emergency stop button

How Do Emergency Stop Buttons Work?

An emergency stop button is a fail-safe control switch installed on most types of machinery to protect people and equipment from harm. Sometimes called a kill or E-stop switch, it ensures that machinery can be instantly turned off in any threatening circumstances.

They’re fitted in a location that’s easy to access and operate in any emergency, even if you’re wearing gloves. The button is usually required to be red, with a yellow housing, background or bezel to draw attention. Designs that light up in darker environments are also available. Common E-stop buttons come with IP54 ingress protection, but it’s also possible to get a waterproof version that can be certified to IP65 or IP67.

Emergency stop buttons come in many shapes, sizes and colours, as long as these are highly visible, and conform to international standard ISO 13850. This specifies that an emergency stop switch must be designed in a shape that’s easy to operate in emergencies. They’re often prominently labelled with the words STOP or EMERGENCY.

Emergency stop buttons are normally red and mushroom-shaped, sometimes with directional indicators if the switch is to be turned. The mushroom head is usually considered the best choice to comply with industrial safety requirements and IEC standards. These state that as well as being safe and reliable, emergency stop buttons must be convenient for operators to use with one hand.

How Do Emergency Stop Buttons Work?

The switch is a safety mechanism specifically designed to protect both the operator and the integrity of the machinery itself in the event of an emergency shutdown. The emergency stop switch can immediately shut off the machinery when it can’t be closed down in the normal way.

Emergency stop buttons on machinery are wired in series with their control circuit. They function with a direct operation mechanism set in the Normally Closed (NC) position for the electrical contacts. Options are available for switches with one or two NC contacts. When you push the button or mushroom head for an emergency stop, the switch breaks the electrical circuit and prevents electricity from passing through it. This causes the equipment to immediately stop functioning. If the power must be stopped differently, you can connect emergency stop buttons to a controller.

Emergency stop buttons are self-holding switches that stay in place until you release the contacts and allow the machinery to start up again. The release of the button must only take place under strictly authorised procedures when it’s confirmed that the machinery or equipment is entirely safe to operate again. Sometimes, switches are designed for two-hand control, to ensure that both an operator’s hands are safely out of the way during any hazardous procedure.

The most common emergency stop switches function according to the way the actuator works:

  • Pull release – in this type of button, you push the actuator in to stop the machine and pull the actuator back to release it.

  • Twist release – in this type you push the actuator in to stop the equipment and twist the actuator to release it.

  • Key release – here you push the actuator in to stop the machinery and use a key to release it. You’ll usually insert the key into the head of the button. This type of emergency stop button release is ideal for restricting its operation only to authorised personnel, especially in high-risk environments.

Where Do You Find Emergency Stop Buttons?

You’ll find emergency stop buttons in all sectors of industry, on a wide variety of premises including commercial and public facilities as well as industrial environments. They must be clearly visible to anyone who has to use them as part of their job. You might also find several emergency stop buttons on the same machine if it has several parts that have to be stopped independently. Such instances might include escalators, lifts, lifting equipment, packaging machinery, etc.

Whether machines require an emergency stop button depends on the regulations and standards governing machinery in different industries or countries. Very basic-level machines may not require equipment to have an emergency stop system. In any event, a safety risk assessment must be carried out before installing and using any machine (or part of it). Once such a risk assessment has been carried out and its hazard level (or performance level) determined, you must take the appropriate measures required to reduce the risk.

According to the European machine safety standards ISO 13849 and ISO 12100, there are three categories of standards, labelled A, B and C. The generic safety standards apply to a wide range of machinery from category B. These are further subdivided into four incremental hazard levels: 1, 2, 3, and 4. Each one relates to a particular aspect of safety such as required distances, noise or temperature levels, or types of safeguard. The safety control circuit must also meet these standards, so it will first be put into category B, then subdivided into hazard levels 1, 2, 3 and 4.

