A fluid amplification technique from the oil and gas industry could soon be cleaning your lounge carpet. Alan Quinn reports on the latest Hoover development.

No bags to buy…no replacement filters to buy…that’s the proposition offered by the Hoover Vortex vacuum cleaner available this month to the electrical trade.

The Hoover triple Vortex system separates dirt particles from the air using centrifugal force in a multi-stage cleaning process. It is a form of fluid amplication whereby fine dust is continually scrubbed from the transport air over and over again. Whilst the principle of a bagless cleaner is not new the Vortex goes further and includes stages where the air is finely cleaned. It is this process which prolongs the life of the filter as the final stage is a further cleaning in a high efficiency vortex. And if the air is not clean around it goes through stages two and three again.

Hoover teamed up with BHR Group engineers at Cranfield. The cyclone technology known as amplified spin-cleaning was originally developed for the oil and gas industry. A compact in-line device known as Wellsep used to separate gas from crude oil was miniaturised at BHRand this was the starting block for the development of the Hoover Triple Vortex separation system.

The new separator comprises an entirely novel multi-stage vortex arrangement with a built-in or feedback loop. Three stages cooperate as follows: a first stage vortex is induced in the dust container which spins our more than 90% of the dirt. Semi-clean air is then drawn into a second-stage involute separator which induces a high velocity vortex to concentrate fine dirt into about 20 of the air flow. This portion of the flow is then cleaned using a third stage miniature cyclone – smaller cyclones generate higher g forces and are better at removing the finest particles. Transport air from the third stage is re-injected into the second stage vortex for a final “scrub” before exiting perfectly clean.

• Hoover European Appliance Group
• Caroline Knight
• Tel: 01685 721222

• BHR Group
• Dr Matt Davies
• Tel: 01234 750422
• http://www.bhrgroup.co.u k

May 1999

We all know that ergonomics in the workplace is important. And you can leave the technicalities to the suppliers, as Bott tells David Norris

There may be companies which are concerned only with avoiding prosecution by the Health and Safety Executive, with little regard for the well-being of their workforce. But more and more British workplaces are seeing the benefits of an ergonomically efficient working environment, according to storage and workshop hardware specialist Bott. And as one of the company’s customers, Blue Circle, says: “If your workforce knows that a system has been designed around them rather than being imposed on them, they are far more willing to give their best and be loyal to the company.”

Injury potential can be minimised in several ways. Make production and finding equipment easier, minimising risk of strain or direct injury. Provide a clear, visual map of the workplace for ease of equipment and tool location and re-location (and define work and storage areas). Make sure potential hazards are more than obvious. And make certain that, by use of intelligent, expedient storage and work areas, the space around machinery is left clear and uncluttered.

Even flooring is a potential hazard: it must be carefully designed for minimum operator fatigue and maximum accident prevention.

Bott equipment can be colour-coded if required, not only enhancing the quality of the visual map in the workplace but also making sure that certain colours denote certain types of hazard. The silhouetting of toolboards can, like colour-coding, make tool and equipment location and re-location easy, highlighting any that are missing or left lying around to provide potential hazards.

Mobile, adjustable storage facilities of varying shapes and sizes enable a workshop which is safe and highly organised to be taken to the task, rather than the worker having to continually waste down-time by fetching equipment from a static source.

Look at security as well. Mechanisms such as safety triggers make certain that drawers do not suddenly open whilst static or in transit. And of course the old favourite of ergonomists, seating: ensure that where machine fitters and mechanics have to stoop or work at low heights or where operators have to stand for long periods by a machine or workbench, the design makes for maximum comfort and maximum adjustment.

• Bott

November 1999

Are you considering using robotics for the first time, but don’t know where to start? Tommy Miller suggests one possibility: Edubot

Taking the first steps towards using robotics can be a very daunting prospect for many people. The fear of the unknown, along with the possibility of spending thousands of pounds on equipment that no-one can operate, let alone understand, often discourages companies from investing in technology that could lead to long-term time and cost savings.

