What is an Interlock? An interlock is a type of device that is used to prevent undesirable conditions in machines, which may include mechanical or electronic systems or devices. In almost all applications, it is utilized to aid in preventing machines from causing harm to the machine itself or to the operators.
- In some cases, interlocks are also used to prevent corrosion.
- An interlock can help prevent damage in equipment as well as injury to operators.
- For instance, household equipment like microwave ovens have interlock switches that disable the magnetron if the door is opened.
- Also, washing machines have the capacity to prevent its spinning if the lid is left open.
In its broader applications, interlocks promote device safety, particularly in industrial facilities. Interlocks can offer protection to employees. Typical examples of devices that require this mechanism include hammers, robots and presses. Interlocks can be sophisticated, like photodetectors or infrared beams, or can be simply switches.
- In some cases, interlocks can be purely mechanical, such as in firearms’ internal safety, preventing firing pin release if the chamber is not closed properly.
- In device operations such as hand-fed cutters and pressers, the utilization of interlocks or buttons to activate the device lessens the possibility of causing harm to its operator.
Interlocks can also be used for corrosion control. For instance, many industrial valves have interlock seals to prevent leakage and corrosion. Share this Term : What is an Interlock?
- 1 What is the purpose of an interlock?
- 2 What is an interlock on a P&ID?
- 3 What is the difference between switch and interlock?
- 4 What is the best interlock?
- 5 Why is it important that guards are designed with interlocks?
- 6 What are the stages of interlocks?
- 7 What material is interlock?
- 8 What are the different types of boiler interlocks?
What is the purpose of an interlock?
An interlock is a feature that makes the state of two mechanisms or functions mutually dependent. It may be used to prevent undesired states in a finite-state machine, and may consist of any electrical, or mechanical devices or systems.
What is an interlock on a P&ID?
Interlock: – An Interlock is in essence a ‘self resetting’ Trip. Interlocks are not deemed safety related and can be used for on/off control. Interlocks are normally initiated by the DCS or PLCs, however if an Interlock is deemed to be safety related it may, depending upon SIL rating, be implemented in the SIS or a Hardwired system.
An interlock will force a device or devices to a pre-determined state e.g. Close valve, stop motor, etc. Once a device or devices have been forced to a pre-determined state by the action of an Interlock they will remain in that state until the initiating cause returns to a ‘healthy’ condition, the Interlock will then be automatically removed.
Under normal circumstances it shall be possible to ‘override’ Interlocks for operational reasons or ‘defeat’ them for maintenance or other reasons.
What are the three types of interlocks?
Types of Interlocks Interlocks and interlock systems can be classified into three main groups, based on the type of interconnection between the interlocks. These three groups or types are: mechanical, electrical, and key interlocks. Each of these types has its advantages when properly designed and applied.
What is the difference between protection and interlock?
Protections & Interlocks in power plants
Interlocks: Are the programmed or hardwired control systems to protect systems and improve the operation reliability. Protections: Are the programmed or hardwired control systems to protect the equipments, man power and systems from failure/harm. The interlock and protection system is used to ensure safety of equipment and personnel as well as smooth & trouble free operation of the plant
This system initiates automatic corrective actions to stabilize the unit quickly. The protection scheme is developed to trip the equipment automatically with or Class A trip involves a serious electrical fault like differential, stator earth fault etc.
And is considered to be the most dangerous in terms of the shock on the unit. Since it involves serious electrical faults, connections from both generator and the HV bus is immediately switched off to limit the damage at the fault point and also to isolate the healthy system. Hence the unit (turbine, generator and boiler) has to be tripped without time delay.
