Author: Jamie Groves

What is a thermistor?

Posted on by Jamie Groves

A thermistor is an element that senses temperature and is made up of sintered semiconductor material which displays a big change in resistance in proportion to a small alteration in temperature. They normally have negative temperature coefficients meaning the resistance goes down as the temperature goes up.

Thermistors are constructed using a combination of metals and metal oxide materials. Once they are mixed, the materials are formed and pushed into the required shape. They can then be used naturally as disk-style thermistors without any changes needed. Alternatively, they can be further shaped and put together with lead wires and coatings to create bead-style elements.

How do thermistors compare to RTDs?

Whilst RTDs change resistance in an almost linear way, thermistors have a very non-linear change in resistance and reduce their resistance as temperature increases. They continue to be a popular way of measuring temperature for several reasons including:

  • Their increased resistance change per degree of temperature offers better resolution
  • There is a high level of repeatability and stability
  • Impressive interchangeability
  • Their small size means they can respond faster to changes in temperature

Thermistors typically have two types of coatings: epoxy for use in lower temperatures (-50 to 150C) and glass coatings for higher temperature applications (-50 to 300C). These coatings are used mechanically to protect the bead and wire connections whilst offering a degree of protection from corrosion and/or corrosion too. A very small diameter and solid copper or copper alloy wires are normally supplied with thermistors. In most cases, these wires are tinned to allow for easy soldering.

Base resistance

NTC thermistors decrease in resistance with increased temperatures. This is also the case for how much resistance change per degree it will provide. For quite low temperature applications (-55 to around 70C) lower resistance thermistors are generally used. Higher resistance thermistors are used for higher temperature applications in order to optimise the resistance change per degree at the temperature that is needed. These elements are available in a range of resistances and “curves” and resistances are typically specified at 25C.

How does a thermistor work?

Unlike RTDs and thermocouples, thermistors don’t have standards linked with their resistance versus temperature characteristics or curves. As a result, there are several different ones you can choose from. Each material will offer a different resistance vs temperature “curve”. Certain materials will have better stability whilst others have higher resistances so they can be made into bigger or smaller thermistors.

What thermistor is right for your application?

Whether you are replacing a thermistor or getting one for a completely new application, there are three key things you will need to consider in order to achieve the best result. These are:

  • For new applications, select proper base resistance or correctly specify the base resistance of the one that you are replacing.
  • When specifying resistance-temperature correlation, make sure to be precise. For replacements, have info on existing thermistor ready
  • Packaging style and size

Thermistor accuracy

Thermistors are one of the most precise temperature sensors on the market. However, they can be quite restricted in terms of their temperature range, operating across a range of 0 to 100C. If you don’t think a thermistor will be right for your normal thermocouple applications, stick with your thermocouple. Despite having a number of useful benefits, such as being chemically stable and so not massively susceptible to aging, a thermistor isn’t the right fit for every industry or process because of the limited parameters.

Size or sensor package style

When the user has determined the right resistance and curve, they should consider how they intend to use the thermistor. So, when they are choosing the right size or packaging for the sensor, it’s important to remember that in the same way as any other sensor, a thermistor will only measure its own temperature.

Thermistors cannot be submerged in a process. They are small and quickly react to temperature changes since they are only separated from the environment by a thin epoxy layer. However, you can get different styles of thermistors for different uses.

General purpose

General purpose designs can be work in a broad range of applications. From electronic equipment to structures, processes and design, and reliability testing uses, sensors of this style are easy to fit and monitor over time.

Liquid immersion measurement

Thermistors need to be protected from corrosion when they are exposed to liquids as well be carefully positioned in the fluid so it will arrive at the required temperature. This is normally done using closed ended tubes and housing that are specifically designed for the job. You need to take care and ensure that there is a clear thermal path to the thermistor and that thermal mass is as small as it can be.

How can TRM help?

