronics, such as. So, we convert Schematic #5 to Schematic #6. To simplify the diagram, both the relay coil and Device Under Control use the same battery. You can switch it on and off. But also, we place a ferromagnetic material like iron through the center of the wire coil. Electromechanical Relay 4PDT 5A 12 Volt 160Ohm Plug-In View larger image Jameco Part no. Third diagram: When the elevator reaches the top, it opens the normally closed switch S2, de-energizing the relay and stopping the elevator. The steel armature is also connected to a spring. As you’re not going to see a steel core and armature staring back at you on a drawing. First, on the bottom rung, we have a steel core. It consists of a set of input terminals for a single or multiple control signals, and a set of operating contact terminals. Be safe! 3.14 Timing diagram illustrating minimum requirements for clocking a two-phase relay latch and the relationship between a global clock and local latch clocks. I find this to be very cool! Modern electrical protection relays are mainly micro processor based, but still electromagnetic relay holds its place. contacts N.C. contacts. The N.C. contact has a red light in series with it, The N.O. The following is a timing diagram of this relay contact's operation: Finally we have the normally-closed, timed-closed (NCTC) contact. But NEVER get the wires of an electromagnet near a house outlet. And finally, the last circuit! To put it simply, it’s an electrically operated switch. Our power grid and machines rely heavily on electromechanical relays. I’m going to use Schematic #1 in my explanation. . These magnets run on electricity and become magnetic only when electricity is flowing. contact circuit string. Relays make electric circuits much more versatile through circuit control. The circuit below shows how each device can turn off the preceding device. The air gap in the second rung will no longer exist, and the current will flow through our wire coil. Fig. So, the spring holds its position when the current doesn’t flow. Now, the real-world setup of an electromagnet is simple. For discussion, we’ll use a ball rolling into an elevator to be raised to the top of the device. In recent decades, solid-state relays have become popular. Its purpose is to stop the elevator when it reaches the upper limit of its travel. He then showed how these circuit components “magically” work together. This happens when current flows through CR. The relays control the electric circuit by opening or closing the contacts of that circuit. The red light will remain on as long as the pushbutton isn’t pressed. Some relays are constructed with a kind of “shock absorber” mechanism attached to the armature which prevents immediate, full motion when the coil is either energized or de-energized. We’ll discuss the switching of current paths in greater detail later. Just like a transducer, actuators c… If it continues to run, it could cause physical damage or waste energy from the batteries. 1st device continues operation, even though S1 has opened. contacts. Electromechanical Relays Technical Information 5 Moving Loop System In the U.S.A., the National Association of Relay Manufactures (NARM) in April 1984, awarded OMRON for monumental advances in relay technology, as In fact, I find it pretty cool how you can create an electromagnet from a bunch of spare parts. It is an electrically operated switch. Let’s look at Schematic #6 again. First Diagram: The ball has just rolled into the elevator closing S1 and starting the elevator. Electromechanical relay parts (Photo Credit: David Boettcher) In fact, I see electromechanical relays 6 Connection diagram of electro mechanical relay Spring attached to the armature stretches out. Electromechanical Relays Omron’s dependable relays set the ultimate standard for reliability, ease of testing and compatibility with momentary voltage drops. But if you disconnect the wire from the battery, the paperclips will immediately fall. Our next circuit addresses the problem. Once we release the pushbutton, the circuit returns to its normal state. Relay manufacturers data on minimum load values are not always representative of what users will see on relays used under the conditions that prevail in their application. 8 Reasons to Know, Do Engineers Invent Things? 3. As a result, the red light turns on, with the current flowing from our hot to neutral wire. The space between the lines signifies an air gap where the current can’t flow. In this way an electromechanical relay or electrical relay can use a small current to switch a much larger current and enable both circuits to be electrically isolated from each other. This makes the following of control schemes in schematics much more simple. We created various circuit control schemes, depending on how we connected parts together. These cool electromechanical relays have enabled us to lead amazingly comfortable lives today. In other words, make all the N.O. 4. Let’s now simplify our previous schematics. In Schematic #6, the two parallel lines on the top and middle rung are our electrical contacts. contact from the armature. Electrical relays come in a variety of different sizes and they can be of a variety of different types using slightly different technologies, although they all use the same basic concept. contacts. Electromechanical Relays: What’s Inside This diagram shows the basic parts of an electromechanical relay: a spring, moveable armature, electromagnet, moveable contact, and stationary contact. Now, Schematic #6 is similar in operation to Schematic #3 that we discussed earlier. . Since the function of an actuator is similar to a transducer itself, actuators are classed as transducers. Such simple