Alarm & buzzers are generally used to alert the operator. POWER PLANT PROTECTIONS & INTERLOCKS AND THEIR SIGNIFICANCE
|Sl No.||Interlock description||Significance|
|1||FD & SA fan trip/stop on tripping of ID fans||To avoid furnace pressurizing|
|2||Fuel feeding system trip/stop on trip/stop of SA fans||To avoid jamming of fuel feeding system due to no spreading air|
|3||FD fans trip/stop on high furnace pressure (>25 MMWC)||1-To avoid furnace leakage|
|2-To avoid furnace explosion|
|3-To avoid buck stay damage|
|4||ID fans trip/stop on low furnace pressure (-25 MMWC)||1-To avoid carryover of fuel at secondary combustion zone|
|2-To avoid back end flue gas ducts explosion due to accumulation of unburnt (Unburnt results into formation of CO gas)|
|5||FD fan trips on low drum level (On tripping ID fans, boiler all systems like FD,SA & fuel feeding system trip)||To avoid boiler pressure parts over heating & failure|
|1||Turbine trips on high main steam pressure||To protect turbine internals & casing from high pressure damage|
|2||Turbine trips on low main steam pressure||To protect turbine internals from saturated steam (water particles in steam)|
|3||Turbine trips on high main steam temperature||To protect Turbine internals from creep failure (Turbine internals fail on prolonged exposure to temperature more than recommended)|
|4||Turbine trips on low temperature||1-To protect Turbine from uneven expansion|
|2-To protect Turbine internals from water particles in steam (Low pressure & temperature steam will have water particles in it)|
|5||Turbine trips on high bearing temperature (>110 deg C)||To protect turbine bearing failure & other secondary system/operation interruption for long time|
|6||Turbine trips on high vibration (>5 mm/sec or >110 microns)||To protect turbine bearing failure & other secondary system/operation interruption for long time|
|7||Turbine trips on high axial displacement||To protect turbine internals from rubbing & damages|
|8||Turbine trips on high differential expansion||To protect turbine internals uniform thermal expansion & from rubbing & damages|
|9||Turbine trips on low control oil pressure||To ensure reliable operation of HP & LP actuators|
|10||Turbine trips on low lube oil pressure||To avoid damages to the bearings|
|11||Turbine trips on low trip oil pressure|
|12||Turbine trips on low vacuum or high exhaust pressure||To avoid damages to the rotor blades|
|Note: High back pressure on rotor creates reaction force to rotation of turbine rotor|
|13||Turbine trips on high back pressure|
|14||Vacuum breaker valve opens on activation of trip interlocks like||To reduce the speed of rotor within minimum time to avoid damages to the bearings & internal parts.|
|1.High bearing temperature||Note: High back pressure on rotor creates reaction force to rotation of turbine rotor|
|2-High bearing vibration|
|3-High axial displacement|
|4-High differential expansion|
|5-Low lube oil pressure|
|15||High hot well level||To avoid entry of water into Turbine|
|1||Belt conveyor trips on operation of Zero speed switch (ZSS)||1-To avoid the further damage to the belt conveyor|
|2-To avoid system disturbance & major damages to the conveyor structure|
|Note: ZSS operates when belt gets cut or slips on pulley|
|2||Belt conveyor trips on operation of belt sway switch (BSS)||1-To avoid swaying of belt|
|2-To avoid belt side edges damage|
|3-To avoid fuel spillage|
|3||Belt Pull cord Switch (PCS)||To stop the belt conveyor during emergency situations to avoid damages to the man & system|
|D||Boiler feed pumps|
|1||Pump trips on high bearing temperature||To avoid bearing damage & secondary system damage/disturbance|
|2||Pump trips on high bearing vibrations||To avoid bearing damage & secondary system damage/disturbance|
|3||Pump trips on low suction pressure||To avoid pump cavitation|
|4||Pump trips on high differential pressure||To avoid pump cavitation|
|5||Pump trips on high balance leak off pressure||To avoid further damages to the balance & counter balance discs|
|6||Pump trips on lower cooling water temperature||To avoid failure of pump’s bearings & seal|
|7||Pumps trips on over load||To avoid damages to the pump internals|
|8||BFP trips on Deaerator level low|