At TRM, our team provide engineered solutions that perform at the highest temperatures and in the harshest environments. We are specialists in all thing’s temperature measurement, trace heating, and fireproof wiring, offering a range of useful products like MI thermocouple cable to ensure our customers get the solutions they need in their business operations. Contact us today to discuss your specific requirements and what we can do for you.

 

What is a resistance thermometer?

Posted on by Jamie Groves

A resistance thermometer or resistance temperature detector (RTD) is a device which measures temperature through the resistance of a conductor. Resistance of the conductor can vary with time. It is this property of the conductor that is used for industrial temperature measurement. The RTD’s primary purpose is to produce a resistance alteration in response to temperature.

Metals usually exhibit high temperature coefficients, indicating resistance increases as temperature rises. On the other hand, carbon and germanium typically demonstrate low temperature coefficients, thereby showing a resistance decrease with increasing temperature.

The material used in a resistance thermometer

The resistance thermometer has a sensitive element that is made from the purest metals such as platinum, copper, or nickel. There is a direct connection between the resistance of the metal and temperature. In most cases, platinum is used in resistance thermometers due to its high accuracy, stability, and its ability to withstand extremely high temperatures.

Metals like gold and silver are not used for RTD heat trace because they don’t exhibit the high resistance that is needed, they have low resistivity. Whereas a material like tungsten has high resistance but is very brittle. Copper is often used to make the RTD element as it has low resistivity and is a cheaper metal. The only downside to copper is that is has less linearity.

The maximum temperature of the copper is around 120C. An RTD material is made from either platinum, nickel, or nickel alloys. Nickel wires work well within a certain temperature range but are not linear. The RTD sensor requires a conductor with a high resistivity so a small amount of conductor volume can be used. The resistance should vary as much as possible with temperature.

Construction of a resistance thermometer

The resistance thermometer is put inside a protective tube to keep it from becoming damaged. Platinum wire is wound around a ceramic bobbin to form the resistive element, which is placed inside a stainless or copper steel tube. Lead wire is attached to the element and external lead and covered with an insulated tube to protect against short circuits. Ceramic is an insulator for high-temperature elements, while glass or fibre is used for low-temperature.

How a resistance thermometer works

The tip of the resistance thermometer is positioned near the heat source and heat is evenly distributed across the resistive element. Changes in the resistance vary the temperature of the element and the final resistance is measured.

Linear approximation

Linear estimation is predicting the resistance-temperature correlation using a linear equation. Quadratic approximation is a precise guess of the resistance-temperature connection expressed as a quadratic equation.

Quadratic approximation

Quadratic approximation is a precise guess of the resistance-temperature connection expressed as a quadratic equation.

The resistance thermometer is less responsive, and the material used to make the element is cheaper.

How can TRM help?

If your business manufacturing processes need heat management then temperature monitoring and control will be extremely important to you. Our high-temperature cable and measurement sensors can suit practically any environment in any industry.

The team at TRM are experts in heat management and industrial temperature measurement, offering services relating to design, supply, and installation as well as providing a wide selection of temperature-related products. Contact us today to discuss the specific requirements of your operations and find out how we can help you.

What is a J type thermocouple?

Posted on by Jamie Groves

A J type thermocouple is one of the most common and applicable thermocouple types. The most important thing to know about this thermocouple is that is has a small temperature range and a reduced lifespan if used at higher temperatures. It has positive leg which is made from an iron wire and negative leg consisting of a constantan (copper 55% and nickel 45%) alloy wire. It is the Curie Point of the iron at 770C that gives type J its restricted temperature parameters of -40C-750C. 

If this thermocouple is used in an oxidising environment at a high temperature the iron will change on a molecular level and no longer have its normal voltage output versus temperature. It won’t return when the iron is cooled down either. The cost and dependability of this thermocouple mirrors the type K. However, in order for the J type to work properly reduction atmosphere would be best and it shouldn’t be used at particularly low temperatures either.  