A Key Contribution To Safety

Emergency stop buttons are a crucial component of any automated system, where there may be a hazard to health and safety. Their purpose is to stop machines and equipment instantly if there’s any risk of injury, or a dangerous interruption in the workflow, like jamming. It’s often referred to as a push-button safety switch because it’s there to avert harm to people, equipment or the work processes.

In the process of risk assessment and compliance, emergency stop buttons also help to reduce or eliminate existing hazards. In this way, they supply a key contribution to machine and employee safety. In most countries, it’s legally required for different types of machinery to provide an emergency stop function. A thorough system assessment is critical to selecting the right emergency stop button for your application.

Reference:

https://www.rowse-automation.co.uk/blog/post/how-do-emrgency-stop-buttons-work

demo-attachment-457-person-with-long-curly-hair-PZ99QM2@2x

Women in Business

When, while the lovely valley teems with vapor around me, and the meridian sun strikes the upper surface of the impenetrable foliage of my trees, and but a few stray gleams steal into the inner sanctuary, I throw myself down among the tall grass by the trickling stream; and, as I lie close to the earth, a thousand unknown plants are noticed by me: when I hear the buzz of the little world among the stalks, and grow familiar with the countless indescribable forms of the insects and flies, then I feel the presence of the Almighty, who formed us in his own image, and the breath of that universal love which bears and sustains us, as it floats around us in an eternity of bliss; and then, my friend, when darkness overspreads my eyes, and heaven and earth seem to dwell in my soul and absorb its power, like the form of a beloved mistress, then I often think with longing, Oh, would I could describe these conceptions, could impress upon paper all that is living so full and warm within me, that it might be the mirror of my soul, as my soul is the mirror of the infinite God!

O my friend — but it is too much for my strength — I sink under the weight of the splendor of these visions! A wonderful serenity has taken possession of my entire soul, like these sweet mornings of spring which I enjoy with my whole heart. I am alone, and feel the charm of existence in this spot, which was created for the bliss of souls like mine.

I am so happy, my dear friend, so absorbed in the exquisite sense of mere tranquil existence, that I neglect my talents. I should be incapable of drawing a single stroke at the present moment; and yet I feel that I never was a greater artist than now.

When, while the lovely valley teems with vapor around me, and the meridian sun strikes the upper surface of the impenetrable foliage of my trees, and but a few stray gleams steal into the inner sanctuary, I throw myself down among the tall grass by the trickling stream; and, as I lie close to the earth, a thousand unknown plants are noticed by me: when I hear the buzz of the little world among the stalks, and grow familiar with the countless indescribable forms of the insects and flies, then I feel the presence of the Almighty, who formed us in his own image, and the breath of that universal love which bears and sustains us, as it floats around us in an eternity of bliss; and then, my friend, when darkness overspreads my eyes, and heaven and earth seem to dwell in my soul and absorb its power, like the form of a beloved mistress, then I often think with longing, Oh, would I could describe these conceptions, could impress upon paper all that is living so full and warm within me.

Diversity in the Workplace

When, while the lovely valley teems with vapor around me, and the meridian sun strikes the upper surface of the impenetrable foliage of my trees, and but a few stray gleams steal into the inner sanctuary, I throw myself down among the tall grass by the trickling stream; and, as I lie close to the earth, a thousand unknown plants are noticed by me: when I hear the buzz of the little world among the stalks, and grow familiar with the countless indescribable forms of the insects and flies, then I feel the presence of the Almighty, who formed us in his own image, and the breath of that universal love which bears and sustains us, as it floats around us in an eternity of bliss; and then, my friend, when darkness overspreads my eyes, and heaven and earth seem to dwell in my soul and absorb its power, like the form of a beloved mistress, then I often think with longing, Oh, would I could describe these conceptions, could impress upon paper all that is living so full and warm within me, that it might be the mirror of my soul, as my soul is the mirror of the infinite God!

O my friend — but it is too much for my strength — I sink under the weight of the splendor of these visions! A wonderful serenity has taken possession of my entire soul, like these sweet mornings of spring which I enjoy with my whole heart. I am alone, and feel the charm of existence in this spot, which was created for the bliss of souls like mine.