|1||Fan trips on high bearing temperature||To avoid bearing damage & secondary system damage/disturbance|
|2||Fan trips on high bearing vibrations||To avoid bearing damage & secondary system damage/disturbance|
|1||Motor trips on higher bearing temperature||To avoid bearing damage & secondary system damage/disturbance|
|2||Motor trips on higher winding temperature||To protect winding|
|3||Motor trips on over load||To protect winding|
|1||Over current protection||Protects the generator from over load, short circuit & earth faults|
|2||Earth Fault Protection||To protect the generator from earth faults & short circuits|
|3||Generator Differential Protection||To protect the generator from winding faults or unbalance currents in winding|
|4||Reverse Power Protection||To avoid motoring of generator during reverse flow of power to generator from other source|
|5||Low Forward Power Protection||To protect the generator running under load|
|6||High bearing temperature||To avoid bearing damage & secondary system damage/disturbance|
|7||High bearing vibrations||To avoid bearing damage & secondary system damage/disturbance|
|8||Higher winding temperature||To protect winding|
|9||Higher core temperature||To protect core|
|10||High air temperature||To limit winding temperature|
|11||High & Low voltage protections|
|12||High & low frequency protection|
|13||Rotor earth fault protection|
|14||Loss of excitation|
Read Classes of STG Trips: Class A trip This involves serious electrical faults and is considered to be the most dangerous in terms of the shock on the unit. Since it involves serious electrical faults, connections from both generator and the EHV bus is immediately switched off to limit the damage at the fault point and also to isolate the healthy system.
- Hence the whole unit need to be tripped.
- Class B trip Class B primarily relates to mechanical problems.
- This results in tripping of turbine followed by generator.
- Class C Class C involves basically external system related problems like frequency, overvoltage etc.
- This does not involve instant tripping of the unit.
CPP unit operates on house load Classes of Generator protections
|SL NO.||CLASS A||CLASS B||CLASS C|
|1||Generator Differential Protection||Loss of Excitation||Under Frequency|
|2||100% Stator Earth Fault Protection||Rotor Earth Fault||Over Frequency|
|3||Generator Over Voltage Protection||Over excitation||Pole Slipping Protection|
|4||95% Stator Earth Fault Protection||Tripping of unit transformer|
|5||Starting Over Current Protection|
|6||Over fluxing Protection of Generator|
|7||Differential Protection of GT|
|8||Buchholz Relay of GT|
|9||Trip from oil & winding temperature of generator transformer|
|These protection when operated initiate tripping of Generator Circuit Breaker, Field Circuit Breaker, Generator Transformer Circuit Breakers & Unit Transformer LV Circuit Breakers and turbine.||This results in tripping of turbine followed by generator.||Class C involves basically external system related problems like frequency, over voltage etc. This does not involve instant tripping of the unit.|
Protections & Interlocks in power plants
When should you interlock?
How Often to Interlock – How often to interlock your locs depends on how active you are and how fast your hair grows. But every six weeks to 3 months is a good guide. Here are a few things you can do to keep your locs neat and extend the time between interlockings:
If you can, limit activities that cause you to sweat in your scalp. When you go to bed, wrap your locs in a satin scarf or bonnet to keep it smooth and avoid friction while you sleep. Wear your locs in an up-do often. Avoid washing your locs more frequently than every two weeks. Don’t tighten your roots too much. If your scalp gets itchy, scratch it carefully.
Is interlock a lock and key?
Mechanical key interlocks – Mechanical key interlocks remove the ‘human factor’ by ensuring dangerous processes happen only in a designated sequence. They are simple mechanical locks designed as integral-fit attachments to the host equipment such as valves and pig traps – any equipment needing human intervention.
- Workers transfer specific keys from lock to lock (equipment to equipment) in a particular sequence.
