Point temperature sensors measure the locations where you installed them. DTS measures continuously along a fibre route. The choice is not about which technology is better — it is about whether you can name the locations you need to watch, and whether you can physically reach them.
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Call +86 130 4890 6506 for selection guidance and comparable project types Email usPoint temperature sensing covers thermocouples, resistance temperature detectors, and wireless sensor pucks. Each device reports the temperature at one location. Your coverage is therefore exactly the set of places you bought and installed a device for — no more and no fewer. This is a strength as much as a limitation: the measurement is where you decided it should be, and it is easy to explain to an auditor.
Distributed temperature sensing (DTS) uses an optical fibre as the sensor. One instrument connected to one end of the fibre reports temperature continuously along its length. Coverage is not a count of devices; it follows the fibre route. What limits the detail is the instrument's averaging length, not the number of sensors purchased.
The practical difference shows up when something goes wrong somewhere you did not instrument. A point-sensor installation reports nothing there, because there is no sensor there. A DTS installation reports a value at every point along the fibre — including at the location of a fault nobody predicted.
With one condition that decides whether any of this works, and which is worth stating before anything else: a DTS reading describes the asset only where the fibre is installed close enough to it to share its thermal environment. Fibre lying in a different duct, on a tray above, or in open air a metre away measures its own surroundings, not the cable's. "The fibre passes it" is not the same as "the fibre tracks it". Every DTS project that disappointed its owner usually traces back to this.
| Dimension | Point temperature sensors | Distributed temperature sensing (DTS) |
|---|---|---|
| Coverage | Discrete — one location per device | Continuous along the whole fibre route |
| What sets the detail | How many devices you buy and install | The instrument's spatial resolution, fixed by its optical design; the sampling interval is a separate setting |
| Unpredicted locations | Not measured — nothing was installed there | Measured where the fibre is installed close enough to the asset to track its temperature |
| Hard-to-reach areas | Each point needs to be accessible for installation and service | One fibre can be routed through areas you cannot easily visit |
| Response time | Generally fast at the point being measured | Slower — measurement time is traded for coverage and signal quality |
| Localisation of a fault | To the nearest installed sensor | To a distance along the fibre |
| Adding a measurement later | Add a sensor and its cabling | Requires spare fibre or new fibre — plan for it up front |
| Accuracy | Specified per device; can be very good, including traceable calibration | Depends on the device, its calibration and the installation; detecting change is more robust than quoting absolute truth |
| Cost structure | Scales with the number of locations | Largely independent of how many locations the route passes |
| Electromagnetic environment | Depends on the sensor type; signal wiring and transmitters are affected by interference | The fibre itself is immune to electromagnetic interference — the interrogator is electronic equipment and is not |
| Data volume | Small and easy to handle | Larger, since a profile is produced for the whole route |
| Best fit | A few specific locations that are known and reachable | A long route with many locations, or locations that cannot all be reached |
This table describes the two approaches, not any particular product. Numbers are deliberately absent: any figure worth comparing depends on the specific device and the specific installation, and quoting one would turn a fair comparison into a specification claim.
It is worth being direct about this, because DTS is often proposed for jobs it does not suit.
When the locations are known and few. If the question is "is this bearing, this bushing or this cabinet overheating", a point sensor answers it directly, and for a small number of points it is usually the simpler and cheaper option.
When something must be measured fast. Point sensors are generally quicker to report at the location being measured. Where the requirement is a tight response time, this matters more than coverage.
When traceable absolute accuracy is the point. Some compliance and test applications need a calibrated measurement with a documented chain. That is a well-established strength of conventional sensors.
When you want the simplest thing that works. One sensor, one reading, one place to look. Complexity is a cost even when it is not on the invoice.
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When the route is long and the locations are many. The cost of a DTS installation is dominated by the fibre run and the instrument rather than by how many locations the route passes. That is what makes it competitive once the number of interesting places along the route is large — and why the comparison stops being a per-device price check.
When you cannot predict where the problem will be. This is the strongest argument for DTS. A hotspot at an unpredicted joint is measured, provided the fibre was installed close enough to the cable to share its thermal environment — whereas a point-sensor installation would have had to guess.
When the locations are hard to reach. A cable tunnel, a duct bank or a buried route does not need to be visited at every measurement location after commissioning.
When the environment is electrically noisy. The sensing medium is glass. Interference that would trouble signal wiring does not affect the fibre.
If the first of those describes your route, the cable and tunnel temperature monitoring page describes what the monitoring layer does with the profile once it exists.
Work backwards from the failure you are trying to catch, not forwards from the technology.
What to avoid is choosing by default: buying DTS when a handful of point sensors would have done, or extending a point-sensor scheme along a route where the interesting locations cannot all be enumerated in advance.
No — they answer different questions. Point sensors measure the locations you installed them at; DTS measures continuously along a route. Which is better depends entirely on whether the places you need to watch are known, few and reachable.
There is no single conversion figure, because a point sensor measures a location and DTS measures along a line. A point sensor is useful over a small region around itself — a joint, a termination, a short cable section — so covering a route end to end that way means one device per region, each with its wiring, power and maintenance. On a kilometre-scale route that is thousands of devices. That count, rather than a per-device price, is what usually decides the question.
Yes, and it is often the right answer. Use DTS for coverage of the route and a small number of point sensors where you need fast response or a traceable absolute measurement.
They are not measured on the same basis. A well-calibrated point sensor can give a very good absolute reading at its own location. DTS gives a profile along a route, and how close those values sit to absolute truth depends on the device, its calibration and the installation. For most condition-monitoring purposes, detecting a change from normal behaviour is more useful than debating absolute accuracy.
The fibre is, because it is glass and carries light rather than an electrical signal. The interrogator is electronic equipment and is subject to the same environment as any other instrument. So the sensing path is immune; the ends are not.
Physically, yes, but the fibre has to be installed along the route, which is usually the expensive and disruptive part. If continuous coverage is plausible in future, it is worth laying spare fibre while the route is already open rather than revisiting it later.
It depends on the two questions above: how many locations matter, and whether you can predict them. Where the concern is a hotspot at an unknown joint along a long route, continuous coverage is the reason to choose DTS. Where the concern is a small number of known, accessible terminations, point sensors may be enough.
If you are weighing continuous coverage against a set of known points, tell us the route and the failure you are trying to catch. We will tell you which approach fits — including when the answer is that a handful of point sensors is all you need.
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