Seven reasons to choose safety interlocks for MV and LV switchgear systems

The risks surrounding the operation of electrical switchgear systems are defined in detail and mitigating these is an important aspect of any health and safety policy. As set out by regulatory bodies like the HSE, in publications such as Electrical Switchgear Safety (INDG373), there are a number of important factors to consider. These are well documented and include:

  • Providing the correct training;
  • Ensuring regular maintenance;
  • Ensuring staff know the rules and their responsibilities;
  • Carrying out regular risk assessments and acting on their findings.

Each switchgear system will have its own set of operational and maintenance requirements, and it is important these are taken into consideration before implementing a safety solution.

The use of trapped key technology to ensure the safe operation of electrical switchgear systems has been established since the early 1920s. There are two principal issues that interlocking provides a solution for: the correct operation of switchgear equipment – reducing the possibility of arc flash – and the provision of safe access during maintenance.

Trapped key interlocks offer seven distinct advantages when used to safeguard MV and LV switchgear systems:

  1. They prevent personnel from accessing live terminals and cabinets.
  2. They protect equipment by ensuring it can only be operated safely.
  3. They can be operated by less skilled personnel, reducing training costs.
  4. They can reduce unintended outages caused by incorrect operation.
  5. They perform in harsh environments.
  6. They deliver a solution that satisfies the higher global MV standard IEC/EN 62271-200, defined as ‘accessible and interlocked’ as opposed to ‘accessible by procedure’.
  7. They allow the integration of LV and MV switchgear systems, different manufacturers’ equipment, and subsystem elements such as breakers and transformers.

Each switchgear system will have its own set of operational and maintenance requirements, and it is important these are taken into consideration before implementing a safety solution. In general, trapped key interlocks are highly flexible and provide integrated and retrofit solutions across a wide range of manufacturers’ equipment.

By: David Hughes, Sales Director, Castell Safety International Ltd.

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Plant maintenance and safety interlocks – myths and facts

In a recent article entitled “Unsafe Maintenance”, Judith Hackitt, chair of the UK’s Health and Safety Executive, examined some of the reasons why so many serious accidents and even fatalities continue to occur within processes related to the maintenance of machinery and equipment.

Trapped key interlocks ensure that machinery is maintained in a safe and efficient manner

Judith identified several common attitudes, concerns or faults which can ultimately lead to the safety of maintenance workers being compromised:

  • Time pressure – while machinery is stopped, money is being lost.
  • A focus on addressing everyday risks such as slips and trips, rather than mitigating the potential risks involved in machine maintenance.
  • A failure to plan maintenance activities or consider the best and safest ways to carry them out.
  • A perception that safety equipment will slow down production.
  • An absence of basic safety equipment, such as lockout / tagout and “Castell key arrangements”, which prevent access to running machinery and accidental start-up during maintenance activities.
  • A lack of the necessary ability to safely maintain equipment.

 

Trapped key interlocks can address all of these issues. It would be helpful to challenge some of the common industry misconceptions and separate fact from fiction.

“Mechanical trapped key interlocks slow down production; sensor-type safety solutions are much faster and just as safe.”

MYTH – A well designed safety interlocking system will work in harmony with existing manufacturing processes.

 “A well designed trapped key interlock can ensure the highest levels of safety integrity.”

FACT – The secret to a good safety system is a comprehensive risk assessment and understanding of the maintenance requirements. Trapped key technology will enforce these procedures.

 “I have to choose between implementing a trapped key system or a lockout / tagout system.”

MYTH – Trapped key interlocks and lockout / tagout can be combined to deliver an integrated safety system that covers planned and unplanned maintenance intervention.

 “Trapped key interlocks are expensive and inflexible.”

MYTH – With a wide installed base, trapped key interlocks have a long heritage of flexibility across heavy and light manufacturing operations. They are often found in excellent working condition even after decades of use, providing years of cost-effective safety.

“Interlocks are complicated and confusing.”

MYTH – Being process-driven, trapped key interlocks are easy to use, regardless of language or technical expertise.

 

Allied to thorough risk assessments and clear method statements, trapped key interlocks ensure that machinery is maintained in a safe and efficient manner by:

  • Dramatically reducing process risks and enforcing routines.
  • Isolating a machine’s power supply before work can begin.
  • Creating a robust process in areas where noise and communication could be an issue.
  • Performing in harsh and difficult manufacturing environments.

By: David Hughes, Sales Director, Castell Safety International Ltd.

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Castell provides safety interlocks to Zambia’s largest power station

ZESCO chooses British firm as partner for Kariba North Bank extension project

Industrial safety specialist Castell has provided several K Locks and key exchanges boxes to the Kariba hydropower station North Bank extension project in Zambia.