I am so happy, my dear friend, so absorbed in the exquisite sense of mere tranquil existence, that I neglect my talents. I should be incapable of drawing a single stroke at the present moment; and yet I feel that I never was a greater artist than now.

When, while the lovely valley teems with vapor around me, and the meridian sun strikes the upper surface of the impenetrable foliage of my trees, and but a few stray gleams steal into the inner sanctuary, I throw myself down among the tall grass by the trickling stream; and, as I lie close to the earth, a thousand unknown plants are noticed by me: when I hear the buzz of the little world among the stalks, and grow familiar with the countless indescribable forms of the insects and flies, then I feel the presence of the Almighty, who formed us in his own image, and the breath of that universal love which bears and sustains us, as it floats around us in an eternity of bliss; and then, my friend, when darkness overspreads my eyes, and heaven and earth seem to dwell in my soul and absorb its power, like the form of a beloved mistress, then I often think with longing, Oh, would I could describe these conceptions, could impress upon paper all that is living so full and warm within me.

Plan Your Business

When, while the lovely valley teems with vapor around me, and the meridian sun strikes the upper surface of the impenetrable foliage of my trees, and but a few stray gleams steal into the inner sanctuary, I throw myself down among the tall grass by the trickling stream; and, as I lie close to the earth, a thousand unknown plants are noticed by me: when I hear the buzz of the little world among the stalks, and grow familiar with the countless indescribable forms of the insects and flies, then I feel the presence of the Almighty, who formed us in his own image, and the breath of that universal love which bears and sustains us, as it floats around us in an eternity of bliss; and then, my friend, when darkness overspreads my eyes, and heaven and earth seem to dwell in my soul and absorb its power, like the form of a beloved mistress, then I often think with longing, Oh, would I could describe these conceptions, could impress upon paper all that is living so full and warm within me, that it might be the mirror of my soul, as my soul is the mirror of the infinite God!

O my friend — but it is too much for my strength — I sink under the weight of the splendor of these visions! A wonderful serenity has taken possession of my entire soul, like these sweet mornings of spring which I enjoy with my whole heart. I am alone, and feel the charm of existence in this spot, which was created for the bliss of souls like mine.

I am so happy, my dear friend, so absorbed in the exquisite sense of mere tranquil existence, that I neglect my talents. I should be incapable of drawing a single stroke at the present moment; and yet I feel that I never was a greater artist than now.

When, while the lovely valley teems with vapor around me, and the meridian sun strikes the upper surface of the impenetrable foliage of my trees, and but a few stray gleams steal into the inner sanctuary, I throw myself down among the tall grass by the trickling stream; and, as I lie close to the earth, a thousand unknown plants are noticed by me: when I hear the buzz of the little world among the stalks, and grow familiar with the countless indescribable forms of the insects and flies, then I feel the presence of the Almighty, who formed us in his own image, and the breath of that universal love which bears and sustains us, as it floats around us in an eternity of bliss; and then, my friend, when darkness overspreads my eyes, and heaven and earth seem to dwell in my soul and absorb its power, like the form of a beloved mistress, then I often think with longing, Oh, would I could describe these conceptions, could impress upon paper all that is living so full and warm within me.

Travel and Work During Spring

When, while the lovely valley teems with vapor around me, and the meridian sun strikes the upper surface of the impenetrable foliage of my trees, and but a few stray gleams steal into the inner sanctuary, I throw myself down among the tall grass by the trickling stream; and, as I lie close to the earth, a thousand unknown plants are noticed by me: when I hear the buzz of the little world among the stalks, and grow familiar with the countless indescribable forms of the insects and flies, then I feel the presence of the Almighty, who formed us in his own image, and the breath of that universal love which bears and sustains us, as it floats around us in an eternity of bliss; and then, my friend, when darkness overspreads my eyes, and heaven and earth seem to dwell in my soul and absorb its power, like the form of a beloved mistress, then I often think with longing, Oh, would I could describe these conceptions, could impress upon paper all that is living so full and warm within me, that it might be the mirror of my soul, as my soul is the mirror of the infinite God!

