DTSX200 Distributed Temperature Sensor

Measurement Principle

Operating Principle

Yokogawa DTSX200 measures temperature and distance over the length of an optical fiber using the Raman scatter principle. A pulse of light (laser pulse) launched into an optical fiber is scattered by fiber glass molecules as it propagates down the fiber and exchanges energy with lattice vibrations. As the light pulse scatters down the fiber optic cable, it produces stokes signal (longer wavelength) and anti-stokes (shorter wavelength) signal, of which both signals shifted from the launch of the light source. The intensity ratio of the two signals components depends on the temperature at the position where the Raman scatter is produced. This temperature can thus be determined by measuring the respective intensities of the stokes and anti-stokes signals. Furthermore, part of the scattered light, known as the backscatter, is guided back towards the light source. The position of the temperature reading can thus be determined by measuring the time taken for the backscatter to return to the source.

Raman Scattering

All light interacts with matter! For example, imagine standing in a pitch black garage with no external light source. Inside this garage is a bright red sports car. Needless to say, you cannot see the sports car or the color of the sports car itself. However, when you turn on the lights to the garage, you can immediately see the light source reflecting the bright red color off the car. The light that is bouncing off the red sports car is only bouncing off the "red" spectrum, therefore, your eyes see the sports car as, well, red.

Types of Scattering Light

Yokogawa's distributed temperature sensors measure temperature distribution using Raman scattering light, which exhibits particularly good temperature sensitivity among the following types of scattering light.

Measurement Method

Single-Ended Measurement Method

• This method launches optical pulses into only one end of the optical fiber for sensing. Easy to install, it is effective when the measuring target is long range.

Double-Ended Measurement Method

• This method launches optical pulses into both ends of a looped optical fiber for sensing.
• This method allows for continued measurement even if on place of the fiber optic cable is broken.

Comparison of Measurement Methods

Types of Temperature Sensors

Types of Temperature Sensors and Their Features

Comparison among Temperature Monitoring Methods

	Fiber Optic Sensor	Thermo Camera	Point Sensor (Thermocouple)
Description	Wide-area monitoring based on a fiber optic sensor	Surface temperature monitoring based on a thermo camera	Multipoint monitoring based on discrete sensors
Detection Method	Contact	Non-contact	Contact
Range of Temperatures Monitored	-200 to 300 °C (Based on a sensor cable)	Normal temperature to 2000 °C (Range switching required)	-200 to 1000 °C (Type K thermocouple)
Area	Coverage of a very wide area DTSX200: up to 6 km / ch DTSX3000: up to 50 km / ch DTSX1: up to 16 km / ch	Small viewing angle of 20°	Wide area
Advantages	Coverage of a very wide area and seamless monitoring	Capability of a limited tiny area monitoring	Capability of a limited tiny area monitoring
Disadvantages	Restricted to small areas	Non-seamless monitoring	Non-seamless monitoring Installation and maintenance of compensating lead wires

Performance

Representative parameters that indicate the performance of distributed temperature sensors include the spatial resolution and temperature resolution. In spite of the fact that in general, there is a trade-off relationship between these parameters, we have realized high performance based on signal processing technology.

Spatial Resolution

• The spatial resolution is the minimum length that detects changes in temperature (it is also referred to as the response distance).
• The spatial resolution is defined as the length when a temperature change of 10 to 90 percent of the optical fiber for sensing is detected.
• The sampling resolution represents the data interval, the definition of which is different from that of the spatial resolution.

Temperature Resolution

• The temperature resolution is defined by the standard deviation (1 σ) of measured values along the fiber optic sensor in a uniform temperature environment (in a thermostat chamber).
• The temperature resolution is the indicator of variations, which does not indicate temperature accuracy (the use of a reference thermometer in calibration makes it possible to make measurements with a higher temperature accuracy).
• Raman backscattering light is a very faint signal. By repeating measurements to average measured values, the distributed temperature sensors achieve a higher temperature resolution.

Examples of measurement results (DTSX200)

Types of cables

You can choose the most suitable type according to your intended use.

Normal Operating Temperature	Applications	Cable Type	Cable Details	Features
Normal Temperature	Conveyor Fire Detection Cable Temperature Monitoring Bus Duct Temperature Monitoring Cable Tunnel Fire Detection Warehouse Fire Detection Hot Spot Detection Cold Spot Detection etc.	Standard Type	Image Zoom	Nonmetal, lightweight, and easy to install EN 54-22 certified
		Robust Type	Image Zoom	Resistant to crush and tension and less likely to break EN 54-22 certified
		Flexible Type	Image Zoom	Thin and flexible and easy to install along the measurement targets
High / Low Temperature	Blast Furnace Monitoring Drying Furnace Monitoring LNG Leak Detection Well Monitoring etc.	Steel Tube Type	Image Zoom	Thin and flexible and easy to install along the measurement targets
		Steel Armored Type	Image Zoom	Resistant to crush and tension and less likely to break

Product Introduction

DTSX200 Overview

The DTSX200 distributed temperature sensor is configured by a DTS module, an optical switch module, a base module, a power supply module, and so on.