Castell’s interlocks, installed in Zambia’s Kariba hydropower station more than 50 years ago, are still performing well today.

Photo caption: Castell’s interlocks, installed in Zambia’s Kariba hydropower station more than 50 years ago, are still performing well today.

In the early 1960s, Castell provided interlocks to the power station; more than half a century later, the interlocks are still performing well. When the station was due to add a north bank extension, project owner Zambia Electricity Supply Corporation (ZESCO) recommended Castell to the project contractor SINOHYDRO.

Castell’s interlocks force workers to follow a predetermined process when operating or maintaining machinery and equipment, to prevent human error and safeguard workers’ access to dangerous areas.

Christy Zhang, senior sales manager at Castell China, said: “It is an honour for Castell to provide safety interlocks to the Kariba North Bank extension project. The client’s trust in us stems from the long-term performance of our interlocks.”

The Kariba hydropower station is located in the middle of the Zambezi River, 125 miles from Lusaka, Zambia’s capital. The extension project has added two 180 MW generator units, taking the total capacity to 1,080 MW and making Kariba the largest power station in Zambia.

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Trapped key interlocks vs light curtains in the food industry

In all industries it is important to balance the demand for safety with the need for fast access to machinery. The latter is vital in the food industry, for several reasons:

  1. The need to easily and hygienically clean the production environment.
  2. The impact on downtime of repetitively cleaning electronic systems.
  3. The requirement to clean all guards and accessories in the immediate location of the food area.

When protecting workers from the dangers of food processing equipment, both light curtains and trapped key interlocks can provide ways to control risk.

Light curtains offer such benefits as:

  1. Immediate access to production areas.
  2. A reduced need for guarding, which in turn reduces the time needed to clean a production area.
  3. Levels of protection ranging from full-body to finger, depending on the light curtain selected.
  4. When programmed appropriately, allowing raw materials to be passed into the production environment without halting processes.

The advantages of trapped key interlocks include:

  1. The ability to isolate the dangerous area until food machinery is made safe through timed or motion-sensing control.
  2. Higher life expectancy thanks to their mechanical (as opposed to electrical) design.
  3. Putting the operator in the hazardous area in full control of restarting the machine through the use of full-bodied interlocks and personnel keys.
  4. Resisting wash-down environments for extended periods due to their mechanical design.

 

Although light curtains can detect personnel crossing into a full-body zone, they are unable to determine if anybody remains in the danger zone when the machine restarts

The clear difference between light curtains and trapped key interlocks is most obvious in relation to full-body access. Although light curtains can detect personnel crossing into a full-body zone, they are unable to determine if anybody remains in the danger zone when the machine restarts. This can lead to a dangerous situation if workers are hidden from sight behind equipment.

Trapped key interlocks are able to protect workers while they are in the danger zone through the use of a personnel key. When the operator is in the danger zone, the key is retained with them. This means that the machine cannot be restarted until the personnel key is returned to its original position. If multiple personnel are required to enter the danger zone, several keys can be provided to allow access – the machinery cannot be re-started until all access keys are returned to the exchange point.

In summary

Ensuring that the best solution is applied will depend on:

  • Understanding the hygiene regime requirements for each application.
  • Assessing who needs access to these areas, why and how often.
  • Evaluating access requirements: full- or part-body?
  • Conducting a risk assessment to understand the specific risk around the machinery or equipment.
  • Remembering to assess risk both pre- and post-implementation of a solution.

By: David Hughes, Sales Director, Castell Safety International Ltd.

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How figure symbol trapped key interlocks improve efficiency in the food industry

After safety, the most important area of focus in the food industry is the efficiency of a production line. Ensuring that deliveries meet the demanding schedules set out by retailers is key to maintaining and growing market share for food producers in every market.

Figure symbol trapped key interlocks are designed to be faster and easier to clean, making them practical for the food industry.

It is widely understood that trapped key interlocks, by enforcing procedures, ensure that workers remain protected across a manufacturing site. From raw material receipt through the manufacturing process to the despatch of goods, trapped key interlocks ensure that potential accidents are designed out of each process. In many cases trapped key interlocks, and figure symbol interlocks in particular, can also have a very positive impact on efficiency and overall equipment effectiveness. They achieve this in a number of ways.

1)    Reducing downtime caused by hygienic processes

Being mechanical in design, trapped key interlocks do not suffer from the water-induced electrical faults that can see alternative technologies fail in just a few months.

