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    Blog - Simon Says
     
Simon

Contents

UK manufactured controllers less expensive than those from the Far East (added: 27/04/2013)
How custom are our customised electronic controllers? (added: 12/04/2013)
Stop the machine, it's getting too hot! (added: 23/02/2013)
Are touch-screens any good? (added: 23/01/2013)
My temperature controller is discombobulated! (added: 1/10/2012)
Saving time and money by simplifying machine wiring (added: 24/9/2012)
Testing times (added: 9/2/2012)
To PLC, or not to PLC, that is the question.(added: 16/1/2012)
Saving Energy with Temperature Control (added: 3/1/2012)

UK manufactured controllers less expensive than those from the Far East
added: 27th April 2013

We have just started manufacturing a temperature controller for a client who has a requirement for 50 units per month. Until now, they have been using a low cost, off-the-shelf temperature controller, mass-produced in the Far East. Our client was astounded to find our solution saved nearly 10 per unit.

So what is the secret? We can assure you that Cambridgeshire labour rates are certainly not lower than those in the Far East. We can also say with confidence that our UK manufactured bare PCBs are considerably more expensive. Our overheads are higher and the economies of scale are such that manufacturing a batch of several thousands units will always be cheaper than producing only 50 units. The answer is fitness for purpose.

The Top Hex design does exactly what the client wants. The off-the-shelf solution has various features that may be useful to others, but are an expensive luxury to our client. Removing these components takes away some significant costs. The benefits don't end there. The Top Hex controller is finished off with an attractive overlay designed with our clients branding improving the appearance of the machine. It is even more significant to note that the Top Hex design reduces machine wiring allowing our client to produce more units in less time.

With a saving of 10 our client could just about afford to buy a pint in Huntingdon!

How custom are our customised electronic controllers?
added: 12th April 2013

We are often asked if we start with a blank sheet of paper on every new design? The answer is emphatically no. So, are all out designs basically the same? The answer is also a no. And finally, will technology that has been developed for our electronic controller be used on designs for other clients? You have probably spotted the pattern, the answer is once again no. So how do we do it?

The designs we produce consist of building blocks that we have developed over many years. Think of them as a bucket of Lego waiting to be built into a model. The advantage of using building blocks, is that they are proven technology to us which eliminates much of the risk of a new design. It also means we can produce a design very quickly

But what if we don't have exactly the circuit for a design? Although it would be an exaggeration to say that we have covered all possibilities, it is very rare that we come across something completely new. We can usually modify one of our standard building blocks (and don't you wish you could do this with Lego!). Meanwhile in the background, we are working on new building blocks which may or may not be useful in the future, keeping abreast with technology.

Stop the machine, it's getting too hot!
added: 23rd February 2013

Many systems with temperature control have an over-temperature cut-out. In the event of a catastrophic failure, the machine will shut down before it becomes dangerously hot. It is good practice that this over-temperature cut-out is independent of the main temperature control. Recently we have designed a number of controllers where this function is fitted to our controller - but how can this be independent?

Firstly, the cut-out circuit uses a different temperature sensor from the one used for temperature control. It does not matter with this an RTD, thermocouple, thermistor or whatever. Secondly, on the circuit board the over-temperature circuit is completely separate from the processor and uses a conventional circuit to shut-off the power. So in the unlikely event that the processor failed, the over-temperature circuit would continue to function. The over-temperature control is completely independent.

There are some significant advantages of this approach. The amount of wiring in the control panel is vastly minimised as there is no intermediate wiring between a temperature controller and the over-temperature device. Best of all, the operation of the over-temperature circuit can be cross-checked so this were to fail (and we are now talking ridiculously unlikely probabilities), we would know about it. Can you imagine pulling your reserve parachute, only to find it wasn't working? Not with a Top Hex controller!

