Signal temperature sensors

Modern subsea trees, manifolds, (EH), etc., are commonly controlled via a complex Electro-Hydraulic System. Electricity is used to power the control system and to allow for communication or command signalling between surface and subsea. Signals sent back to surface will include, for example, subsea valve status and pressure/ temperature sensor outputs. Hydraulics are used to operate valves on the subsea facilities (e.g. subsea tree and manifold valves). The majority of the subsea valves are operated by hydraulically powered actuator units mounted on the valve bodies. 

Err" signal errors are automatically shown on the LED display in the case of a defective pH electrode or faulty temperature sensor (Pt 100) and for incorrect buffer two set points can be set over any part of the pH, mV or 0° C scale, which when exceeded starts an alarm and/or allows readjustment of dosing valves or pumps via an interface circuit. 

Fig. 3.7 shows a comparison between a capillary thermostat in the right part of the figure and the ever more frequently used NTC temperature sensor whose analogue electrical signal can easily be processed by an electronic control system. The NTC sensor type is increasingly used, particularly in modern European machines that always have their own heater element and sometimes also an additional hot water connection. 

Z. Y. Zhang, K. T. V. Grattan, and A. W. Palmer, A novel signal processing scheme for a fluorescence based fibre-optic temperature sensor, Rev. Sci. Instrum. 62(7), 1735-1742(1991). 

A problem of the calorimetric sensing mode is its cross-sensitivity to changes in ambient temperature. The realization of an additional temperature sensor on the bulk chip solves this problem. The signal-to-noise ratio of the calorimetric mode... 

This chapter includes two different sensor system architectures for monolithic gas sensing systems. Section 5.1 describes a mixed-signal architecture. This is an improved version of the first analog implementation [81,91], which was used to develop a first sensor array (see Sect. 6.1). Based on the experience with these analog devices, a complete sensor system with advanced control, readout and interface circuit was devised. This system includes the circular microhotplate that has been described and characterized in Sect. 4.1. Additionally to the fabrication process, a prototype packaging concept was developed that will be presented in Sect. 5.1.6. A microhotplate with a Pt-temperature sensor requires a different system architecture as will be described in Sect. 5.2. A fully differential analog architecture will be presented, which enables operating temperatures up to 500 °C. 

The voltage drop across the platinum temperature sensor is small since the platinum resistor has a nominal resistance of only 75 Q. The fully-differential LNA amplifies the minute voltage drop in order to provide an useful feedback signal to the differential-analog proportional controller. A simplified schematic of the fully-differential low-noise amplifier is shown in Fig. 5.18. 

The temperature sensor is located in the microhotplate center (J2x, 10 kO nominal). This polysilicon resistor is biased with a temperature-independent current source (/bias)- The voltage-drop across the polysilicon temperature sensor provides the feedback signal for the temperature controller. 

Figure 10.2h gives a sketch of the feedback control system and a block diagram for the two-heated-tank process with a controller. Let us use an analog electronic system with 4 to 20 mA control signals. The temperature sensor has a range of 100°F, so the Gj transfer function (neglecting any dynamics in the temperature measurement) is... 

These tests check the integrity of measurement chains between the sensor and the equipment as well as along the measurement chain. For example, a temperature signal carried over by a current loop is checked against the exact temperature level and the exact conversion levels on the current loop. However, if the temperature sensor contains its own local temperature indicator, this indication will be compared to the temperature available on the control system. 

R 18] [A 1] Each module is equipped with a heater (H3-H8) and a fluidic cooling (C03-C06). Temperature sensors integrated in the modules deliver the sensor signals for the heater control. Fluidic data such as flow and pressure are measured integrally outside the micro structured devices by laboratory-made flow sensors manufactured by silicon machining. The micro structured pressure sensor can tolerate up to 10 bar at 200 °C with a small dead volume of only 0.5 pi. The micro structured mass flow sensor relies on the Coriolis principle and is positioned behind the pumps in Figure 4.59 (FIC). For more detailed information about the product quality it was recommended to use optical flow cells inline with the chemical process combined with an NIR analytic or a Raman spectrometer. 

For the precise measurement of gas flow (steam) at varying pressures and temperatures, it is necessary to determine the density, which is pressure and temperature dependent, and from this value to calculate the actual flow. The use of a computer is essential to measure flow with changing pressure or temperature. Figure 10 illustrates an example of a computer specifically designed for the measurement of gas flow. The computer is designed to accept input signals from commonly used differential pressure detectors, or from density or pressure plus temperature sensors, and to provide an output which is proportional to the actual rate of flow. The computer has an accuracy better than +0.1% at flow rates of 10% to 100%. 

---