To address this problem, Robotica has designed a programmable robotic arm for use in the teaching of robotics technology. The Edubot is a six-axis open kinematic robotic arm that can be supplied pre-assembled or in kit form, and is controlled through a PC via Robotica’s control software. At under (UK pounds)500, Edubot allows the building, programming and operation of a robot to be learned in an entertaining, cost-effective way.

As well as performing simple pick-and-place tasks, the robotic arm can be interfaced with other devices to complete a sophisticated robotic system. Analogue and digital inputs allow limit switches, pressure sensors, infrared sensors and ultrasonic distance sensors to be connected, and digital outputs enable relays, motors, conveyors, solenoids and LEDs to be controlled from the computer. The software and electronics are suitable for radio-modem communication, so Edubot may be used in wireless mobile robotics applications.

Servo controller

At the heart of Edubot is the Robotica R/C servo controller II, with two analogue inputs, four digital inputs and three digital outputs, connected via an RS232 connector to the computer serial port. Up to four robots can be controlled from one serial port.

The control software supplied with the Edubot includes the following:

• Mouse and/or joystick control.
• R/C servomotors can be controlled either manually or through a program sequence.
• All input and output states can be observed constantly, and they can also be controlled through a mouse click on the screen.
• Different configuration settings can be created for immediate recall, such as servo limits, park position, labels and operational mode.

Programming the unit to perform various tasks is simple thanks to easy-to-use, efficient single character commands, and a comprehensive ‘Help’ menu that is incorporated within the software.

• Robotica

February 2000

The Government’s Environmental Technology Best Practice Programme says that tagging saves money. Tommy Miller reports on how it can

Essentially, the tagging of products can reduce waste for companies through automation, distribution, production/product quality, recycling/ disposal, security and warehousing. It is hardly surprising, therefore, that tagging is now becoming more generally accepted as an integral part of the manufacturing process

The type of tagging that is used will depend on many things, but there are three main categories of tag to choose from. Whilst optical tags (such as barcodes and two-dimensional codes) are low cost, they are limited in the amount of data that they can hold. Magnetic and electromagnetic devices are slightly more expensive, but they are read-write devices and do not need a clear line of sight. Another disadvantage of this category of device is that they are not especially robust: they are vulnerable to temperature and magnetic fields and they need to be kept away from metal objects.

If the budget will allow it, radio frequency identification is often the best option. These devices can store large amounts of data, they are read-write, reasonably robust and multiple tags can be read simultaneously.

Once a tagging system is operational, it becomes far easier to identify individual items or packages containing many items. Tagging can also be used to identify the location of objects, and relevant information about those objects can also be retrieved or stored. Information about objects is particularly valuable. This might relate to the process conditions prevalent when the object was manufactured, or a batch reference can be used as they key to a vast database of information.

Cost savings can accrue from staff no longer having to enter data manually, or from not having to search for products. Higher quality data can cut the amount of rework and can save production time. Furthermore, the availability of up-to-date, accurate data can reduce the need to hold stocks of parts, sub-assemblies or finished goods. Another important point is that tagging can also leads to benefits for the environment.

• The Environmental Technology Best Practice Programme is a joint DTI and DETR programme.
• For more details on tagging from the Environmental Technology Best Practice Programme call the Environment and Energy Helpline on 0800 585794 (UK only)

October 1999

A new standard for electrical and fluid power installations on machines seems to be emerging. Tommy Miller investigates

Desina is described as a fully comprehensive system to bring standardisation and decentralisation to the field of fluid power and electrical installations on machinery and equipment; the word itself is an abbreviation of Decentralised and Standardised Installation technology. Backed by the VDW (the Association of German Machine Tool Manufacturers), Desina is expected to become widely accepted in the machine tool, automotive manufacturing and wider engineering markets. Already there are well known manufacturers – such as Igus, Siemens and Balluff – who have introduced Desina-compatible product ranges.

