OEM customer/projects

This type of multi-gas sensors monitors the condition of high-power transformers and enables early damage detection. The operator can thus initiate maintenance or repair at an early stage. Thus, facilities are protected against damage and uninterrupted electrical power supply is ensured.

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Online Monitoring of Power Transformers

Oil is used as insulating material in high-performance transformers. Over time, electrical and thermal stress can develop fault conditions in the transformer, resulting in the formation of so-called fault gases. These dissolve in the oil, so that oil analyses allow conclusions about the condition of the transformer. For example, up to seven different fault states of the transformer can be distinguished by the concentration ratios of the gases methane (CH4), acetylene (C2H2) and ethene (C2H4), using the Duval triangle (Figure 1).

m-u-t has exclusively developed sensors for a leading global manufacturer of Online Dissolved Gas Analyzers (DGA), for monitoring transformers in high and extra-high voltage networks. At the request of our customer, sensors for measuring up to ten different gases were developed and manufactured in series.

For this application, m-u-t is manufacturing different types of multi-gas sensors in series. These sensors have up to nine optical channels for measurement according to the NDIR method, supplemented by sensors for temperature, relative humidity and pressure and, depending on the type, sensors for hydrogen (H2) and oxygen (O2). 

All types of our multigas sensors integrate all parameter measurements in a single compact sample chamber. Core product advantages of these innovative multi-gas sensors, developed and manufactured in Germany, are the compact design and the attractive pricing at the highest quality level.

Fruit Storage under Modified or
Controlled Atmosphere and Fruit Ripening

For long-term fruit storage, special cold rooms with gas composition modification are available. In particular, the oxygen content is reduced and the content of carbon dioxide (CO2) is increased, which significantly slows down the ripening process. By measuring and specifically changing the gas composition, the specific optimal storage conditions for each type of fruit can be set (CA - controlled atmosphere). A ULO (ultra-low oxygen) storage is defined as a storage facility where very low oxygen levels are set at the lower limit of biological activity.

For some apple varieties, storage periods of up to one year are thereby possible without any noticeable loss of quality. During the ripening of fruit and vegetables, the gaseous plant hormone ethene (C2H4, ethylene) is released. This accelerates the ripening of many fruits, so that it is used to control the ripening of bananas, tomatoes and citrus fruits. The measurement of ethene in the fruit storage or in the ripening chamber can therefore provide information about the ripening state of the fruit.

m-u-t has developed individual, modularized sensor solutions for a renowned fruit storage system manufacturer in " Altes Land" near Hamburg, the largest enclosed fruit cultivation area in Europe. These solutions comprise one module each for the measurement of carbon dioxide (CO2) and oxygen (O2). The module for measuring carbon dioxide is based on the optical NDIR measuring principle and can be configured and calibrated for different maximum concentrations between 5% and 100% CO2.

Online Monitoring of Anesthetic Gas for Work Safety

Nitrous oxide (N2O, "laughing gas") is used for anesthesia during medical operations. Some of the anesthetic gas is emitted into the environment. This is caused by leaks from the anesthesia device or the mask respectively the tube on the patient, and by patients breathing out the absorbed gas after the medical intervention. To protect medical staff from long-term consequences, strict workplace limits must be observed. For continuous monitoring of these threshold values, m-u-t has developed a monitoring system based on optical NDIR measurement for N2O, which draws in ambient air and continuously measures and displays the concentration.

The measured values are evaluated directly in the device, and based on the recommendations of the MAK commission, for example, they are assessed as to whether limit values are exceeded. In this process, permissible, short-term exceedances of the threshold value are also considered and, if necessary, a multi-stage alarm is activated on this basis. For documentation purposes, the measured values are stored over a period of several weeks. By using an attachable probe, it is also possible to search for leaks, e.g. in anesthesia equipment. The device is designed for use in hygienic areas and is disinfectable.

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Different measuring principles can
be used to measure oxygen:

  • An electrochemical, galvanic cell is characterized by low power consumption. The oxygen measuring module can be calibrated for measuring ranges with end values from 10% up to 100% oxygen.
  • An optical oxygen sensor based on fluorescence quenching also has a low power consumption and is available for a measuring range of up to 25% oxygen.
  • Electrochemical oxygen sensors based on a zirconium dioxide oxygen pump cell are as well available for measuring ranges with very low oxygen concentrations. The measuring ranges range from 0.001% to 0.1% up to 1% to 96% oxygen.

For the measurement of ethylene (C2H4) a NDIR based module is available. Here a multi-reflection cell is used to achieve high sensitivity and accuracy in the concentration range up to 2000ppm. As a multigas sensor, this module can also measure CO2 in the low and medium concentration ranges up to 10,000ppm, as well as oxygen using a zirconium dioxide pump cell. Furthermore, sensors for pressure, humidity and temperature are integrated.