METHOD FOR DETERMINATION OF ELECTROMOTIVE FORCE AT ALTERNATING VOLTAGE AND CIRCUIT RESISTANCE Russian patent published in 2014 - IPC G01R27/08 

FIELD: electricity.

SUBSTANCE: invention is referred to mining engineering and it can be used in mine working to ensure electrical safety during operations, prevention of gas explosions, mine fires and related sequences. The facility is selected; the circuit is mounted in it and electricity is supplied. Preset values of voltage, current strength, temperature, circuit resistance are measured and possible limit deviations are defined for the preset values. When deviations are present respective values of voltage and resistance are measured by instrumentation; simultaneously voltage, current strength, resistance, temperature, time are measured within the whole period of measurements. Curve of electromotive force (EMF) versus voltage and resistance simultaneous change, i.e. volt-ohm-ampere curve (VOAC) for the circuit is plotted. At VOAC sections condition type is determined for current strength dependence on voltage and resistance - positive dependence on voltage and negative dependence on resistance or negative dependence on voltage and positive dependence on resistance. Since then values of voltage, resistances are measured simultaneously and mode of mode change and initial EMF value are defined at each condition and for each section. Then the first condition, second ratio of mode parameter changes for circuit voltage and resistance are considered and EMF is defined in the circuit at alternating voltage, alternating resistance and different modes of their changes for each VOAC section as per mathematic formulae. Hereupon incremental EMF value is measured for each VOAC section, incremental values are summed up and total EMF value in the circuit is defined for the whole period of measurements.

EFFECT: improving accuracy of EMF determination, reliability of supplied current value and optimisation of cost-performance ratio of mining plants operation.

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