The linearity of a J type thermocouple can vary by -70C across its full range from -210C to 1200C. It has a particularly straight section from 100C to 500C which veers off at around -0.5C. Both the lower and higher ranges can be lengthened with linearity loss.  

Why use a J type thermocouple? 

  • Out of all the different types of thermocouples, type J is the least costly 
  • It provides 1mV output for 18C 
  • It is beneficial in lowering atmospheres 
  • If it is protected by the right mineral insulation and a suitable outer sheath, the J type can be used from 0 to 816C. It isn’t at risk of wear in the 371 to 538C temperature range 
  • It is versatile and can be used for many different applications in industry 

Type J insulation material 

In J type thermocouples, MgO insulation is the main type used due to its many useful features including quick response, small size, wide temperature range, durability, accuracy, thermal shock, and resistance to vibration. This makes it an ideal choice for practically all lab or process uses. Conventional MgO insulation includes ANSI/ASTM standard limits of error conductor material and normal (96%) of pure insulation. 

MgO insulation has initial calibration tolerances at the temperature range of 0 to 750C. Its typical tolerance is +2.2C or +0.75% which is the right fit for J type thermocouples. 

What are the downsides to type J thermocouples? 

  • Can’t be used for temperatures that are over 760C 
  • They have an iron wire in one leg which means it will form rust in humid conditions and the rust can lead to incorrect readings or at worst an open circuit 
  • They can become oxidised, so it is not the right option for damp areas or low temperatures 
  • If used at a higher temperature than 760C there will be a quick magnetic alteration that will cause irreversible recalibrations 

Summary 

J type thermocouples are great for a lot of industry applications, but they have their limitations and in specific cases they won’t be the right fit for the job. If you need help understanding thermocouples and what your business operations need in terms of temperature measurement and control, TRM are here to support you. Contact us today to discuss your needs and our team of specialists will be on hand to implement the right solutions. 

 

What are small modular reactors?

Posted on by Jamie Groves

What are small modular reactors?

Small modular reactors (SMRs) are part of today’s advanced nuclear technology that is made to be more environmentally friendly within the nuclear power sector. They are power generators with an output that is around one-third of what standard nuclear power reactors can produce (approximately 300 MW(e)). SMRs are designed to offer enhanced levels of safety and produce large amounts of low-carbon electricity. The key features of SMRs are:

  • Small- in terms of physical size, they’re a fraction of a traditional nuclear power reactor.
  • Modular- allows systems and elements to be factory-built and moved as a complete unit to a location ready to be installed. This minimises costs, improves quality, and reduces construction schedules.
  • Reactors- they use nuclear fission to create heat and produce energy.

Together with bigger, conventional reactors, and other advanced reactors, small modular reactors are growing nuclear energy portfolio options that are necessary to meet our national standards of energy safety and mitigating climate change.

What are the benefits of SMRs?

Several of the benefits of SMR technology are linked to the foundation of their small and modular design. Thanks to their smaller footprint, they can be installed in locations that wouldn’t be suitable for bigger nuclear power plants. Prefabricated units of small modular reactors can be made, shipped, and fitted on site, meaning they’re more affordable to construct than large power reactors and with the addition of mineral insulated cable, they’re safe from hazards.

Small modular reactors are typically custom designed for a specific location, which can sometimes cause delays in construction. SMRs ensure savings in both construction time and cost, and they can be deployed incrementally to match increasing energy demand.

Some of the difficulties of getting access to energy are infrastructure, restricted grid coverage in rural areas, and the expense of connecting to the grid in rural locations. One power plant shouldn’t represent any more than 10% of the total installed grid capacity.

In locations that don’t have suitable transmission lines and grid capacity, SMRs can be fitted into a grid that’s already there or remotely off-grid, for smaller electrical output, ensuring there is low-carbon power for both industry and the general population. This is especially applicable for microreactors, which are a subset of SMRs and generate electrical power up to 10MW(e).

