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• ALGORITHM FOR TEMPERATURE CORRECTION OF VIBRATION DENSITY METERS

  O.V. Zatserklyanyi

  2021-02-13

  Abstract ▼

  In this article additional temperature error of vibration density meters in liquids and gases
  is reviewed. Particularly scrutinized are the effects of change in the temperature of the medium
  on the vibration frequency of the density vibration transducers. Main principle of operation
  and advantages of vibration density meters is described. The article analyzes and describes the
  existing algorithms of calculating density and active temperature compensation as well as the
  disadvantages of those algorithms. It points out to the significant limitations of temperature
  calibration diapason of the existing methods which relate to the necessity of using distilled water.
  Basing on the previous vibration transducer simulation and on the established main function of the elastic modules of the metal’ temperature properties a new thermal compensation
  algorithm, which does not involve liquid compensators, was introduced. Main advantages of the
  new algorithm are demonstrated. Those advantages emerge due to using vacuum as a medium
  surrounding the vibration transducer. One of the most notable benefits is significant extension
  of the calibrated temperature range. A possibility of applying the algorithm for calibrating density
  meters in extreme temperatures is introduced. Furthermore, formulas for calculatingthe
  value of the oscillation period of the converter which account for temperature changes (thermal
  compensation period) are presented. The advantages of using second order polynomial with
  zero linear term as a calibration function are also provided. Methodology behind conducting
  the experiments, types of equipment and measuring instruments are described in detail. Resul ting
  experimental data for vibration transducers made of three different metals is presented. The
  obtained data is analyzed, which led to a conclusion that application of suggested algorithm of
  thermal compensation of liquid and gases density meters’ vibration transducers is feasible and
  expedient.

• PARAMETRIC MATCHING OF INSULATION MONITORING DEVICES AND DC DISTRIBUTION SYSTEMS

  А. V. Khludenev

  280-289

  2025-07-31

  Abstract ▼

  The aim of the study is to develop a method for parametric matching of insulation monitoring
  devices, unearthed DC distribution systems and discrete inputs of relay protection.
  The use of unearthed DC distribution systems for power supply to relay protection devices
  and other responsible consumers makes it possible to ensure high reliability and safety during their operation. It is necessary to ensure uninterrupted power supply to these consumers
  even in the event of a ground fault in one of the DC distribution network poles. Insulation
  monitoring of the network poles and the prompt execution of repair work when the insulation
  resistance falls below the critical level set by the response value, are a guarantee of high
  reliability of power supply. The article discusses the reasons leading to dangerous levels of
  pole voltage unbalance and false triggering of relay protection discrete inputs during ground
  faults of the signal lines connected to them. A method based on multivariate DC analysis is
  proposed to determine the matched insulation monitoring response value with the DC network
  parameters and discrete inputs parameters, when the conditions for the occurrence of
  such accidents are excluded. The influence of insulation monitoring devices in a DC system
  on pole voltages unbalance and relay protection operation is also considered. A modification
  of the insulation monitoring active method is proposed, which does not create additional pole
  voltage unbalance and risks of relay protection misoperation. The operating range of the
  static characteristics of the pole voltages and leakage current measuring transducers is narrowed
  in the grid unbalanced modes by using a modified active insulation monitoring met hod.
  Estimates of the increase in the insulation resistance measurement error arising in these
  modes are obtained