- Each step in the process is only possible after the previous step has been completed and the sequence must be followed in the exact order to completion.
- An interlock is essentially a dual key device that locks the host process equipment in one or more conditions.
The standard condition is with one key trapped in the interlock and the valve is locked in status ‘1′ with the second key elsewhere. To operate the valve to status ‘2′ the second key is obtained from a control room and inserted into the interlock. The valve is then operated to status ‘2′, releasing the initial key and trapping the second one.
What is the difference between trip and interlock?
Process operator / commissioning – Published May 15, 2023 Trips, interlocks, permissives, and sequences are fundamental concepts in instrumentation control systems such as ESD (Emergency Shutdown), DCS (Distributed Control System), and PLC (Programmable Logic Controller).
- Here’s a summary of each concept: Trip: A trip is an action initiated by the control system that forces a device or devices to a predetermined state.
- Trips are often related to safety functions and are typically initiated by a Safety Instrument System (SIS) or a hardwired system.
- However, in some cases, PLCs or DCS may also initiate trips if they meet the necessary independence and safety integrity level (SIL) requirements.
Examples of trip signals include closing a valve, opening a valve, stopping a motor, etc. Once a trip is activated, the devices remain in the specified state until manually reset by an operator. Trips are usually controlled procedures and can only be reset if certain conditions are met.
- Interlock: An interlock is similar to a trip but is considered a “self-resetting” trip.
- Interlocks are typically used for on/off control and are not usually classified as safety-related.
- They are often initiated by DCS or PLC systems.
- However, if an interlock has safety implications and meets the required SIL rating, it may be implemented in an SIS or hardwired system.
Like trips, interlocks force devices to predetermined states (e.g., closing a valve, stopping a motor) but automatically remove the interlock when the initiating cause returns to a healthy condition. Interlocks can usually be overridden for operational reasons or defeated for maintenance purposes.
- Permissive: A permissive is a specific type of interlock used to prevent actions from taking place until certain criteria are met.
- Permissives are typically initiated by DCS or PLC systems, but if they have safety implications and meet the required SIL rating, they may be implemented in an SIS or hardwired system.
Permissives ensure that predefined conditions are satisfied before allowing an action to occur. For example, a permissive may prevent a pump from starting until the suction valve is open. Once the permissive conditions are met and the action is executed, the permissive becomes inactive.
- Permissives can usually be overridden for operational reasons or defeated for maintenance purposes.
- Sequence: A sequence refers to a prearranged set of actions carried out by the control system.
- Sequences can be initiated by events or operator actions.
- They can be either “single pass” or “cyclic.” A single-pass sequence involves a series of actions performed once, based on a specific trigger or operator command.
For example, an agitated vessel reaching a predetermined level may trigger a sequence that stops the feed pump, closes the filling valve, stops the agitator, and then opens the discharge valve after a 30-second wait. A cyclic sequence, on the other hand, involves actions that repeat based on certain conditions.
What is an example of an interlock?
In this article, we will explain what interlocks are. We will describe the different types of interlocks and give a few examples. After reading this article, you should understand what an interlock is and how to use it while programming and also designing systems.
What is the difference between switch and interlock?
Electricity Companies October 18, 2019 | 41316 views 3 min read | Written by Guest Blogger, Michele Hix, Vice President, Sales – West Region, USA. The power just went out. Is your phone ringing off the hook? This week we saw widespread weather-related power outages across the northeast United States.
PG&E issued a preemptive outage in California just days ago to reduce the risk of wildfire. No, you aren’t imagining it. Power outages due to the U.S.’s aging infrastructure, whether intentional or not, are on the rise. As a contractor, when the lights go out, you probably get calls — lots of them, asking how quickly you can prepare a home for a generator.
And that makes sense. Generators are the go-to solution for your customers looking to keep the power on. However, your electrical expertise is essential for installation, particularly when it comes to choosing how to connect the generator to an existing electrical panel.