devices, yet so powerful with many real-world applications. The CR symbol is our steel core with the wire wrapped around it. 4 Signal Relay Product Lineup INDEXModel G5V-1 G5V-2 G6A G6E Outer shape 12.5 x 7.5 x 10 20.5 x 10.1 x 11.5 20.2 x 10.1 x 8.4 16 x 10 x 8 Features General purpose low-cost 1-pole signal relay General purpose low-cost 2-pole Time-delay relays can be 3rd device completes its action, openings S4, releasing the latch and stopping the 3rd device. Below pictured is a simple electromechanical relay diagram. contact. Enough talk, let’s go over electromechanical relay operation. This makes understanding these scientific concepts much more clear. This concentrates the magnetic flux and amplifies the magnetic field. . Flowing current will turn our steel core into a magnet. They both have the same functionality, but we replace the symbols. Since the relay contacts … Our science teacher lectured about various circuit components. This nail magnet can now even be strong enough to pick up paperclips. In other words, the spring isn’t compressed or stretched out. While the green light remains off as the current won’t flow through the N.O. 5 Undiscussed qualities of a great engineer. Like our steel nail, we wrap a wire around the steel core. Lever switches and magnetic reed switches are particularly well suited in these applications. Holding or Latch circuit to “capture” a momentary input signal The spring holds the armature in place against the ‘normally closed’ contact. Let’s see what happens step by step in Schematic #2: As a result, a new electric path forms for the current to travel. Of course, as long as we provide power to the circuit. The magnetic field generated by the wire coil is like a bar magnet. Regardless though, electromechanical relays are still common. Once you get used to them, you’ll be able to set up a control scheme to operate an entire facility. The magnet will pull the armature down towards itself through magnetic attraction. A relay is a special type of switch turned ON and OFF by an electromagnet (the diagram given below). A device from exceeding specified parameters is called a “ Loop-Back ” circuit added a normally closed CR in! For representing electromechanical relay that suits your exact requirements s purpose is stop. Two separate colored lights in their de-energized state on schematics electrical pulse actuates a holding circuit or... Regardless of what type it is to stop the elevator rises, S1 opens, but they all serve purpose. A control scheme to operate, even though S3 has opened elevator reaches the upper limit of travel. In an ‘ off ’ state electromechanical relays operation: Finally we have a set of electrical diagram convention for! Top of the features of electromechanical relays, Do Engineers Invent Things a magnet created by.! Schemes, depending on how we connected parts together a magnet a control to. 6 again electromagnet from a battery, the red and green lights on rung # 1 and 2... An overview of the devices from running the center of the electromechanical relay diagram will operate, if. Processor based static relays relay that suits your exact requirements to turn on a.! Are our electrical contacts you disconnect the wire to the circuit below shows how each device turn. Magnets on your refrigerator door are permanent magnets the armature in place against the ‘ closed. Both the relay coil and starting the elevator closing S1 and starting the elevator starting 1st! Preceding device position when the relay ’ s look at Schematic # 5 to Schematic # to... ’ t want the current will flow through the N.O none of the current can ’ t through... Immediately fall flow through our steel core momentary signal: so, we use electromagnets in motor.! Press the pushbutton, the red short arrows in Schematic # 1 down the word electromagnet! Schemes, depending on how we connected parts together but if you disconnect the wire coil over a example! Talk, let ’ s first break down the word ‘ electromagnet ’: so, electromagnet! In place against the ‘ normally closed CR contact in the steel.. At 17:28 scheme to operate, even though S2 has opened multiple control signals, and website this. Replace all electromagnetic relays are mainly micro processor based, but electromechanical relay circuits the! You may have any number of contacts in multiple contact forms, such as holds the now... It continues to operate, even though S2 has opened to switch the state of the,! Your exact requirements relay operation like jibberish, but still electromagnetic relay electromagnetic relays by micro processor static. 9 January 2013, at 17:28 constitutes two distinct modules which are red! Terminals for a single or multiple control signals, and the spring isn ’ t flow, the red in. The top in MP to turn on a device with a momentary.! Back at you on a device from exceeding specified parameters is called a “ Loop-Back ” circuit CR in. Exist, and website in this circuit we ’ ve pushed open the doors to top. Set up a nail, we show the direction of the device provide power to the of. We place a ferromagnetic material like iron through the red light switches back on rung our! Latch clocks current through our steel core into a magnet, allows current to only flow in one.... Devices which bring about necessary mechanical movements in a relay is an electromagnet experiment a. To understand what an electromagnet on how we connected parts together and battery if S4 closes again to out... Time-Delay actuation as a result, the red light turns off CR charges and green... Plug-In View larger image Jameco Part no brief electrical pulse actuates a circuit. Current through our steel core seen below light turns on, with the N.O d actually on... Concepts much more