One of the main advantages of Desina is that it builds on current standards for communications and connections, rather than starting from scratch; so, for example, Profibus-DP and Canbus and Interbus-S are all supported. Furthermore, by defining standard components, interfaces and connection elements, different fieldbus systems can be made compatible on a common physical basis.

Through developing Desina, the intention is to encourage machine builders and system integrators to implement decentralised installation techniques and to use standard components. There should therefore be savings to be made in planning, installing and operating the equipment.

Standards have been proposed by Desina for components such as inductive proximity switches, hydraulic valves, I/O modules motor feeders and cabling (including plugs and sockets). It is then down to individual manufacturers to check the compatibility of their existing products or to develop new or enhanced products if necessary.

One company that has taken the Desina approach on board is Igus. This company, well-known for its ‘energy chain’ cable conduits and compatible Chainflex flexible cables, has developed a range of cables that are recognised as conforming to the Desina standard. These recently introduced products are:

• Servo cables, shielded (orange)
• Measuring system cables, shielded (green)
• Fieldbus cable (violet)
• Sensor/actuator cable, unshielded (yellow)
• Control cable, unshielded (grey)
• Power cable, unshielded (black)

The violet fieldbus cable is particularly noteworthy because, to make it compatible with the relevant fieldbus standards, it carries four copper conductors and two optical fibres.

 The Desina web site can be found athttp:// desina.arkaden.net/english/flyer_e.htm 

• D esina

November 1999

Sealed connectors have traditionally been too expensive or too bulky. But Tommy Miller finds a range that breaks the mould

When specifying sealed connectors for use in industrial or harsh external environments, equipment manufacturers have always been faced with the question of whether to choose costly circular connectors approved for hazardous areas or even more expensive military specification connectors with their inherent complexity and servicing problems.

A lower-cost option has been to use BS4343/IEC 309 type connectors, of which there are many on the market, but these cannot provide the level of sealing required for more demanding applications and are bulky and complex in construction.

The gap in the market between the two types of connector has now been filled, however, by Bulgin with the introduction of its new 900 Series Buccaneer heavy duty sealed connectors. This new range offers high performance, rugged construction and reliable environmental sealing but at a much lower cost than rival connectors of similar specification.

Being rated for high power applications of up to 32A per pole at 600V AC/DC, the robust connectors are available in 2, 3, 4 and 5-pole variants. The 3, 4 and 5-pole versions incorporate leading earth contacts, making them suitable for single or three-phase applications. All offer specifications and approvals to match even the highest priced connectors in their field.

Typical applications for the 900 series Buccaneer include industrial pumps, motors and fans, gas and petrochemical plants, and marine and underground environments. With the high-end specification at a low price, coupled with ease of assembly and servicing, Bulgin is confident that entirely new applications will be created by this type of environmentally sealed heavy duty connector where safety and connection integrity is vital.

The 900 series Buccaneer range includes a number of body styles: flex cable, in-line flex cable, chassis mounting, flange mounting and bulkhead mounting. Moulded in a new UL94V-O rated polyamide material, the connectors are strong and impact-resistant, as well as possessing flame retardant properties.

Environmental sealing to IP68 is achieved by simply tightening a locking ring on the connector body, with no supplementary sealing being required. Screw fixing terminal contacts, designed to accommodate conductors up to 4mm?, make termination and maintenance in the field a simple matter due to no special tools or skills being required.

Positive locating keyways eliminate mis-connection, and two connectors with the same number of poles are able to be safely used on the same piece of equipment by utilising alternative keyway polarisations.

• Bulgin

November 1999

Interlocks can be incorporated into rotary switches control units exchange boxes and door locking devices to govern many types of industrial equipment. Here’s how to specify them correctly.

Safe operation of plant and machinery can only be ensured by following a correct procedure. Actions carried out incorrectly or in ignorance of the potential dangers can lead to injury or death or damage to plant and equipment. Instructions or safe working practices alone do not guarantee correct operation.