- The two most common connection options for a generator are interlock kits and split bus panels.
- Let’s discuss the pros and cons of each.
- Interlock kits: Quick but manual Similar to a manual transfer switch, an interlock kit in conjunction with a two-pole breaker connects a generator to the electrical panel.
The kit works by ensuring the main breaker is in an off position before the dedicated two-pole generator breaker can be switched on. Thus, it isolates the energy created by the generator and blocks it from back-feeding into the electrical grid when the power turns back on.
These kits are inexpensive and relatively easy way to connect a generator. You can get a standard interlock kit for around $50 from your go-to distributor or a big-box retailer. Installation averages between 15 and 30 minutes. Compared to a transfer switch, which is limited to a particular number of circuits, an interlock kit allows you to run power from a generator to any circuit within the electrical panel.
While this is good in theory, there’s a risk of overloading the generator if it’s not sized according to the load. To avoid this situation, I suggest educating your customers on sizing the right generator for their home, as well as teaching them how to switch on and off the loads manually.
- Also, consider working with them to label each circuit as either essential or non-essential.
- That way, your customer knows which circuit breakers to turn off or keep on during an outage.
- Split bus panels: One switch solution Although an interlock kit seems like a smart connection solution for the average homeowner, some people may not feel comfortable manually switching the system and each critical circuit breaker on and off.
That’s where split bus panels come into play. Compared to interlock kits, split bus panels take the guesswork out of the process. These panels are installed in place of the home’s existing electrical panel and operate like a standard breaker panel. The difference is that a split bus panel separates critical from non-critical loads.
- When the power shuts off, the homeowner doesn’t have to pick and choose which circuit breakers to switch on like they would with an interlock kit.
- Instead, they can manually transfer power to a generator with the flip of one switch, and only feed power from that generator to the circuit breakers located on the critical portion of the panel.
In terms of price, split bus panels cost slightly more than a standard breaker panel from your distributor. The higher cost is attributed to the additional two 60 amp two-pole breakers that are necessary to transfer the power from the non-critical load section to the critical load section of the panel.
Installing this new panel is more time-consuming and expensive, but it provides homeowners who live in outage-prone areas a faster experience. Preparing for an uncertain future As we continue to overburden the U.S.’ aging grid and deal with the impacts of climate change, you’ll be called on to provide your customers options for reliable energy.
Interlock kits and split bus panels are essential products for energy generation, but they are just one piece of the puzzle. Encouraging your customers to use data to understand their energy usage and respond to it in real-time is the next step. Home energy monitors such as Wiser Energy ™ are a logical solution for this.
These systems are designed to give homeowners 24/7 access and control of their home’s power by showing exactly how much energy individual electrical devices in the home draw. Plus, offering these monitors allows you to expand your business offerings and gain a competitive edge. Get connected with the products you need to keep your customer’s power on.
Author: Michele Hix, Vice President, Sales – West Region, USA. Tags: backup generators, generator, interlock kits, split bus panel, Wiser Energy
What is the best interlock?
Easy and Affordable – The LifeSafer L250 is the most accurate, reliable, and affordable device on the market. Schedule your installation today.
Why is it important that guards are designed with interlocks?
The importance of safety interlocking – Plant & Works Engineering Published: 10 September, 2015 Alex Baggott, business development associate at Fortress Interlocks, looks at the Importance of safety interlocking in the Waste and Recycling Industry. A metal recycling firm was recently fined £35,000 by the HSE after a worker’s hands were severed while cutting metal strips on an industrial baler.
Industrial balers are used to compress recyclable material into stackable, manageable pieces before they are sent for reprocessing. This type of machinery should be extensively guarded and interlocked to ensure operators can only come into contact with the machine when the power has been isolated. Following an HSE investigation the company in question was served an enforcement notice to cease the inherently unsafe process.