Are touch-screens any good?
added: 23rd January 2013

We have been working with a client who is looking to replace a touch-screen human machine interface (HMI) - the sort that plugs into a PLC. He has experienced tremendous reliability problems with this touch-screen and wanted to know if touch screens are any good for industrial applications? The answer is yes, but only in the right application. He was using the touch-screen to start and stop the machine - we have replaced these with pushbuttons. Old-fashioned maybe, but rugged, hard-wearing and ideal for this application. Our controller design does have a touchscreen and this is used to configure the machine. There is nothing wrong with touch-screens, but you have to match the technology with the application.

My temperature controller is discombobulated!
added: 1st October 2012

Earlier today, we took a support call from a client for whom we have designed an electronic controller which replaced several 1/16 DIN temperature controllers and an awful lot of wiring. However, we assist our client by supporting the legacy control system even though we were not involved in the manufacture of these particular units. Our client described his temperature controller as being discombobulated - the temperature was fluctuating wildly with the heater going on and off seemingly at random.

On the new control system, we have programmed in dozens of fault conditions which bring up an alarm code on the numeric display. The alarms correspond to thermocouple open circuit, heater over temperature, heater not warming up etc. etc. Unfortunately, the temperature controllers could provide none of this information. The client was quite correct, the temperature controller was discombobulated and it was virtually impossible to deduce anything further.

After several hours of replacing components, the client discovered the thermocouple had a loose connection and was going open circuit. Had the Top Hex controller been used on this machine, we would have deduced this in less than a minute.

The conclusion - if you want to avoid being discombobulated, allow Top Hex to design a controller for you!

Saving time and money by simplifying machine wiring
added: 24th September 2012

We have recently been involved in a number of projects where we have designed a circuit board to replace wiring in a machine or control system.

For example, we have been working with a client who was producing a machine with four temperature control zones. On the fascia of their machine, they had four independent temperature controllers. There was a large amount of wiring between these temperature controllers to manage the warming up and cooling down sequence of this machine. It took an enormous amount of time to complete this wiring which was complex and therefore prone to error. Finding a wiring error often took even longer than wiring the machine!

We have designed a circuit board replacement for this wiring and are supplying pre-made cables, so the client only has to plug in 8 connectors. We have also added the isolating transformers for the temperature controllers to the circuit board along with the 24V power supply for the machine and the machine safety circuit. The result, a smaller, tidier control panel and a significant cost saving.

But to our surprise, saving cost was not the objective of this exercise! The client wanted to produce more machines with existing resources due to an increase in orders. In a challenging economic environment, we are hearing more good news.

Testing Times!
added: 9th February 2012

At Top Hex, we like to say that everything we supply is second hand. By this, we mean that every controller that goes out of the door has been functionally tested. I wanted to explain why we do this, the most common reasons that a controller will fail and what we then do to put it right before it gets to the client.

During the manufacturing process, there are various stages of inspection and test. However, the final test that is carried out at Top Hex is a functional test. During the functional test, the controller is powered up and run in a mode which is as similar as possible to the operating conditions for the product. There is a certain poetic license in this - for example we have a 9.0kW heater controller (see news story) and it is not safe or feasible to put 40A @230V through the output circuit, but we do simulate a load.

There are several reasons why a controller may have a fault. Although all circuit boards are tested before they are shipped to us, there is a tiny possibility a fault has not been picked up. Electronic components are pretty reliable, but there is still a small chance that a component is faulty, maybe from the manufacturing stage or possibly if handled badly in the supply chain. There is also the possibility that the wrong component has ended up in the wrong place or that the solder joint is poor - which can either be a human or a machine error. With a skilled workforce, this doesn't happen very often either.

So why bother? In testing a batch of 100 controllers, it would not be unusual for all 100 to pass first time. Although we are able to automate much of the testing process, it can be tedious and it is certainly time-consuming.

From our point of view, we accept that although we may be supplying a 100 controller, it may be fitted to a 100,000 machine and be shipped overseas. The implications of a controller being faulty can often be horrendous and we would rather not take this risk.

If a controller does fail the test, the solution is simply to swap the faulty part or correct the soldering and to completely re-test, in case the repair has created a further fault. The possibility of this happening is remote, in fact we can't actually remember it having happened. However, when testing, you can't be too careful!

