Electronical Temperature Sensors

Temperature is one of the most measured physical parameters. Despite this, precise temperature measurement is one of the most difficult tasks in motor technology. To meet the constantly increasing requirements for improved motor performance, higher efficiency and reduced emissions, it is necessary to use reliable and precise sensors in modern motor control systems. The increased requirements over the last few years regarding measurement accuracy and reliability of temperature measurements has meant that many equipment operators must reconsider the suitability and performance capacity of their temperature measurement equipment. Resistant thermometers can be used between -200 °C and +850 °C. An important common property is that their output parameters are available in the form of electric signals that can be relatively easily transferred to measurement and control instruments for processing, storage and display.

The electronic temperature switch of BEDIA is fitted with thin-film resistor Pt 1000 in a bridge circuit. This sensor element provides close switch point tolerances and a quick response. Switch point and reset hysteresis may be selected within the admissible operating range when ordering so as to allow the monitoring of both very wide and very close temperature ranges. The switching output is protected from short-circuit and overload. The short-circuit current is limited by the output transistor switching off inthe event of a fault. It will automatically reset as soon as the fault has been remedied. The switch is available with ground-connected, plus-connected or potential-free DC switching output. The switch is open in the event of power failure or disconnection of the power supply, independed of the switching function. It is available both as normally open (NO) or normally closed (NC) switch.

These high-power bimetal operated temperature switches are available either with normally closed (NC) or normally open (NO) contact configuration. The robust round metal enclosure accommodates a resilient preloading disk, a bimetal disk and a silver contact. The compact switch system is covered by means of a plate which also carries a silver contact and is isolated from the enclosure by means of an isolating washer. The resilient preloading disk ensures excellent performance. The resilient preloading disk keeps the contact pressure constant throughout the entire temperature range of the BEDIA switch until switching occurs. The mechanically and electrically unloaded bimetal disk snaps over at a preset temperature, with either opening or closing the contact arrangement. The bimetal will only snap back to its initial condition after the temperature has dropped significantly.

BEDIA level monitoring sensors are used to monitor the filling levels of liquids. The sensors detect when a filling level is exceeded or falls below a limit. Water-based liquids like coolants, AdBlue®, fresh water, waste water, bilge water and oil-based liquids like motor oils, hydraulic oils, fuels and brake fluids can be monitored. Since they contain no mechanical moving parts, their function will not be influenced by dirt particles or other influences. No electrical current is sent through the medium via an electrode with BEDIA sensors, an electrolysis of the medium is not possible. Operating Principle The function of the sensor is based on the capacitive principle. It detects the change in capacitance that occurs when an electrode surrounded by air is immersed into a liquid medium. This change in capacitance at the electrode of the sensor excites an oscillator. This signal is processed by a microcontroller-based evaluation circuit which activates or deactivates an output stage.