The HSE found that the firm was unable to produce evidence that it had carried out a proper assessment of the risks involved in the use of a baler for cutting metal strips. Although the employee had been taught how to operate the machine by ‘practical demonstration and supervision’, he had not seen or read the operating manual.
- The immediate cause of the accident was blamed on an inherently unsafe system of work, which was contrary to the manufacturer’s operating instructions and the safety instructions on the machine.
- Waste and recycling – an inherently dangerous industry Human error is always a possibility when operating dangerous machinery and it is the employer’s responsibility to guarantee the safety of its workers by installing adequate safety systems are in place.
Waste and recycling is a particularly high-risk industry. While it accounts for only about 0.5% of the employees in Britain, it accounts for 2.6% of reported injuries to employees, according to the HSE. Ensuring compliance In reality there is no reason for many of these injuries to keep occurring – the technology to safeguard workers on all machinery in waste recycling plant already exists.
- It is also mandatory for Machine manufacturers to comply with the Machinery Directive and other essential health and safety requirements.
- One way of demonstrating compliance is by applying the harmonised standards of the.
- In this case, a risk assessment by the metal recycling firm, complying with the requirements of the Provision and Use of Work Equipment Regulations 1998 (PUWER), should have identified safety procedures as being inadequate, with further safety equipment added complying with EN ISO 13849 and EN ISO 14119 standards.
Safety interlocking One of the most effective ways to ensure worker safety in the waste and recycling sector is machine guarding. However, machine guarding alone isn’t enough to ensure safe working practices, as there is nothing to prevent workers from using designated access points to gain entry into live machinery.
It is usually necessary to include safety interlocking into the process Safety interlocks prevent access to powered machinery and stop inadvertent start-ups while personnel are inside a dangerous area. They do this by forcing operators to isolate the power before anyone gains access. Maximum protection is afforded by incorporating keys into an interlocking system – this forces workers to retain a personal safety key with them while working inside the machine, so power can only be restarted once all the keys have been returned to their original positions.
In this way, operators control their own safety. There is a common misconception that safety interlocking is an unnecessary expense, so some companies implement cheaper alternatives, such as a Lock Out/Tag Out (LO/TO) procedures. While LO/TO, when properly implemented, provides a minimum level of protection, one of its weakness lies in the inevitable failure of workers to always follow instructions.
- LO/TO’s greatest weakness is therefore interlocking’s greatest asset: a well-designed safety interlocking system forces operators to follow a pre-determined, undefeatable sequence which they cannot deviate from.
- This compensates for any possible worker error while successfully safeguarding against potential hazards.
While clearly requiring more investment than LO-TO, safety interlocking offers peace of mind to employers that their workers are safe. Any additional time and cost in the design process is likely to be significantly smaller than the potential financial burden associated with the risk of future litigation.
Added to that, electromechanical safety switches can be a very cost-effective solution that can be wired directly to guard doors, allowing isolation to occur at the point of entry. In addition, these safety gate switches are installed so that they can be easily monitored and not easily defeated. Until we eliminate the ideology that safety is an unnecessary expense in the waste and recycling industry, easily avoidable industrial accidents will continue to happen.
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Jonathan Wilkins, marketing director at EU Automation, shares his three tips for machine safety. The key European rules regulating the equipment used to protect workers have been left unchanged for more than 20 years. However, a new Personal Protective Equipment (PPE) Regulation (2106/425) will introduce key changes to the way PPE is manufactured, sold and imported within the European Union. Irrespective of Brexit, the legislation offers UK manufacturers of PPE, employers and safety managers a unique opportunity to reassess occupational health and safety. Olivier Touchais, global manager for general safety at Honeywell Industrial Safety, reports. SICK has announced it has released safety-certified versions of its TTK70 and TTK50 magnetic absolute linear encoders with Hiperface interface, widening the opportunities for accurate, absolute motor feedback systems to be integrated into safe linear drives. SICK has announced it has launched the first 2D LiDAR sensors safety-certified to PL b, specifically designed to plug a gap for lower-risk applications where safety-rated integration is needed in small, low-speed automated guided vehicles and carts, service robots or collaborative robots.
