Embedded temperature detectors

In HT motors the terminal box for space heaters and embedded temperature detectors must be separate from the main terminal box. 

All bearings of HT motors must be provided with embedded temperature detectors (ETDs). 

Embedded temperature detector (ETD) method-this method is used for stator windings of 5000 kW and above as in lEC 600.54-1. 

Embedded temperature detectors are resistance temperature detectors (RTDs) or resistance thermometers or thermocouples, built within the machine during manufacture at points that are not accessible when the machine has been assembled. This method is generally employed for the likely hot spots of a machine such as the slot portion and the overhangs of the stator windings. 

This method is applicable where neither the embedded temperature detector nor the resistance method is... 

This is a later introduction in the sensing of temperature compared to the more conventional types of temperature devices available in an embedded temperature detector (ETD), such as a thermocouple or a resistance temperature detector (RTD) described below. Thermistors can be one of the following types ... 

Temperature detectors embedded in the motor winding give close, accurate indication of motor temperature. Both conventional resistance temperature detec tors (RTD) and special thermistors (highly temperature-sensitive nonlinear resistors) are used. With appropriate auxiliaries these devices can indicate or record motor temperature, alarm, and/or shut down the motor. 

It is recommended that the motor should have separate terminal boxes for the main supply and for the accessories such as space heaters, embedded teinpertiture detectors, bearing temperature indicators and moisture detector terminals, etc. In LT motors, however, if it is not possible to provide a separate terminal box for these accessories, the main terminal box may be adequately spaced to segregate the.se terminals from the main terminals within the box. 

Until recently, temperature measurements in microfluidic systems were limited to measures of bulk fluid temperature at the inlet and outlet of microfluidic sections or simply measurement of the substrate temperature. With regard to local temperature measurements, thermocouple probes provide highly accurate measures of fluid and/or substrate temperature with excellent temporal response. However, thermocouples can often be physically intrusive and generally suffer from poor spatial resolution since most probes have a characteristic size of several micrOTs or more. Alternatively, microfluidic devices can be fabricated with integrated microscale resistance temperature detectors (RTDs s) embedded in the substrate with spatial extents on the order of a few microns [13]. Micro-RTDs overcome the intrusiveness issues of thermocouples however, their fabrication can be quite complex and RTDs still suffer from poor spatial resolution which limits their ability to resolve local thermal... 

At least six detectors are built within the machine, suitably distributed around the circumference and placed between the layers along the length of the core where the highest temperature is likely to occur. Each detector is installed in intimate contact with the surface, whose temperature is to be measured and in such a way that the detector is effectively protected from contact with the cooling air. A detector embedded beneath the winding layer inside the slot is of little consequence for it will detect the temperature of the core and not of the winding. The location of the detectors must be as follows ... 

Note The embedded lemperalure deleclor melhod is inappropriate for stator windings, which have only one coil side per slot, in such ciises the resistance melhod must be used with the same limits of temperature rise. For checking the temperature of such a winding in service, an embedded detector at the bottom of the slot is of little use because it would give mainly the temperature of the iron core. A detector placed between the coil and the wedge will follow the temperature of the winding much more closely and is, therefore, better for check tests, although the temperature there may also be a little less than the actual one. 

The TID design proposed Patterson consists of an alkali metal doped cerwlc cylinder, containing an embedded heater surrounded by a cylindrical collector electrode [100]. The ceramic thermionic emitter is biased at a negative potential with respect to the collector electrode, and it is heated to a surface temperature of 400-800 C, depending on the mode of detection. The response of the detector to different elements depends on the electronic work function of the thermionic surface (i.e., the... 

Zsolnay and Kiel [26] have used flow calorimetry to determine total hydrocarbons in seawater. In this method the seawater (1 litre) was extracted with trichlorotrifluoroethane (10 ml) and the extract was concentrated, first in a vacuum desiccator, then with a stream of nitrogen to 10 pi A 50 pi portion of this solution was injected into a stainless steel column (5 cm x 1.8 mm) packed with silica gel (0.063-0.2 mm) deactivated with 10% of water. Elution was effected, under pressure of helium, with trichlorotrifluoroethane at 5.2 ml per hour and the eluate passed through the calorimeter. In this the solution flowed over a reference thermistor and thence over a detector thermistor. The latter was embedded in porous glass beads on which the solutes were adsorbed with evolution of heat. The difference in temperature between the two thermistors was recorded. The area of the desorption peak was proportional to the amount of solute present. 

The thermal conductivity (TC) detector consists of four filaments embedded in a stainless-steel or brass block which acts as a heat sink. The TC detector is extremely sensitive to temperature changes and should be insulated to prevent temperature excursions during the time in which it takes to complete an adsorption or desorption measurement. Long-term thermal drift is not significant because of the calibration procedure discussed in the next section and therefore, thermostating is not required. 

This is why TC detectors are made of cells mounted closely together, embedded in metal, with the assembly meticulously insulated. In spite of this effort, the cells are not exactly matched in heat transfer to the metal they are embedded in. This means that it is important to control the temperature of the detector body accurately. In most modern instruments, the TCD tempera-control circuit produces much better thermal stability (though not necessarily accuracy) than even the chromatographic oven control. 

The heat of adsorption detector, devised by Claxton, consists of a small plug of adsorbent, usually silica gel, through which the chromatographic eluent passes subsequent to leaving the column. Embedded in the silica gel is either a thermocouple or a thermistor that continuously measures the temperature of the adsorbent and mobile phase. 

A modiHcation of the alkali metal salt flame ionization detector is the thermionic detector. Instead of a flame, a low-temperature H2 plasma is used. The alkali metal salt is embedded in a ceramic matrix which is heated to about 600-800 °C. P or N containing radicals and ions... 

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