Small modular reactors are better for the environment in comparison to other SMRs are best suited to areas that don’t have access to clean, reliable, and affordable energy. In addition, microreactors could work as an alternative power supply in emergencies or take the place of generators that are usually run on diesel.

Compared to other reactors, SMR designs are typically less complex, and the safety concept makes use of passive systems and the natural safety characteristics of the reactor, including low power and operating pressure. So, in these cases, no human intervention or external power or force is needed to shut down the systems.

This is due to the fact that passive systems depend on physical actions like circulation, gravity, convection, and self-pressurisation. The improved safety margins and mineral insulated cable, in some cases, eliminate or substantially reduce the potential for dangerous releases of radioactivity into the environment and the public in the event of an accident.

Another benefit of small modular reactors in the nuclear industry is they have reduced fuel requirements. Therefore, power plants that are based on SMRs might need refuelling less often, every 3 to 7 years compared to every 1 to 2 years for standard plants. Some SMRs are even designed to function for up to 30 years without any need for adding fuel.

Sustainable development and the role of SMRs

Small modular reactors and nuclear power plants can offer distinctive attributes relating to efficiency, economics, and flexibility. Whilst nuclear reactors can output electricity according to demand, certain renewables like wind and solar are variable sources of energy that rely on the weather and time of day.

SMRs could work in tandem with and boost the effectiveness of renewable sources in a hybrid energy system. These features enable SMRs to play an important part in the transition to clean energy.

How do we help small modular reactor developers?

At TRM, we provide solutions to modular reactor developers globally with the aim of making sure our clients have the knowledge to design and implement the most suitable, cost-effective, and long-lasting products.

As experienced mineral insulated cable manufacturers this is often what our core products centre around. However, if we feel that it’s not the right fit for the application, we will use other technologies to achieve the desired outcome. Contact us today to find out more.

 

 

What is pipe heat tracing?

Posted on by Jamie Groves

What is pipe heat tracing?

Having a pipe heat trace system is essential for cold weather conditions when the liquid that flows through pipes tend to freeze. If freezing occurs within pipes, it can cause damage to the piping system as a whole. In serious cases, the build-up of pressure in pipes can result in cracks, or the pipes could even blow up, causing serious injuries to anyone near to the system. In this article, we’ll be going into detail on what pipe heat tracing is and how it is used.

What is pipe heat tracing?

Pipe heat tracing (also referred to as heat tracing) is often used to make sure fluid, process, or material temperatures within pipes and piping systems are kept above ambient temperatures during static flow conditions as well as offering additional freeze protection in specific applications.

You can design a customised heat trace system for certain applications by choosing the right type of industrial heat trace cable. Also, it’s possible to control the level of heat generation through these wires by altering the wattage of the heat trace cable to work with particular requirements for processing fluid.

How is pipe heat tracing used?

One of the most commonly used applications for electric industrial heat trace products is to avoid the freezing of pipes. Using self-regulating electric heat trace alongside an ambient temperature sensing system is the most cost-effective and efficient way to protect your pipes from freezing.

The system design for electric pipe heat tracing applications will be affected by several factors. These include pipe size/diameter, liquid temperature/heat loss, number of thermal heat sinks in the run (flanges/valves), and type of insulation. This will help to determine the right amount of power necessary for the applications so an efficient heat trace system can be designed and supplied.

The controls in these types of systems can be very complicated, as often they are process critical. In order to manage this effectively, various features can be designed into your system such as real-time temperature data, backup operations (in the event of a failure), system failure notifications, wireless connectivity, and more. Specific allowances need to be made for tracing water for safety showers and fire protection systems. Also, electric heating cable systems are typically used as backup systems when steam is used as the main source of freeze protection.