O my friend — but it is too much for my strength — I sink under the weight of the splendor of these visions! A wonderful serenity has taken possession of my entire soul, like these sweet mornings of spring which I enjoy with my whole heart. I am alone, and feel the charm of existence in this spot, which was created for the bliss of souls like mine.

I am so happy, my dear friend, so absorbed in the exquisite sense of mere tranquil existence, that I neglect my talents. I should be incapable of drawing a single stroke at the present moment; and yet I feel that I never was a greater artist than now.

When, while the lovely valley teems with vapor around me, and the meridian sun strikes the upper surface of the impenetrable foliage of my trees, and but a few stray gleams steal into the inner sanctuary, I throw myself down among the tall grass by the trickling stream; and, as I lie close to the earth, a thousand unknown plants are noticed by me: when I hear the buzz of the little world among the stalks, and grow familiar with the countless indescribable forms of the insects and flies, then I feel the presence of the Almighty, who formed us in his own image, and the breath of that universal love which bears and sustains us, as it floats around us in an eternity of bliss; and then, my friend, when darkness overspreads my eyes, and heaven and earth seem to dwell in my soul and absorb its power, like the form of a beloved mistress, then I often think with longing, Oh, would I could describe these conceptions, could impress upon paper all that is living so full and warm within me.

gis

Gas Insulated Switchgear (GIS)

Gas-insulated electrical switchgear (GIS) is a type of compact switchgear assembly used in high-voltage electrical systems. It is designed to provide reliable and efficient operation in a limited space, making it suitable for both indoor and outdoor installations.

Here are some key characteristics and components of gas-insulated electrical switchgear:

1.    Gas Insulation: GIS utilizes sulphur hexafluoride (SF6) gas as the primary insulating medium. SF6 is an excellent electrical insulator and offers superior arc quenching properties. It enables the switchgear to have a compact design compared to traditional air-insulated switchgear.

2.    Metal Enclosure: The switchgear is housed in a metal enclosure that provides mechanical strength and protection against environmental influences. The enclosure is designed to contain the SF6 gas under high pressure.

3.    Circuit Breakers: GIS incorporates circuit breakers for interrupting the electrical current flow. These circuit breakers can handle high voltages and fault currents and are typically of the gas-blast or puffer type.

4.    Busbars: Busbars are conductive bars used to distribute electrical power within the switchgear. In GIS, the busbars are enclosed in a metal enclosure and surrounded by SF6 gas.

5.    Disconnectors and Earthing Switches: Disconnectors and earthing switches are used to isolate and ground specific sections of the switchgear. They provide a means for safe maintenance and repair work.

6.    Instrument Transformers: To measure electrical quantities such as current and voltage, instrument transformers, such as current transformers (CTs) and voltage transformers (VTs), are employed. These transformers provide scaled-down and isolated signals to protection relays and meters.

7.    Monitoring and Control Systems: GIS often incorporates advanced monitoring and control systems to supervise the switchgear’s condition and operation. These systems enable remote monitoring, diagnostics, and fault detection, enhancing the reliability and maintenance of the switchgear.

Benefits of Gas Insulated Electrical Switchgear:

a. Compact Design: GIS offers a significant space-saving advantage over traditional air-insulated switchgear. This makes it suitable for installations where space is limited or expensive, such as urban areas.

b. Enhanced Safety: The gas insulation of GIS reduces the risk of internal arcing and minimizes the potential for electrical accidents. The SF6 gas has excellent arc-quenching properties, allowing for faster interruption of faults.

c. High Reliability: GIS is designed for high reliability and can operate in extreme environmental conditions. The sealed enclosure protects the switchgear from dust, moisture, and other contaminants.

d. Improved Maintenance: GIS requires less maintenance compared to air-insulated switchgear. The gas insulation is stable and does not degrade over time, reducing the need for regular maintenance activities.

e. Easy Expansion: GIS systems are modular and can be easily expanded or modified to accommodate future load growth or system changes.