2)    Reducing downtime during unscheduled interventions

Machine guarding refitted under the pressure of a manufacturing plan which has not allowed for an unplanned stoppage can be unreliable. This can cause issues where guards are incorrectly placed and misaligned sensors will not allow the machine to restart, extending downtime. Through key transfer, trapped key interlocks enable faster restart as it is immediately clear which guard has and hasn’t been refitted.

3)    Avoiding damaged sensors

In a fast-paced manufacturing environment, damaged safety sensors can introduce delays and the potential for hazardous operation. Trapped key interlocks’ robust design enables them to operate safely for many years and they often outlast the design life of the equipment they are fitted to.

4)    Reducing the need for hygiene

Washing down machinery in the food industry after operation is an expensive and time-consuming overhead. Any opportunity to reduce this cost improves overall profitability. Figure symbol trapped key interlocks are designed to be faster and easier to clean. Typical lock mechanisms suffer from plugging where food and debris enter the lock, reducing the performance of the mechanism. Unlike a conventional key and lock mechanism, figure symbol interlocks are designed so that the coded key operates with the like-coded lock surface, rather than engaging into the typical internal tumbler mechanism. Figure symbol locks remove this unwanted feature, making them more practical for the food industry.

5)    Improving operator efficiency

Figure symbol trapped key interlocks improve operator efficiency in multi-language and temporary worker environments by introducing a coding system, which is easy to identify, and preventing shortcuts and operator error.

By: David Hughes, Sales Director, Castell Safety International Ltd.

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Food manufacturer improves warehouse safety with Salvo™

Greencore installs drive-away prevention system at four UK sites

Leading convenience foods manufacturer Greencore has installed Castell’s drive-away prevention system Salvo™ at four UK sites. The interlocking device is providing loading bay safety at Greencore’s Kiveton, Warrington, Wisbech and Park Royal facilities.

Greencore has installed Castell’s drive-away prevention system Salvo™ at four UK sites

Part of the risk assessment process identified a potential for a drive-away from the loading bays. Although Greencore had systems and procedures in place to prevent this type of occurrence, the company investigated several potential safety systems to negate the risk, before deciding that Salvo™ was the right choice.

“Castell gave us the most competitive price and their product was the best suited to the task in hand,” said Simon Chamings, safety, health and environment officer at Greencore Kiveton. “Since installing Salvo™ we’ve had absolutely no problems whatsoever.”

Dave Massey, Greencore Kiveton’s transportation shift manager and a former HGV driver, was unequivocal in his verdict: “In terms of loading bay safety, it’s the best thing I’ve ever seen.”

The shunter fits a Salvo™ Susie lock to a trailer’s exposed emergency airline, which immobilises the trailer and releases a key from the end of the Susie. The shunter then inserts the key into the SCP+ control panel unit next to the bay door. Turning the key powers up the bay, and illuminates a green beacon inside the warehouse and a red one in the yard. While the bay door is open, the key remains trapped in the SCP+ and therefore the trailer cannot be moved. When loading or unloading has been completed, the process is reversed.

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The top five ways trapped key interlocks protect workers in the food industry

Trapped key interlocks provide fast, safe and reliable access to machinery, prevent shortcuts and enforce procedures. This is achieved through the transfer of keys as the process is stopped or started. The repetitive wash-down procedures common to the food industry can affect the reliability of electrical safety devices, but the rugged, mechanical nature of trapped key systems makes them particularly suited to food processing applications. Here are the five most popular areas in which mechanical interlocks safeguard workers in the food industry.

1) Palletisers, blenders and mixers

These machines present the same risk – that personnel can be exposed to danger without being immediately visible to others – but for different reasons. In the case of palletisers, the large size of the segregated area, the equipment within it and the full pallet itself make it easy for an operator standing outside the machine guarding to miss a colleague’s presence inside. Blenders and mixers, on the other hand, present an impenetrable metal wall at ground-level to external workers.

Electronic methods of detection are sometimes unable to ascertain if individuals remain within a hazardous area. But trapped key interlocks, through the use of a personnel key, and lockout / tagout procedures can ensure that all operators and engineers are safe prior to the machine running. The operator retains the personnel key the whole time they are in the protected area, putting them in control of the machine start-up. Until this key is returned to its original position, there is no way to restart the machine.

2) Clean-in-place

The nature of the chemicals used in clean-in-place operations means that any product contamination is extremely hazardous to human health. It is therefore imperative that the correct procedure is followed and completed prior to food production starting. Trapped key interlocks force workers to follow a strict process, without them deliberately skipping or inadvertently missing steps.