Maintaining temperature

Heat tracing can be used to maintain a steady temperature in pipes and tanks of any size and in a lot of different applications. Pipes that have thermal protection can keep liquid at a regular temperature whilst being moved to a different process through the pipes. As well as this they can lower tank heating expenses due to the incoming material not forming a thermal drag on the process.

Removable and reusable insulation jackets and blankets

Removable insulation provides cover for valves, flanges, and other fittings in industrial buildings. They are an effective, convenient, and cheaper solution to lowering heat loss and making your overall operations more efficient. Standard pipe and valve insulation line products are designed to fit various sizes, and can be used on pretty much any application that needs thermal processing such as:

  • Valves
  • Pumps
  • Filters and regulators
  • Pressure reducing valves
  • Strainers

As the cold weather starts closing in, it’s important to make sure you’ve got suitable pipe heat tracing in place to avoid frustrating and expensive problems should your pipes freeze over. Contact TRM today to discuss your heat trace needs. Our specialists are on hand to make sure you get industrial heat trace cables and an overall system that works for your operations.

Everything to know about trace heating

Posted on by Jamie Groves

What is trace heating? 

Trace heating is when the temperature of pipes and vessels is maintained or increased via specifically engineered cables. Trace heating products exist in response to the winter season when temperatures become very cold and can drop below freezing levels. 

When this happens, businesses often look to trace heating as a solution to prevent their vessels and pipes from freezing during the coldest temperatures. This is when pipes can freeze over which might result in them bursting from the expanding ice applying too much pressure. So, the aim of a trace heating system is to stop frost from forming in water pipes by keeping temperatures at a certain level. 

Also, heat tracing can be applied in processes that need temperature maintenance like insulating steam pipes. Another example is where certain liquids need to be kept at a specific temperature so they can be safely transported. In these cases, heat tracing can still be applied even without cold temperatures. 

How does trace heating work? 

Trace heating is done by connecting specifically engineered cables made from a resistance element to the vessel or pipe. The electric cables then have the job of process temperature maintenance by swapping heat loss with their power output. Ohm’s law dictates that connecting a voltage with a wire or cable will lead to a supply of power, which is then changed into heat energy by the heat tracing system. 

Trace heating cables have two copper conductor wires that are the same length, which forms a heating zone with a resistance filament in position. With a supply of fixed voltage, a consistent wattage is generated which in turn heats up the zone. A thermostat monitors the trace heating cables to make sure that the correct amount of thermal energy is produced so the cable won’t underheat or overheat. 

What are the different types of trace heating UK? 

Series resistance trace heating 

A series resistance heating cable is made up of a high-resistance wire that is usually insulated and enclosed within a protective cover. Thermal energy is created from the resistance of the wire when it is powered at s specific voltage level. The main benefit of a series resistance heating cable is that it often costs less than other options and is capable of maintaining very high temperatures for longer lines. 

Therefore, series resistance trace heating cables are normally made to be a fixed length and can’t be shortened in the field. This is because any break or failure at any point along the line would lead the full cable to fail. So, series resistance trace heating cables are often used for longer pipeline heating procedures. 

However, the circuit still needs to be monitored and controlled as the resistance material could melt because of overheating. Series resistance trace heating is normally put in place when long pipeline process heating is required, for example on the quay side of load pipes on oil refineries and along oil pipelines. 

Constant wattage trace heating 

The design for constant wattage trace heating cables includes a heating element that is wrapped around two insulated, parallel wires. There are several points throughout the trace heating cable that experiences constant wattage. 

A notch is made in the insulation on opposite sides of the conductors. Then a small heating circuit is created by fusing the heating component to the exposed conductor wire and this is continued throughout the entirety of the cable. Next the parallel wires are separated from the grounding braid by an inner jacket. 

A key advantage of constant wattage trace heating, compared to series resistance heating, is that the former can still work even in the event of an issue somewhere on the cable. In addition, the length of the cable can be altered on site thanks to its parallel functionality, this cannot be done with series resistance trace heating. It’s for this reason that a lot of businesses and industries ask heat trace specialists to install constant wattage trace heating, because of the flexibility you get with it. 

