Elimination of the methodological error in measuring linear parameters of electrical cables for intrinsically safe systems

The necessity of monitoring the linear electrical parameters of cables for intrinsically safe applications is described and it is indicated that the manufacturer or supplier of cables must ensure that the cable parameters comply with current standards. The problem of unproductive consumption of cable products during its control is considered. It is noted that standard measurement methods for such a linear parameter as inductance are correct when using cable samples, the length of which is much shorter than the construction lengths. An analytical model of a cable line as an electrical facility with distributed parameters is investigated. The reason for the introduction of a limit on the length of the cable is shown, caused by the transition from a complete to a simplified model traditionally used in some standards.A systematic method for measuring the linear parameters of cables is proposed, based on an unconventional – reverse – solution, which consists in switching from the measured secondary parameters to the calculation of primary parameters. In this case, the secondary parameters are measured in accordance with the well – known standardized idling – short circuit method. The proposed method is practically free from the limitation of the length of cable samples. This allows you to control all finished cable products without cutting off samples for measurements. The measurement error does not exceed the limit set by the standards equal to 1 %. The results obtained provide non-destructive testing during acceptance tests of cable products intended for intrinsically safe systems.