Voltage Tolerance Of Equipment Research Articles

A Voltage Sag Severity Evaluation Method for the System Side Which Considers the Influence of the Voltage Tolerance Curve and Sag Type

Considering the influence of user equipment voltage tolerance characteristics and sag types on the evaluation results, this paper proposes a voltage sag severity evaluation method for the system side which considers the influence of the voltage tolerance curve and sag type. As such, a quantitative evaluation of the severity of voltage sag events can be achieved. Firstly, the user’s voltage tolerance curve is used to construct the comparison reference value of the energy index, in order to realize the rapid analysis of the severity of the sag event in the normal area and the abnormal area. Secondly, aiming at the problem of insufficient descriptions of the severity difference of sag events in uncertain areas, an improved energy index evaluation model combined with user tolerance characteristics is established through an interval division and interval weight calculation, so as to divide and evaluate the severity of sag events in uncertain areas. Considering the influence of the sag type on the voltage tolerance curve and user equipment, the energy index correction factor is then constructed, and the measurement function is used for an interval evaluation to obtain the ranking result of the voltage sag severity, which is more in line with the actual situation. Finally, the rationality and effectiveness of the proposed method are verified by analyzing 24 voltage sag events at a monitoring node.

Failure Rate Evaluation of Sensitive Equipment Caused by Voltage Sag

In order to accurately evaluate sensitive equipment failure rate caused by voltage sag, the concept of credibility measure is introduced to measure the uncertainty of equipment failure event. This evaluation measure can avoid the deficiencies containing in classical probability measure which needs a large number of testing samples. The uncertainty of failure event is presented by a fuzzy measure where the membership function of equipment voltage tolerance curve corresponding to the characteristic quantities in the uncertain area was determined by fuzzy statistical and a polynomial fit method. Then the credibility distribution function was determined. The proposed evaluation model of sensitive equipment failure rate caused by voltage sag is developed. Using the practical testing samples, the personal computer (PC) was evaluated by the proposed method. Comparing the proposed method with current methods, the results have shown that the proposed method is proper, correct and credible. This method may be more practicable in practical condition.

Credibility Measure and Assessment Method of Equipment Severity to Voltage Sag

In order to accurately describe the equipment’ severity caused by voltage sag, the credibility measure which meets the conditions of non-additive is proposed based on their physical properties of responses. This assessment measure can avoid the deficiencies that classical probability measure needs a large number of samples and the non-duality of fuzzy measure. The membership functions of sensitive equipment voltage tolerance capability that corresponding to the characteristic quantities in the status uncertain area was determined by fuzzy statistical method and polynomial fitting method. Then the joint credibility distribution function was deduced based on uncertainty theory. Hence, the assessment model of severity of equipment failure is constructed. Based on practical samples, the PCs were simulated using the proposed method. Comparing the simulation results with methods using classical probability measure and possibility measure prove that the proposed method is proper and credible and can reflect practical condition more objectively.

Credibility Measure and Its Assessment of Customer Equipment Failure Probability Due to Voltage Sag

In order to accurately describe the equipment’ severity caused by voltage sag, the credibility measure which meets the conditions of non-additive is proposed based on their physical properties of responses. This assessment measure can avoid the deficiencies that classical probability measure needs a large number of samples and the non-duality of fuzzy measure. The membership functions of sensitive equipment voltage tolerance capability that corresponding to the characteristic quantities in the status uncertain area was determined by fuzzy statistical method and polynomial fitting method. Then the joint credibility distribution function was deduced based on uncertainty theory. Hence, the assessment model of severity of equipment failure is constructed. Based on practical samples, the PCs were simulated using the proposed method. Comparing the simulation results with methods using classical probability measure and possibility measure prove that the proposed method is proper and credible and can reflect practical condition more objectively.

Effects of nonsinusoidal supply on voltage tolerance of equipment

This letter shows the effects of harmonics in the voltage supply on the voltage tolerance of equipment. Several laboratory tests have been made to obtain the voltage tolerance curves of a personal computer using a pure sinusoidal voltage supply and under different nonsinuoidal conditions. The analysis shows that the voltage tolerance of the equipment used in the test depends on both the voltage harmonic distortion magnitude and the phase difference between harmonics, with the equipment being more sensitive to low order harmonics. Introduction: Voltage sag is a sudden decrease in the voltage am- plitude followed by a return to the initial level after a short time. Voltage sags are produced by faults in the supply network, both permanent and transitory, rapidly varying loads or equipment taking high current at starting. Voltage sags are important power quality problems to many in- dustrial customers because of the sensitivity of electrical and electronic equipment, such as process controllers, adjustable speed drives, pro- grammable logic controllers, or personal computers to voltage sags. A way to characterize the behavior of equipment to voltage sags is to use voltage-tolerance curves. The first voltage-tolerance curve, the CBEMA curve—which was initially applied to data processing equipment—shows that the sensitivity of equipment is very dependent on the duration of the voltage sag. This voltage-tolerance curve is an important part of IEEE standard 1346 (1). Recently, a revised CBEMA curve has been introduced by the Information Technology Industry Council. This curve, referred to as the ITIC curve, has introduced stricter requirements than the CBEMA curve, because power quality monitoring has shown a large number of voltage sags under the

Effects of Nonsinusoidal Supply on Voltage Tolerance of Equipment

Effects of Nonsinusoidal Supply on Voltage Tolerance of Equipment