: The importance of safety interlocking – Plant & Works Engineering
What are the stages of interlocks?
If you’re new to the world of dreadlocks—or locs, as they’re often called—then you need to know what you’re dealing with before deciding that they’re the hair leap you want to take next. They’re high-maintenance at first, so you should know what you’re getting into.
- That said, before embarking on your loc journey, it’s important to familiarize yourself with the five loc stages.
- The five stages of locs are: starter, budding, teen, mature, and rooted.
- While your loc journey can take between 18-24 months, some loc-wearers find the beginning and end phases to be the easiest, because the middle stages present their own set of challenges.
Conversely, others say they find the beginning stages to be the hardest. Nevertheless, if you’re serious about having locs and can handle the upkeep, you should go for it—but not without getting up to snuff on what each stage truly entails first. We reached out to loc expert Chimere Faulk for more detail.
What material is interlock?
How is Interlock Fabric Made? – Interlock fabric is also known as double knit fabric. This is another type of weft knitted fabric. But it differs from single jersey fabric in that it’s manufactured using two rows of needles. You can picture it like two layers of single jersey fabric, knitted together back to back.
Can interlocks be used for Loto?
Lockout/Tagout Program Misconceptions – Braun Intertec As an EHS Consultant, we enjoy assisting companies with implementing lockout/tagout and confined space programs. Our clients understand the importance of a strong safety culture and the safety of their employees.
- They implement safety programs and training, and seek employee buy-in, to achieve the goal of a strong safety culture.
- They consider the risks employees As an EHS Consultant, we enjoy assisting companies with implementing lockout/tagout and confined space programs.
- Our clients understand the importance of a strong safety culture and the safety of their employees.
They implement safety programs and training, and seek employee buy-in, to achieve the goal of a strong safety culture. They consider the risks employees may be exposed to and identify ways of mitigating those risks and develop their programs accordingly.
- We often perform audits and gap assessments of our clients’ current company programs and often find that we are addressing many of the same issues across multiple employers.
- Some of these issues are attributed to confusion on the applicability of the standard.
- Some common misconceptions are: In many cases, you may choose to eliminate lockout/tagout associated risks to your own employees by having contractors perform the work.
While this is a good practice that can be used to reduce risk to your employees, a common misconception is that, by having contractors perform the work, the risk is eliminated and a lockout tagout program and procedures are unnecessary. While it is true that having contractors perform these services reduces the risk to your employees, it does not eliminate the hazards and your company’s liability.
Therefore, it is essential to have a lockout/tagout program in place in order to protect employees and contractors who may work on, around, or near the equipment under lockout/tagout. Employees who use the equipment under lockout/tagout must be trained to an awareness level because these employees are affected employees.
The Occupational Safety and Health Administration (OSHA) defines an affected employee as an employee whose job requires him or her to operate or use a machine or equipment on which servicing or maintenance is being performed that is under lockout or tagout, or whose job requires him or her to work in an area in which such servicing or maintenance is being performed.
- Even though a contractor performs the maintenance on the equipment you may still have affected employees who operate or use the equipment.
- OSHA requires affected employees to be trained on the purpose and use of energy control procedures.
- Additionally, OSHA requires employees who work in an area where lockout/tagout is utilized to be trained in the use of the procedure and about preventing them from attempting to remove a tag and/or lock and trying to re-energize the equipment.
As you can see, the training element of a lockout tagout program is necessary. Additionally, 29 Code of Federal Regulation (CFR) §1910.147(c)(1) requires that employers establish an energy control program consisting of energy control procedures, training and periodic inspections before employees perform servicing or maintenance on machines or equipment where the unexpected startup or release of energy of that equipment could cause injury.