To PLC, or not to PLC, that is the question.
added: 16th January 2012

A question that I am frequently asked is whether a Programmable Logic Controller or 'PLC' is the best solution to controlling a machine or system or if it is worth considering a custom designed electronic controller. At Top Hex, we use both solutions and in my opinion, the decision as to which is the most suitable is usually clear-cut. In this blog, I have set out some golden rules which I use and hope will point you in the right direction.

The most important consideration is whether you will be supplying the control system again in the future. If the system is a "one-off" then a PLC is undoubtedly the best solution. I would suggest that if you can imagine ordering 3-5 controllers at a time, then it's time to consider a customised electronic controller. The problem with an off-the-shelf PLC is that you will paying for features that are of no benefit to you but may be useful to somebody else. For example, most PLCs have a real-time-clock which adds several pounds of cost - great if you want to know what time it us - otherwise a waste of money!

Often the best approach is to rationalise your design wherever possible and look for similarities between systems. If you can treat each new system as a "variation on a theme" then you can potentially be running standard software and saving yourself a great deal of effort. Many of the electronic designs we produce for our clients allow enormous variations between systems. For example. we have recently designed a temperature control system which allows for between 1 and 255 channels - this should cover most eventualities!

The other advantage of a customised controller is that it is possible to make some significant cost savings by including external components on the circuit board. Power supplies, safety relays, temperature controllers and even power switching contactors can all be included in the design and will cost a lot less if they are fitted to the circuit board. Best of all, you can save time and money on wiring as there will be no cables required between these components.

If you are looking to interface with a PLC manufacturer specific communications protocol then most likely, the PLC will be your best option. If you want to include a standard interface such as an Ethernet port or a USB port then you are likely to find that the customised electronic is going to be more flexible and indeed less expensive.

Ultimately, there is very little difference in technology between a PLC and a custom electronic controller. I like to think of a customised controller as being a PLC with exactly the right combination of inputs and outputs for your system. From experience, it doesn't really matter whether the decision is made on a technical or a cost basis as the answer is usually the same! Please let me know if I can help provide you with the tools to make this.

Saving Energy with Temperature Control
added: 3rd January 2012

We have recently developed a controller which controls an electric heater in an enclosed space – e.g. an office or industrial unit. The controller takes a temperature reading from a room temperature sensor and also close to the heater. The temperature control software uses a version of our self-tuning temperature control algorithm which adapts the control parameters to achieve the optimal possible temperature control.

The system was tested in a typical environment and our client carried out comparative tests using a leading competitors BMS controller. We knew our adaptive temperature controller was good, but we didn’t realise quite how good!

The Top Hex controller consumed 20% less electricity than the leading competitor in maintaining the required room temperature. After patting myself on the back for a few moments, the engineer inside me kicked in and I am able to substantiate the dramatic efficiency savings we were able to achieve.

The competitor’s controller uses a PID based algorithm which works reasonably well at warming up the room and minimising the overshoot, to an extent at least. However, the real differences were clear when the environment changed – for example when a door was opened or when the sun shone through the window. The Top Hex temperature controller adapted its response to cope with the changes parameters. It is almost like it is carrying out a critical assessment of its response and learning from its mistakes.

 However, the competitors controller doggedly stuck to its guns using a set of parameters that suited a situation which no longer existed.   As the Top Hex temperature controller was continually optimising its response, it used less energy in the process, minimising the over and undershoots that dog conventional controllers. It is also worth pointing out that unlike the competitor’s product, the Top Hex designed controller does not need to have separate winter and summer settings – it simply adapts to suit the season.

We know from experience that the Top Hex self-tuning algorithm works equally well in multi-zone heater control applications, fast and slow responding systems (particularly in cooling applications) and even in non-temperature control for say humidity or pressure. If you have an application you would like to discuss, please email me at simon@tophex.co.uk

 

You can contact us via this website, by email or on the phone (01480 456200) to discuss an application which could benefit from a Top Hex electronic controller.
Our team will always be happy to help you.

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