Constant wattage trace heating cables always come with a thermostat when installed in order to monitor and regulate the power output of the cable. This is done to stop overheating and burning out, should the cable ever come into contact with itself. 

Self-regulating trace heating 

Self-regulating trace heating cables that can change depending on the temperature. On a basic level, when temperatures drop below a certain limit, the cable resistance will go down as well. However, the resistance of the cable will increase when the temperature goes above the specified level. 

Self-regulating trace heating cables are made from two equal wires encased in a semi-conductive polymer. The polymer is typically made with carbon which stops the current from overflowing at increased temperatures. The carbon inside the polymer can expand or contract to generate different levels of resistance and heat energy output. 

The length of the cables can be altered in the field. Also, the self-limiting capability of the cable enables it to be more energy efficient as it can lower its output at higher temperatures. Thanks to its feature of conserving energy when the temperature goes up, self-regulating cables can help businesses to save money as less power is used. 

Additionally, these cables have better levels of safety which is particularly desirable in hazardous locations. This is because the power output of the cables won’t go above a certain level as output decreases when the temperature increases. So, it’s not possible for the cables to overheat, which could have been dangerous, especially in areas with flammable gases and vapours. 

How can trace heating be applied? 

Freeze protection 

As previously mentioned, trace heating is often used to protect pipes and vessels from freezing by keeping the temperature at a set level above freezing point. This is done by providing heat energy to balance the level of heat lost through conduction. Keep in mind thermal insulation can only slow down the heat loss process, it can’t prevent it from happening completely. So, trace heating is a good solution to heat loss and frost protection. 

Gutter and de-icing roof 

Trace heating cables can be fitted to the roofs and in gutters to avoid the accumulation of ice or snow. Also, the cables function as a draining path for water from the melted ice to move through to stop overflowing in the rooftops and gutters. 

Overflowing can have a negative effect on the structural integrity of buildings as it can lead to water soaking into cracks or joints. Additionally, the extra weight from the gathering of snow or melted ice can cause indentations and depressions on the rooftops and gutters. So, trace heating is key to preventing unwanted water build-up. 

Anti-cavitation 

Trace heating helps to lower the chance of cavitation occurring in pipes as heating a liquid makes it thinner and reduces its viscosity. The term cavitation refers to the development of vapour bubbles in a liquid caused by fast changes in pressure.  

Shockwaves are created when the vapour bubbles or cavities in the liquid collapse or implode, which degrades the inside of the pipe over time. Also, cavitation can break up the flow of liquid within the pipes. So, putting heat tracing cables in place will lower the likelihood of cavitation as it helps to reduce the pressure difference in the liquid. 

Conclusion 

Thermal insulation doesn’t completely reduce heat loss, so heat tracing is needed for businesses to keep temperatures over a designated level. This is particularly important during the winter season when temperatures can go below freezing levels and frost heaving is likely to happen. 

As professional trace heating suppliers, TRM can help you with your trace heating needs. Contact our team today to discuss your requirements. 

 

What are the different types of temperature sensor?

Posted on by Jamie Groves

It may not seem like a common thing, but we use temperature sensors every day to control the temperature in buildings, water temperature regulation, and to control refrigerators. Temperature sensors are also an essential part of several other applications including consumer, medical, and industrial electronics. In this article, we’ll be looking at each type of industrial temperature sensor in detail as well as their advantages and disadvantages. 

Thermocouples 

A thermocouple is the most commonly used type of temperature sensor. Thermocouples are widely utilised in industrial, automotive, and consumer applications. One of the key benefits of thermocouples is they are self-powered and don’t require any excitation, so they can work over a broad temperature range and have fast response times. 