- Contractor’s may be performing the maintenance; however, the host employees may be covered under the standard when they perform service of that equipment.29 CFR §1910.147(f)(2)(i) requires that contractors and the host employer inform each other of their respective lockout tagout procedures.
- Clearing jams in machines is defined as part of servicing and/or maintenance under OSHA’s lockout/tagout standard.
If employees may be exposed to the unexpected energization or startup of the equipment or release of hazardous energy, there is the potential for undesired hazards. The use of an Emergency Stop (E-Stop) is not an effective protection for energy control.
- This is due to several reasons; the E-stop only stops the equipment from one location and the equipment could be restarted inadvertently by another employee while an employee is clearing the jam.
- The E-stop is only a control and does not disconnect power to the machine or isolate the energy source.
- It may be possible to use E-stops in combination with other control measures such as delayed startup, alarms, and interlocked guards if those safety devices provide an alternative effective control for minor servicing, such as clearing a jam.
While machine interlocks provide an excellent control measure preventing employees from inadvertent injuries associated with removing or opening guards, they are not an alternative measure for lockout/tagout. Interlocks use control logic to stop the machine, but electrical power is still being supplied.
- Again, the ultimate goal is to completely de-energize the equipment and isolate any hazards before work is completed on the machine.
- While maintaining a strong safety culture remains a priority with our clients, many misconceptions are held about program requirements.
- While those misconceptions may be common, it’s safety experts, like those at Braun Intertec, that address these misconceptions, assess gaps in compliance, and ensure these programs are implemented correctly – and with comprehensive training – to avoid risk or injury.
If you have any questions or want assistance with lockout/tagout programs, please click the link below to fill out our Contact Us form. : Lockout/Tagout Program Misconceptions – Braun Intertec
What is the interlock device called?
A Draeger ignition interlock device (red arrow) in a Scania bus An ignition interlock device or breath alcohol ignition interlock device ( IID or BAIID ) is a breathalyzer for an individual’s vehicle. It requires the driver to blow into a mouthpiece on the device before starting or continuing to operate the vehicle.
- If the resultant breath-alcohol concentration analyzed result is greater than the programmed blood alcohol concentration (which varies between countries ), the device prevents the engine from being started.
- The interlock device is located inside the vehicle, near the driver’s seat, and is directly connected to the engine’s ignition system.
It is a form of electronic monitoring, An ignition interlock interrupts the signal from the ignition to the starter until a valid breath sample is provided that meets maximal alcohol guidelines in that jurisdiction. At that point, the vehicle can be started as normal.
A breath sample is not required to start the vehicle if the engine has been running within a time-out period, to allow quick re-starts in case the vehicle stalls, At random times after the engine has been started, the IID will require another breath sample, referred to as a rolling retest. The purpose of the rolling retest is to prevent someone other than the driver from providing a breath sample.
If the breath sample isn’t provided, or the sample exceeds the ignition interlock’s preset blood alcohol level, the device will log the event, warn the driver, and then start up an alarm in accordance to state regulations (e.g., lights flashing, horn honking) until the ignition is turned off, or a clean breath sample has been provided.
What are the different types of boiler interlocks?
There are two kinds of interlocks that are used in the boiler safety control system: 1. pre-ignition or start-up interlocks and 2. running interlocks.
What are interlocks in engineering?
Interlock A protective response which is initiated by an out-of-limit process condition. Instrument which will not allow one part of a process to function unless another part is functioning. A device such as a switch that prevents a piece of equipment from operating when a hazard exists.
What are interlocks in business?
Key Takeaways –
Interlocking directorates refers to when a member of a company’s board of directors also serves on another company’s board or within the company’s management.Under antitrust legislation, interlocking directorates are not illegal as long as the corporations involved do not compete with each other.Interlocking directorates were outlawed in specific instances wherein they gave a few board members outsized control over an industry.Interlocking directorates does not prevent a board director from serving on a client’s board.