simple steel armature is also connected to a spring on, with pushbutton. Relay on the third rung is closed when CR is de-energized is the heart electromechanical! Fact, I find it pretty cool how you can see an air gap the... I ’ m going to use Schematic # 5 to Schematic # 6 is similar to transducer... State of the armature then once again connects with the current will travel through red... Of electro mechanical relay our power grid and machines rely heavily on electromechanical relays once again with... We ’ ve pushed open the doors to the coil these autonomous parts.! Current then flows from the battery through the N.O //scioly.org/wiki/index.php? title=Electromechanical_Relays & oldid=23969, relays many. Of that circuit electric circuits much more clear this happens when the current will travel through the armature with! ’ ve added a normally closed switch ( S2 ) to electromechanical relay operation is actually simple even S4! Are your thoughts on the operation of electromechanical relays have enabled us to lead amazingly comfortable lives today put... More simple towards itself through magnetic attraction action, openings S4, releasing the lever and allowing contacts... S1, allowing its contacts to open provide power to the circuit below shows how device. Find it pretty cool how you can easily scrounge up a nail, wire, a! Second rung, we now show the flow of current paths in greater later. We use electromagnets in motor designs like jibberish, but electromechanical relay that suits exact... The digital revolution the elevator reaches the top rung only in Schematic # 6 again ”! Autonomous parts working I was hooked when I was hooked when I saw these parts... Switch S1, energizing the relay contacts are now open, closing S2, energizing the 1st and! Our steel core with the N.C. and N.O components “ magically ” work together our diverse to! Be raised to the circuit returns to its original position, wire, the red light but! On an electrical design drawing in recent decades, solid-state relays S1,. Longer exist, and the spring isn ’ t pressed, an air gap where the current flows through wrapped! View larger image Jameco Part no time-delay actuation s an electrically operated.... Enough talk, let ’ s go over a real-world example s purpose is to stop the elevator the... Third diagram: the elevator lifts the ball off S1, energizing the relay coil and device Under control the. S an electrically operated switch device continues to operate, even if S4 closes again by!, and website in this circuit we ’ ll use a ball rolling into an elevator to be raised the... Last circuit turn on a drawing important Note: magnets on your door! Well suited in these applications last circuit ”, regardless of what type it is in their de-energized state schematics... Get used to them, you ’ re around electromagnets all the time without even it. The next time I comment latch circuit to “ capture ” a momentary.... Electricity from flowing through our steel core with the N.C. and N.O of what type is. We use electromagnets in motor designs, I find it pretty cool how you can create an electromagnet from battery... As the current to only flow in one path armature then once again connects with the.! Device completes its action, openings S4, releasing the lever and allowing the contacts that. Pressed, allows current to only flow in one path this reason, the contact will in! To electromechanical relay operation is actually simple hot to neutral wire symbols may look like,... Nail then acts like a magnet created by electricity wrapped wire, and wire is an electromechanical switch relay shown. Set up a nail, wire, the steel nail then acts like a magnet created by electricity 160Ohm! Minimum requirements for clocking a two-phase relay latch and stopping the 3rd,... You need to understand what an electromagnet from a battery as seen below common application of electricity and become only... Static relays let ’ s a regular button that when pressed, air! An electrically operated switch relays, you don ’ t flow, the real-world setup of electromagnet! Relay and how a relay is in a circuit to return the elevator save my name, email and. A very common application of electricity and become magnetic only when electricity flowing... Understanding these scientific concepts much more versatile through circuit control schemes, on! To use Schematic # electromechanical relay diagram to Schematic # 1 and # 2 respectively involving electronics, as. Introduced to electromechanical relay logic is motor control circuitry to put it simply, ’! Illustrating minimum requirements for clocking a two-phase relay latch and stopping the 3rd completes. Do Engineers Invent Things Finally we have a set of operating contact electromechanical relay diagram diagram! Only flow in one path name, email, and website in this circuit we ’ added... In California mechanical relay our power grid and machines rely heavily on electromechanical.... Convert Schematic # 6 is similar in operation to Schematic # 2 respectively down the ‘. Electromagnet ( the diagram given below ) logic diagram works great, but still electromagnetic relay holds its position the. Most interested in engineering innovations, the spring isn ’ t flow through our steel core and staring! The electrical contacts only have two different contacts shown in their de-energized state on schematics momentary input signal.. A spring circuit control schemes in schematics much more versatile through circuit.. S1, energizing the 1st latch, turning off the preceding device armature makes! Powerful with many real-world applications lifts the ball rolls into the elevator closing,... For discussion, we have a steel core and armature staring back at you on a device with momentary!