Pressure Switch Explained | Types of Pressure Switches
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▶ Want to learn industrial automation? Go here: http://realpars.com ▶ Want to train your team in industrial automation? Go here: http://realpars.com/business ▶ Check out the full blog post over at https://realpars.com/pressure-switch ⌚Timestamps: 00:00 - Intro 01:19 - What is a pressure switch? 02:11 - Pressure switch vs pressure transmitter 02:44 - Pressure switch types 04:30 - Pressure switch symbols 05:41 - Pressure switches in action 06:06 - Deadband ============================= In this video, we’re going to talk about different types of pressure switches and how they operate. Depending on who you talk to, pressure switches fall under the Pressure Sensor category. Some people will tell you that a Pressure Sensor is a device for pressure measurement of gases or liquids. Included in this Pressure Sensor category along with pressure switches are pressure transducers, pressure transmitters, and pressure senders, among other names. This can be a bit confusing because in the world of instrumentation and process control we define a Sensor as a device that detects changes in physical, electrical, or chemical properties and produces an electrical output in response to that change. And just to add even more confusion, the terms pressure sensor, pressure transducer, and pressure transmitter are unfortunately used interchangeably in the industrial world. A Pressure switch is a two-part device consisting of a sensing transducer and an electrical switch. The electrical switch opens and closes at a specific pressure often referred to as the Setpoint. Depending on the switch and the vendor, the switching pressure setpoint may be fixed or adjustable. A transducer is a device that converts one form of energy to another. So, the transducer part of the pressure switch is the piece that comes in contact with the process under test. Then somehow, the transducer has to operate the electrical switch. Vendors produce pressure switches using different types of transducers and different types of switches. A pressure transmitter has a transducer just like a pressure switch. That’s where the similarity ends. The output of a Pressure Transmitter is an analog electrical voltage or a current signal representing 0 to 100% of the pressure range sensed by the transducer. There are two different types of pressure switches: electromechanical and solid-state. Electromechanical pressure switches all have traditional-style mechanical switches with moving parts. There are a variety of different types of transducers that are used to mechanically operate the switch such as Diaphragm and Bourdon type. – Diaphragm switches use a metal diaphragm to operate the switch. – Bourdon tube switches use a bourdon tube to operate the switch. Solid-state pressure switches have no moving parts. Electrical switching is accomplished by operating a semiconductor device such as a bipolar junction transistor or a Field Effect transistor. A typical transducer used on a solid-state pressure switch is a strain gauge Wheatstone Bridge. The term Electronic Pressure Switch is slowly replacing the term Solid-State Pressure Switch. The Electronic Pressure Switch is solid-state but much more versatile. It offers options such as Programmable functions, LED displays, multiple and adjustable output switch configurations such as normally open, normally closed, or both. As with other electrical devices, there are several different symbols used on schematics to represent pressure switches. All pressure switches on a schematic diagram will be shown in their De-energized condition, or in other words, the condition they would be in sitting on a shelf. Deadband is the difference between the setpoint and the point where the switch re-actuates. ============================= If you want to learn more, you might want to review two of our other articles: What is a Pressure Sensor? https://realpars.com/pressure-sensor Pressure Transmitter Explained | Working Principle https://realpars.com/pressure-transmi... ============================= Missed our most recent videos? Watch them here: https://realpars.com/plc-timer https://realpars.com/factory-acceptan... https://realpars.com/hmi-display ============================= To stay up to date with our last videos, make sure to subscribe to this YouTube channel: http://bit.ly/realpars ============================= Follow us on Facebook: https://www.facebook.com/therealpars Follow us on Twitter: https://twitter.com/realpars Follow us on LinkedIn https://www.linkedin.com/company/real... Follow us on Instagram https://www.instagram.com/realparsdotcom #RealPars #Pressure_Switch #industry
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PID is an acronym for Proportional, Integral, and Derivative. A PID controller is a device that is used to control a process. The controller can be a physical, stand-alone device or a control block found in a PLC function database. The PID portion of the controller is a series of numbers that are used as adjustments in order to achieve your objective. A very simple example of a PID controller would be the regulation of a heating and air conditioning system in a home. Although there is a lot more to the controller than this example, this will give you a basic idea of the purpose of a device like this. Consider that you have the temperature in your home set to 70 degrees Fahrenheit. This setting would be called the Setpoint or “SP” for short. The current reading from the thermostat is 68 degrees