It’s important to note that due to the high global warming potential (GWP) of SF6 gas, efforts are underway to minimize its usage and develop alternative insulation technologies for switchgear applications. These alternatives aim to reduce environmental impact while maintaining the performance and safety characteristics of gas-insulated switchgear.

nosmoke

Low Smoke Cables

Low smoke cables, also known as LSZH cables (Low Smoke Zero Halogen) or LSOH cables (Low Smoke and Fume), are a type of cable designed to minimize the emission of smoke and harmful gases in the event of a fire. These cables are commonly used in environments where the safety of personnel and equipment is a primary concern, such as commercial buildings, residential complexes, transportation systems, and data centers.

Here are some key characteristics and benefits of low smoke cables:

1.     Low Smoke Emission: Low smoke cables are made with insulation and jacket materials that produce minimal smoke when exposed to high heat or fire. This is important because smoke generated during a fire can obstruct visibility, making it difficult for people to evacuate a building and for emergency responders to access the affected areas.

2.     Zero Halogen: In addition to reducing smoke emissions, low smoke cables are also designed to minimize the release of toxic and corrosive gases. They are manufactured using materials that have zero halogen content, such as polyethylene (PE) or thermoplastic polyolefin (TPO). Halogen-based materials, such as PVC (polyvinyl chloride), can release toxic gases when burned, which can be harmful to people and can damage sensitive equipment.

3.     Flame Retardant: Low smoke cables have flame-retardant properties, meaning they are designed to resist the spread of fire along the cable. The insulation and jacket materials used in these cables are formulated to self-extinguish when the heat source is removed, helping to prevent the fire from spreading and reducing the risk of fire-related damage.

4.     Safety and Health Considerations: The use of low smoke cables helps protect the safety and health of individuals in the event of a fire. By minimizing smoke and toxic gas emissions, these cables can improve visibility during evacuations, reduce the risk of inhalation of harmful substances, and facilitate emergency response efforts.

5.     Regulatory Compliance: Low smoke cables often comply with specific industry standards and regulations related to fire safety, such as the IEC 60332 standard for flame propagation, IEC 61034 for smoke density, and IEC 60754 for acid gas emission. Compliance with these standards ensures that the cables meet recognized safety requirements.

It’s important to note that low smoke cables are typically more expensive than standard cables due to the specialized materials used in their construction. The decision to use low smoke cables should be based on a risk assessment of the environment and the specific safety requirements of the installation.

Reference:

LinkedIn: Patronics Services

industryrelay

How To Choose Relay

Choosing a relay that’s suitable for your application requires a thorough understanding of the relay’s characteristics. Once you’ve found an appropriate relay, you can confirm its suitability and prove it in the actual operating environment where you’ll be using it.

There are several principles that you can apply to guide your selection, according to the separate parts of the relay, namely:

  • Contact

  • Coil

  • Performance

  • Use environment

  • Shape and installation

  • Other

For each part of this analysis, there are several principles to apply. These include the primary parameters you need to determine for each part, plus any influencing factors.

Contact

  • Contact load – AC, DC, size, type (inductive or resistive)

  • Contact form – NO, NC or conversion, several groups of contact pairs

  • Electrical durability – frequency of use, number of expected actions

  • Contact material – what material

  • Contact resistance – size, test conditions

You should also take into consideration influencing factors such as ambient temperature, whether the contact and contact material match and whether the action in AC loads is synchronised with the load. The relay mustn’t exceed the specified maximum current value and should be tested and confirmed in operation. Many contacts have a gold-clad layer, which performs better on medium and small loads.

When determining whether the contact load is adequate for your use application, you must confirm the size of the load and its type, as different loads operate under different steady-state values. Unless stated otherwise, the specified load is usually resistive. Different contact materials are used for different load types or ranges, even for the same type of relay.