3) Product filtration valves

Maintaining and replacing filters in food processing pipework while product flow is present carries two risks. First, removing filters can lead to loss of product and high clean-up costs. Second, operators can be exposed to high-pressure and / or high-temperature product. Interlocking product flow and access to filters ensures that access can only be gained when product flow has ceased i.e. when the valve is closed.

4) Dosing

Ensuring the correct dosage of ingredients or additives is administered at the right time can prevent product being spoiled or wrongly formulated, and money being lost. Companies that interlock dosing valves maintain product consistency. Ingredients and additives can only be introduced in the correct order and individual steps cannot be missed or ignored.

5) Ovens and chillers

The risk when maintaining ovens and chillers is that the temperature may not have returned to a safe enough level to allow prolonged exposure by maintenance and operation teams. Having a robust method to guarantee enough time has elapsed before access can be granted means that personnel remain safe while in the danger zone. The access key to the hazardous area is only released once sufficient time has passed to allow the temperature to return to a safe level. The provision of a personnel key that is kept by workers while they are exposed to danger inside the equipment means that they remain in control of the process.

By: David Hughes, Sales Director, Castell Safety International Ltd.

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Castell hosts 2013 channel partner forum

Event helps ensure customers worldwide get latest technical advice

As part of its global sales growth strategy, Castell Safety International recently hosted a forum for its network of international distribution, or channel, partners.

Castell hosts its 2013 Channel Partner Forum

The event saw channel partners receive training in the principles of trapped key interlocking, undertake a manufacturing facility tour and attend presentations focused on Castell’s new product development, vertical market strategy and emerging applications.

Castell’s channel partners help ensure that customers receive expert technical advice, market- and application-specific knowledge, customs brokerage and timely delivery in a large number of countries around the world. The company’s network of partners spans over 20 countries on four continents and includes qualified technical sales engineers who speak more than a dozen languages in total.

Castell sales director David Hughes added: “This event has been a great opportunity to educate our channel partners on our vertical market strategy and help them become experts in our key markets of energy, industrial, manufacturing and transport.”

Channel partners gave presentations on their own markets and Castell success stories, which encouraged discussions on new opportunities across the distribution network. Perry De Brujn, of TSA Safety Group, the exclusive distributor for Castell in the Netherlands and Belgium, commented: “The channel partner presentations greatly enhanced my awareness of the huge range of applications which can be safeguarded using Castell products.”

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Safety interlocking manufacturer appoints new distributor in West Africa

Wined Resources will distribute full Castell Safety International product range

British safety interlocking manufacturer Castell Safety International has agreed a new distribution partnership with Wined Resources, a prominent specialist distributor of safety equipment in Nigeria. The new partnership marks the first time Castell products have been made available through a distributor in West Africa.

A Nigerian company, Wined Resources is based in Warri, a hub of West Africa’s oil and gas industry, and has affiliations with multinational companies. Wined Resources will deliver a full range of distributor services including on-site sales visits, order processing, customs clearance and delivery, and after-sales support.

Castell sales director David Hughes commented: “Nigeria is a growing market for Castell and we are proud to partner with Wined Resources, an organisation with over 20 years’ experience serving the Nigerian business community, and with deep knowledge and expertise in several key industries. Their skilled technical sales team will be able to quickly help customers wanting to buy our products.”

Edwin O. Ezeocha, Wined Resources managing director, added: “Castell’s safety products are well known for their high quality and reliability, and will be an excellent complement to our existing safety product range. We see the potential for a vast range of safety applications across numerous industries in Nigeria.”

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Castell launches new spring-loaded interlock

KSP more efficient than traditional bolt interlocks

Castell has launched a new spring-loaded lock, the KSP, to increase efficiency in traditional bolt interlock applications.

Spring-loaded bolt interlock

The KSP is a spring-loaded version of the Castell K lock, and uses an internal spring to automatically extend the lock’s bolt to its fullest extent when circumstances permit. The key-operated mechanical interlock is suitable for the safe locking of simple actuating mechanisms.

The KSP is generally used at the start of a process and traps a key while equipment is running. When the equipment is switched to a safe state and the aperture in the actuating mechanism is aligned, the spring-loaded bolt automatically extends and is locked in position. This represents an advantage over existing bolt locks as the operation happens immediately and without the need for human intervention.

Once the equipment is in the safe state, the key is released and can be used to gain access or start a separate process. The key must be inserted and turned, retracting the bolt, to allow the actuating lever to be moved again.

Paul Marks, Castell’s technical director, said: “We were already using a spring-loaded lock within our product range and realised that the same device could deliver significant benefits elsewhere for our customers. We view the KSP as an important addition to our existing K bolt interlock range.”

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