Thermocouples work by attaching two dissimilar metal wires together, which causes a Seebeck Effect. The Seebeck Effect is where a temperature difference of two dissimilar conductors creates a voltage difference between the two substances. This voltage difference can then be measured and used to work out the temperature. 

There are many types of thermocouple sensors made from various materials, allowing for different temperature ranges and sensitivities. The types of thermocouples are distinguishable by the letters they are assigned. The one that is used most often is the K type. Despite there being many benefits to thermocouples, making them a frequently used temperature sensor, they do come with a few small disadvantages too. 

For example, measuring temperature can be difficult because of their small output voltage, which demands accurate amplification, exposure to external noise across long wires, and cold junction. Cold junction is the term used to describe the thermocouple wires meeting copper traces of the signal circuit. Another Seebeck Effect is created from this which needs to be compensated for with cold junction compensation. 

Resistance Temperature Detector (RTD) 

When temperature changes, the resistance of metal changes too. It is this difference in resistance that the concept of RTD temperature sensors was based on. An RTD is a resistor that has clear resistance vs. temperature features. The most common and precise metal used to make RTDs is platinum. 

Platinum RTDs are often utilised because they provide an almost linear response to temperature alterations, they are stable and reliable, they offer repeatable responses, and they have a vast temperature range. Resistance temperature detectors are mostly used in applications that require precision due to their high accuracy and easy repeatability.

RTD heat trace elements typically have increased thermal mass, and so don’t respond as quickly to changes in temperature as thermocouples do. Signal conditioning is key in RTDs. They also need an excitation current to flow through the resistance temperature detector, if you know the current, you can work out the resistance.

Configurations of RTDs can come in two, three, and four wire options. The two-wire is best used when the lead length is short enough that resistance doesn’t negatively impact measurement accuracy. 

A three-wire configuration includes an RTD probe that moves the excitation current. This offers a way to cancel wire resistance if necessary. Four-wire is the most accurate approach, as separate force and sense leads take away the effect of wire resistance.

Thermistors 

Thermistors share similarities with RTDs in the sense that temperature fluctuations cause resistance changes that can be measured. Thermistors are often manufactured from a polymer or ceramic material. In many cases, they are less expensive than RTDs but also aren’t as accurate. The majority of thermistors come in two wire configurations. 

The NTC (Negative Temperature Coefficient) thermistor is the most used for temperature measurement applications. The resistance of an NTC thermistor decreases as the temperature rises. Also, thermistors have a non-linear relationship with temperature resistance. A common way or using a thermistor, is by using it with a fixed value resistor to create a voltage divider with an ADC digitised output. 

Semi-conductor based ICs 

There are two different types of semi-conductor based temperature sensor ICs: local temperature sensor and remote digital temperature sensor. Local sensors are ICs that measure their own die temperature using the physical characteristics of a transistor. Remote digital sensors record the temperature of an external transistor.

Local temperature sensors can utilise analogue or digital outputs. Analogue outputs can only be either voltage or current whilst digital outputs can be seen in many formats. Local sensors feel the temperature on printed circuit boards or the natural air around it. 

Remote digital sensors work like local ones by using the actual features of a transistor. The difference with remote digital is the transistor is situated away from the sensor chip. Certain microprocessors and FPGAs have a bipolar sensing transistor to record the die temperature of the desired IC. 

Final thoughts 

Each of these types of temperature sensors has its own unique features and benefits that will best fit with different applications. Thermocouples are cheap, durable, and are able to measure a wide range of temperatures. RTDs provide a wide range of measurements as well as measurements that are accurate and repeatable, but they are slower, and they need an excitation current and signal conditioning. 

Thermistors are small and durable, but they aren’t as accurate as RTDs and demand more data corrections to translate temperature. Semi-conductor based ICs are open to implantation and can come in very small packages, but their temperature range is limited. 

For all your temperature sensor and heat trace needs, contact TRM today. Our specialist team are on hand to ensure your application needs are perfectly met. 

  

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