Doble (Norway)

Abstract

Sudden changes in the power system, such as faults, network changes due to line trip outs, and disconnection of large loads or a generating plant, causing oscillations until remaining generators adjust and settle to new stable conditions. In some cases these power oscillations or swings are so large that some generators run out of step and lose synchronism. With generators having different frequencies these power swings result in voltages and currents in different parts of the networks to swing in amplitude and phase angle. The impedance measurements based on these varying voltages and currents will also oscillate. If the measured impedance becomes very small and enters the distance relay zones it can lead to an undesired trip of the distance relay. Distance relays have power swing blocking features to detect these conditions and prevent a misoperation for stable power swings. However, during the blocking period a fault can occur on the line and the distance relay must detect this condition and unblock the distance zones.

En este trabajo se realizó la microencapsulación de un perfume comercial mediante una doble emulsificación, la coraza de poliurea fue sintetizada por la reacción de Lisina con dos diisocianatos comerciales, uno aromático y otro alifático. En la síntesis se evaluó el efecto que tiene la relación molar amina:diisocianato y el tipo de emulsificante. Se optimizó el tamaño de partícula utilizando un diseño factorial 32 y análisis de superficie de respuesta, las variables fueron: cantidad de alcohol polivinílico y la relación de fase dispersa a fase continua. Las microcápsulas se caracterizaron mediante: análisis de calorimetría diferencial de barrido (DSC), espectroscopía infrarroja (IR), microscopía electrónica de barrido (SEM) y tamaño medio de partícula. La doble emulsificación permite un mayor rendimiento de encapsulación del perfume, las micropartículas presentan un menor tamaño de partícula cuando: se emplea diisocianato aromático, un aumento de coloide protector (PVA) y una disminución de la fase dispersa.

The deployment of radio frequency interference (RFI) measurement has gained increasing acceptance as a front line, non-invasive technique to assess the condition of individual high-voltage (HV) electrical equipment items as part of a substation surveillance program. However, successful detection and discrimination of low-repetition rate discharges that typically accompany electrical deterioration is constrained by the capabilities and limitations of the field spectrum/RFI analysers used and the electro-magnetic interference (EMI) measurement techniques supported. This paper presents a novel approach to RFI measurement and assessment that is more sensitive to the RFI emissions that typically accompany electrical deterioration and provides more effective discrimination of the discharge phenomena from the ambient frequency spectrum and noise. Case studies from substation surveillance are presented to demonstrate the effectiveness of the approach. The technique is effective with a wide range of HV equipment and is less reliant on expert knowledge for a practicing engineer to confidently characterise and trace electrical deterioration with a high degree of confidence.

In industrial high frequency dielectric heating, heating cycles involving rates of temperature increase up to three hundred or four hundred degrees (F) per minute are common. It is important to know the values of the dielectric properties of the substance heated over the whole range of the heating cycle. Conventional methods of measurement, such as ASTM shunted susceptance, are not available as they all involve the steady state, and such low values of stress that there will be no appreciable loss or rise of temperature during the measurement.