* DTS : Distributed Temperature Sensor

The distance to the target : 6 km Range

On the Partner Portal Member Site, you can check the details of the specifications.
GS 39J06B45-01 : DTSXM Distributed Temperature Sensor Middle Range System
GS 39J02B45-01 : DTSXM Distributed Temperature Sensor Middle Range System (Software)

Optical Switch Module

Base Module

Power Supply Module

Accessory

DTRK10 Rack Mount Kit

Software

DTSX3000 Control Visualization Software (DTAP3000)

DTSX200 data conversion software (DTAP200D)

Specifications

Refer to the General Specifications for detailed specifications.

DTSX 200

Temperature calibration of the Sensor Optical Fiber for DTSX200 is required before temperature distribution measurement.

Optical Switch Module

Note:  As a guideline, the module should be replaced periodically every 4.7, 6 and 9.5 years for continuous operation of 15-second, 20-second and 30-second measurements, respectively.

REGULATORY COMPLIANCE and CONFORMITY to STANDARDS

Note: Under EU legislation, the manufacturer and the authorised representative in EEA (European Economic Area) are indicated below:
Manufacturer: YOKOGAWA Electric Corporation (2-9-32 Nakacho, Musashino-shi, Tokyo 180-8750, Japan).
Authorised representative in EEA: Yokogawa Europe B.V. (Euroweg 2, 3825 HD Amersfoort, The Netherlands).

Industries/Applicantions

Vehicle Lithium-ion Battery

Smart Monitoring of Manufacturing Process Shelves and Storage Shelves

Thermal runaway of lithium-ion batteries mounted on individual shelves is discovered at an early stage. This enables a quick initial response when an abnormality occurs to limit damage to a minimum.
(For details, refer to "Smart Monitoring of Manufacturing Process Shelves and Storage Shelves -In-vehicle Lithium-ion Battery Applications- ".)

Prevention of Fires in Exhaust Air Ducts in Battery Assembly Process

Fires or dust explosions in exhaust air ducts for preventing the contamination of aluminum dust in the assembly process of lithium battery batteries are monitored. Abnormalities are not overlooked as ducts extending over long distances in blind areas such as roof space are comprehensively monitored. (For details, refer to “Prevention of Fires in Exhaust Air Ducts in Battery Assembly Process -In-Vehicle Lithium-ion Battery Applications- ".)

Monitoring of Soundness of Power Supply Bus Bar

The joints of the power supply bus bar are monitored.
Abnormalities are not overlooked as fiber optic cable is built into the bus duct and bus bars extending over long distances in blind areas such as roof space are comprehensively monitored.
(For details, refer to "Monitoring of Soundness of Power Supply Bus Bar -In-vehicle Lithium-ion Battery Applications-".)

Fiber Optic Cable Visualizes In-furnace Temperature Distribution

The DTSX fiber optic distributed temperature sensor can monitor temperature distribution every meter along the path of the fiber optic cable.
Thermocouples, etc. are used for heater control as up till now, and by adding DTSX to them, it will be possible to visualize the temperature distribution inside the entire drying furnace.
Resolving heater and other problems by utilizing the result, and passing products through the furnace after setting the in-furnace temperature to the ideal temperature profile result in improved productivity.

When attempts are made to measure multiple points by thermocouples, etc., wiring is complicated, construction costs escalate and periodic maintenance of each individual sensor is required. This is unrealistic when applying it to multiple drying furnaces.
As the DTSX system requires only laying fiber optic cable inside the furnace, both initial and running costs can be reduced.
Moreover, a single DTSX can cover multiple drying furnaces, which improves cost effectiveness.
The DTSX has also been put to use in monitoring the temperature distribution in tunnel furnaces.
(For details, refer to "Fiber Optic Cable Visualizes In-furnace Temperature Distribution".)

Fire Detection

Early fire detection to critical process and environment is an important component to any safety system. A blazing fire has devastating consequences to important assets, products and most importantly, human lives. Furthermore, the cost of downtime due to fire leads to lost opportunities and costly repairs. Discrete sensor technology often fails due to the surrounding environment conditions such as dust, humidity, heat and corrosion. In addition, it is expensive to maintain a conventional sensor technology due to constant repair. Yokogawa's DTSX200 is designed to detect fire in critical assets under the most extreme conditions and offers unmatched reliability, performance and cost savings.

Yokogawa's DTSX200 is designed to deploy in the following fire detection applications:

• Conveyor belts carrying important goods
• Tank farms
• Cable trays
• Underground tunnels
• Pipelines (underground, above ground)
• Nuclear facilities
• Mining, Refinery

* Assuming appropriate scan rate and data refresh intervals are used

Oil & Gas

The development of unconventional resources, such as heavy oil, oil sands and shale gas has been progressing in line with the increase in global energy demand. DTSX200 can measure the temperature distribution along an optical fiber with a length of several kilometers are being applied to extraction of unconventional resources. DTSX200 maximizes oil/gas extraction by providing real time continuous temperature measurement through different injection dynamics. In addition to well optimization, DTSX200 provides critical data that help monitor and detect wellbore conditions for leaks, water penetration and gas breakthrough. DTSX200 also provides control capability (measurement of flow, pressure, temperature, valve position, etc.) on top of fiber optic temperature measurement. More importantly, compared to conventional wellbore monitoring technology, DTSX200 is more robust, cost effective and accurate.