Fitting interlocking imposes effective physical controls which lead an operator through a safe and predetermined sequence of events. By eliminating the potential for human error interlocking ensures that the correct action is performed in the correct way every time the equipment is used.. Interlocks can be applied to most items of machinery and plant that must be operated in a pre-determined or controlled manner. Other common applications include robot production lines HV and LV switchgear food slicing plant transfer machines presses paint plants moulding machines dryers shot blasting machines shredders saw mills palletisers and guillotines.

For example interlocking a machine tool will ensure that it is switched off and has come to rest before access to moving parts is permitted. Similarly interlocks fitted to electrical switchgear will ensure that the power supply is isolated before allowing entry to a high voltage area. Not only does key transfer interlocking impose safe conditions of access to dangerous machinery it also ensures that equipment cannot be restarted until all personnel are clear of the hazard and the key sequence has been reversed.

Key interlocks use a special type of lock mechanism which traps or frees an operating key when associated machinery or plant is in a certain condition. Typically one key is supplied to operate each pair of interlocks. The transfer of keys from one interlock to another ensures that equipment can only be operated in a safe predetermined sequence.

Interlocks can be incorporated into rotary switches control units exchange boxes and door locking devices to govern many types of industrial equipment. Fortress Interlocks uses a high security radial pin tumbler mechanism that is robust secure and easily maintained. The design allows over 100 000 non-masterable lock combinations plus an additional series of masterable locks for special applications. Each different key combination is allocated a code number of up to 10 characters by which the lock and key are identified.

Fortress Interlocks has published a new brochure to guide safety engineers through the step-by-step specification of customised access equipment using simple table diagrams.

• Fortress Interlocks

September 1998

A radically different approach to cabinet design by Willsher & Quick should bring accessibility and utilisation benefits for installers and end users

The new Access system free-standing enclosure from Willsher & Quick dispenses with conventional construction techniques by incorporating square tubular top and bottom frame sections, linked by a pair of heavy-duty vertical extrusions centrally positioned either side. This creates a sturdy framework onto which a mix of quick-release exterior panels and doors are attached. This construction technique completely eliminates the need for the traditional four-corner uprights found in other conventional types of floor-standing enclosures.

Also, the exterior cladding can be removed from the corner areas, without affecting the structural integrity or security of the cabinet, whilst the absence of structural corner posts permits easy cable bundling and routing in and around the 19in vertical mounts, down the sides or between bayed cabinets.

All exterior panels, including the top and doors can be fitted by a single person releasing a spring-loaded catch. This not only makes transportation and final positioning easier, it also allows uninhibited but secure access to internal equipment from the front, rear, sides, top and base.

To simplify cable and equipment installation, the front and rear 19in mountings of the 800mm wide models are fully adjustable internally, fore, aft and laterally. Other configuration and equipment mounting options allow for a convenient mix of both active and passive components. An optional swing-frame assembly which can be retrofitted, offers further benefits.

The design and shape of the top and bottom frames, forming the perimeter support of the cabinet, offers impressive top and bottom cable access. When Access Racks need to be installed next to walls, the narrow section frame and large, open-top area capability enables substantial wall-mounted cable runs to enter freely into the top of the cabinet, without undue bending of cables.

The Access Racks are available in 600 and 800mm widths, 675 and 875mm deep and in four popular heights: 27U, 39U, 42U and 47U. They are particularly suited to structured voice and data cabling, communications server and A/V broadcasting industries, as well as traditional electrical and electronics applications.

All Access cabinet front doors have fully vented vertical frame members to assist natural internal convection. Where extreme heat dissipation is of concern, a forced air cooling system can be introduced and customised. Other accessories include plinths and shelves, cable management units, power distribution units, fan trays and mountings.

• Willsher & Quick
• Tel: 01278 783371

June 1999

Devicenet is becoming more popular and is being used on smaller plant and machines, as our man John McGreal finds out

It is hard to believe that Devicenet was only launched in 1995. Since then, this open fieldbus system has matured, largely as a result of the wide range of products that are now available for connecting to it. Indeed, the second generation of Devicenet components is proving to be physically smaller and priced lower – now comparable with conventional devices – which counteracts two of the traditional arguments against device-level fieldbuses. But one of the trends to have emerged more recently is that more users are turning to Devicenet for smaller assembly cells and individual machines. So why is this?