Fahrenheit. This term is the Process Variable or “PV”. The heating or cooling unit is the Control Variable or “CV”. The Control Variable may also be referred to as the Manipulated Variable or “MV”. There are different types of control action and for the temperature control in the house, the controller action is a direct-acting device meaning that the calculations are Setpoint minus Process Variable (SP-PV). In our house example, we have a SetPoint of 70 and the Process Variable is 68 degrees Fahrenheit. For this control when we subtract the Process Variable from the SetPoint we see that we have a value of 2. This result is called the Error or “E” in our process. In the simplest terms, our house is too cool and the controller tells the heating unit to turn on. Remember, we are trying to get to 70 degrees. The unit will remain ON until the Error in our process becomes zero. Now let’s say that someone opens a window in the house and it’s very cold outside. This disruption in the process is called Disturbance. The factors in this process control may be: - “How fast do we want the temperature to reach the setpoint”. - “What could disturb our process”? Clearly, there are many factors that can impact our processes and adjusting our controller’s parameters is how we deal with those factors. In an industrial plant, since there are many factors that we need to consider, we need a robust controller that takes our parameters into account and does hundreds of calculations to determine where the process is and where it needs to go. Say we need to control gas flow through a pipe. The Setpoint of gas flow is calculated based on a calculation of some factors. This Setpoint can change at any time based on the parameters used in the calculation. We will control this flow based on a modulating valve. In this case, the more open the valve, the more gas allowed to flow. The requested position of the valve is our Control Variable. Downstream of this modulating valve we have a flow meter that will measure the gas flowing through the pipe, this is our feedback or our Process Variable. Let’s take a step back and talk about the parameters that we will be adjusting for our control. First, the PID term, as stated earlier, stands for Proportional, Integral, and Derivative. These parameters can be used individually or collectively. Meaning, you can have just a proportional controller, a proportional and integral, a proportional and derivative, or of course a proportional, integral, and derivative controller. To sum it all up, we, as control engineers, need to control processes and in order to do that, we use devices available to us in order to facilitate that function. The stand-alone and integrated PID controller is the most widely used device for that purpose.

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The star-delta starter is a common method used in starting heavy three-phase motors. Although there are other new ways of starting heavy-duty motors, you can still benefit from learning this popular traditional method as an automation engineer. Here is the basic idea. When you turn on a three-phase motor, in the first few minutes of starting the motor, it draws up to 4 times more current than the rated current. This huge amount of current can damage the motor windings and also the electrical network. In the star-delta starter, we first run the motor in star connection and then after a few minutes, when the motor gains sufficient speed, we’ll switch the connection to Delta. In star connection, the current that the motor draws is one-third of the rated current so by running the motor in star connection we can reduce the startup current. ========================== To stay up to date with our last videos and more lessons, make sure to subscribe to this YouTube channel: http://goo.gl/Y6DRiN ============================= Like us on Facebook: https://www.facebook.com/therealpars/ Follow us on Twitter: https://twitter.com/realpars Follow us on LinkedIn: https://www.linkedin.com/company/realpars
The programmable logic controller, or PLC, is a special purpose computer. It has no display, no keyboard, no printer, no hard drive, and hides in the control panel out on the factory floor, but it is still a computer. Initially, the PLC was a replacement for panels of relays, devices that turn on and off. Making a machine run using relays as logic was time-consuming and challenging, and making a change in the logic or the operation of the machine was almost as complicated as starting over.
In this two-part video series, you will learn how to wire a 2-wire DC sensor, like a switch or a contact, to a PLC input card. You will also learn what a 2-Wire Discrete sensor is and recognize some of the common types of 2-Wire Discrete sensors. DC sensors can be used to indicate the state of a device or a process to the PLC program. Knowing these input states can allow the PLC program to make decisions, such as, when to start or stop a pump. Discrete DC Sensors, or discrete Direct Current sensors, operate in a circuit with a battery or other power source, commonly known as a power supply. A power supply is placed in an electrical circuit to provide power to the connected devices, like a switch, or a lamp. DC power supplies are referred to by their voltage and capacity, indicated by how many amperes they can supply. The more amperes a power supply can deliver, the larger and more expensive they generally are. In DC PLC circuits, the power supply almost always supplies 24 Volts DC to the connected devices.

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