Unless stated otherwise, electrical durability is usually shown as a nominal value, measured under operating frequency, certain temperature, rated load and load ratio. This value will differ for other load types and switching frequencies. The electrical durability of loads above 2A is usually greater for flux- and dust-proof relays than those encapsulated in plastic. If it’s possible in your environment, you can improve the relay’s service life by using dust- and solder-proof circuit breakers.

Coil

  • Rated voltage – size, direction, AC or DC

  • Action voltage – influence of size and power fluctuation

  • Release voltage – influence of size and power fluctuation

  • Maximum allowable voltage – size, time

  • Coil resistance – size, input power consumption

  • Coil temperature rise – what is the quantity, red insulation grade

Influencing factors are ambient temperature, power fluctuations and drops in electric voltage when driven by a semiconductor. You must confirm that the rated voltage can be supplied by the working circuit to the relay coil for the relay to work reliably. If the relay is driven by a transistor, there will be an associated voltage drop. This means the voltage reaching the relay coil will be below that specified for the drive circuit.

It’s sometimes possible to apply the maximum allowable voltage to the coil for a short time. This can reduce the relay action time, but you must ensure the relay doesn’t overheat or get damaged. If the relay is polarised, you’ll need to confirm the coil voltage’s polarity. You must also select the appropriate coil resistance for the relay to work reliably so that the working circuit can supply the relay with the appropriate nominal coil power consumption.

Performance

  • Packaging method – open, dust cover, plastic package, flux-proof

  • Dielectric strength – size, location

  • Insulation resistance – size, location

  • Impact resistance – size, stability or strength

  • Anti-vibration performance – size, stability or strength

Additional influences include the relay’s environmental conditions and security requirements. The various packaging methods have different requirements for the relay’s post-processing, to ensure its reliability. Choose the correct insulation resistance and dielectric strength for your application, to prevent the line from suffering short circuits, breakdown, etc. The same applies to the impact resistance and anti-vibration performance parameters, so the relay doesn’t fail during use.

Use Environment

  • Ambient temperature – high or low, time

  • Atmosphere – temperature, presence of harmful gases

The packaging method, insulation class and service life may also influence these factors. The relay usually works normally when the ambient temperature is within the range specified by the manufacturer. If the use environment is dusty, with high humidity or condensation, you should choose plastic-encapsulated relays. Dust contamination will soon cause relay contacts to fail, while high humidity and condensation accelerate corrosion in the relay’s structure.

Use sealed relays in environments containing silicone, because silicone accelerates relay contact failure. You should test and prove in use that plastic packaged relays work effectively in any environment containing harmful gases like H2S, SO2, NO2 etc. The dust cover and flux-proof type can’t be used in this kind of environment, but in a normal ambient atmosphere the dust- or flux-proof relays work better. This is because they offer greater electrical durability than plastic-packaged relays.

Shape And Installation

  • Shape – shape size, shape height

  • Outlet form – PCB, plug-in, QC, screw fixed

  • Welding method – manual, reflow, wave soldering, etc, and whether to clean

  • Installation clearance – gap, close

Influencing factors include the installation method and size requirements. The external dimensions of relays are created with specific tolerances, so you should design the circuit and installation clearance according to the maximum specified size. Ensure that the relays you choose can be reflow soldered if that’s what your application demands. Normal relay terminals are designed to be lead-free, with a recommended soldering time of two to five seconds at 240 to 260 Degrees. Choose the outlet’s shape and installation method to match the actual configuration of your relay’s application.

Other

  • Safety certificate – TUV, UL, VDE, CQC, depending on area

  • Special requirements and circumstances – customer request

As a general rule, VDE and TUV certification apply in Europe, while UL/CUL certification applies to North America. But most countries recognise all these certifications, owing to their international authority.

Applying The Principles To Relay Selection

Knowing how to choose a relay will save you time and money in breakdowns and failures. Follow the various principles of selection, then match the appropriate relay parameters and functions to the requirements of your application. It’s wise to bench-test your relays to confirm that you made the right choice and to prove them in operation to be sure they’re working optimally.

Reference:

https://www.rowse-automation.co.uk/blog/post/how-to-choose-relay