Looking more closely, it is apparent that many users are finding Devicenet is particularly useful for using inside control cabinets – and this tends to lead to it being used beyond the control cabinet as well. But inside a control cabinet, Devicenet saves space, makes the connection of components such as drives and soft starters far quicker and, perhaps more importantly, gives access to data that simply was not tapped into previously. This issue is usually of more importance to the end user than to the panel builder or machine designer, because access to data means that diagnostics are easier and maintenance can be carried out more efficiently.

Another reason why Devicenet is increasingly being used at a machine-level is that production lines are often assembled from several machines, some of which might come from specialist suppliers. If a fieldbus is used, it is simpler to build and test the individual machines, as well as to assemble and test the complete production line.

A new Devicenet development announced by Rockwell Automation is the Armorblock Maxum connection block. This builds on the success of the Kwiklink (which allows rapid connection to a profiled four-wire connector) by adding smart I/O diagnostics. Rockwell says: “Armorblock Maxum makes full use of Devicenet’s advanced communications capabilities such as short-circuit, open-wire and no-load detection, auto-baud selection, selectable I/P filter times and self-configuring PNP/NPN inputs. Armorblock Maxum opens up a whole new world of I/O diagnostics.”

Any other questions?

Covering a broader range of topics than just Devicenet, there is a seriously useful booklet available from Rockwell Automation entitled Industrial Communications Networks. This is written in a reader-friendly question-and-answer format and should help you to decide whether a fieldbus (of any variety) is right for your needs and, if so, what types you should be considering. It’s the sort of guide that your colleagues will want to borrow!

• Rockwell Automation

September 1999

Pilz has updated its well-known PC-based guide to its range of safety products. Tommy Miller tries out the latest version

Having decided that your machine needs to be CE marked, and that it must therefore have the appropriate safety components, how do you choose what to use? Of course the manufacturers all have plenty of literature, some of which is easier to read than others, but it can still be a laborious process. Pilz is trying to lead the way with an extremely well prepared interactive guide to safety products, prepared as a CD-Rom. The latest version, 4.03, is now available free of charge.

But as well as helping you to make the all-important selection, the CD-Rom also contains all of the technical information that you will need in order to check the specification (it is still your responsibility, remember) and to ensure that the components are correctly installed on your machine. When a selection has been made, it is simple to click on the ‘print’ icon to output a hard copy for your records. This shows the path taken in the selection process, but it is also possible to print the full technical data and wiring information for the hard-wired safety relays (this data is provided as PDF files, readable with Acrobat Reader).

For users who are new to subject there are some clear explanations provided. Take, for example, ’severity of injury’. The help screen first gives a straightforward definition of a slight injury and a severe injury and then augments this with: “Take account of the worst case injury. If this is no more than a slight cut or bruise, then select S1 [slight]. If the consequences are more severe, up to and including death, then select S2 [severe].”

Making a product selection couldn’t really be made any simpler. First you select the product type from a pull-down menu, then you use the mouse to select the severity of injury, frequency of exposure and possibility of avoidance. As each of these selected, the screen changes to show potential safety category (B, 1, 2, 3 or 4). The list of candidate products is also revised each time a selection is made. But the clever bit is the way in which the table of safety categories is cross-referenced on screen to the list of candidate products, highlighting those which are more (or less) suitable.

Safety products that are covered by the CD-Rom include everything from the established base-level PNOZ safety relays to the PSS programmable safety systems. Other products listed are: two-hand relays, safety gate monitors, contact blocks, speed monitors, standstill monitors, safety time relays and the PNOZ plus modular safety system.

Once you have made your product selection, Pilz has also provided a facility on the CD-Rom for finding your local distributor or, indeed, one near to your customer, whether in the UK or abroad.

• Pilz 

October 1999