Short-circuit effects

In most applications, a bar primary CT is generally used and a normal CT may be suitable. But for too small ratings, where the use of a wound primary CT is imperative, short-circuit effects must be considered, except the CTs for an LT system, where the fault level for such small ratings may be very low and may not matter (Section 13.4.1(5)). For applications on an HT system, where a wound primary CT is imperative, choice of a CT from standard wound primary CTs may still be possible, meeting the minimum requirements of class of accuracy, VA burden and short-time rating. lEC 60044-1 indicates for measuring and protection CTs the maximum short-time factors (STF) that can be obtained economically for a normal wound primary CT where... 

Introduction Types of metal-enclosed bus systems Design parameters and service conditions for a metal enclosed bus system Short-circuit effects Service conditions Other design considerations Skin effect Proximity effect Sample calculation for designing a 2500 A non-isolaled phase aluminium busbar systern... 

In a horizontal vessel, the cross-sectional area of the flow for the upward velocity of the oil is a function of the vessel diameter and the length of the coalescing section. For a vertical treater, the height of the coalescing section does not enter the equation. For larger diameter, vertical-flow treaters (i.e., such as gun barrels) a correction factor for short-circuiting effects must be included in the equation. 

In actual practice continuous agitation is seldom attempted in a single tank, but a series of three, four or even more, smaller agitators used in order to minimize the short circuiting effect. The number of tanks necessary depends primarily on the period of detention necessary. Several articles have been published in which an attempt has been made to derive a mathematical relation between the time of contact, number of agitators necessary and percentage of extraction. 

Tests carried out on a Sn02 sensor covered with a thin platinum film show that this material must be used in great quantities to be fully efficient on the catalytic plan. Beyond 10 nm, we notice noxious short-circuit effects at the level of the information capture. Below 10 nm, the catalytic performance ceases to be satisfying. 

Ceramizable (ceramifiable) silicone rubber-based composites are fire resistant materials developed especially for cable covers application. In case of fire, electrical installations are endangered of short circuit effect which can deactivate lots of important devices, like fire sprinklers, elevators, fire alarms or lamps indicating route to emergency exits. Ceramizable composites are able to sustain functioning of electric circuit on fire and high temperature up to 120 min by producing ceramic, porous layer protecting copper wire inside a cable. 

This fliermal short circuiting effect can be easily detected by simply removing the foam plug, when the system will have a lower boil-off rate ... 

The simulation results were in good agreement with the experimental data. It was found that the heat transfer to the catalyst-packed bed played an important role, especially for endothermic dehydrogenation with a large amount of heat. The clearance between the membrane tube and the protector was found to decrease the conversion of cyclohexane because of the short-circuiting effect, suggesting that one should introduce a different type of protector or a kind of catalyst block to minimize the clearance. 

The rotor is squirrel cage with short-circuited copper rings at the ends. Here also, to vary the starting characteristics of the motor, the skin effect is used by providing deep bars, flat bars, tapered bars or other types of slots (discussed in Section 2.3). 

Before creating a fault condition, to obtain the required /sc the impedance of the test circuit is adjusted so that the required fault current is obtained in all the phases on creating a short-circuit. To provide the required thermal effect (/sc /). the duration of test, /, is then adjusted accor-dingly. The relevant standards therefore stipulate that the test current may be higher or lower than required and can be compensated by adjusting its duration, i. 

Rated short-time current rating this is the same as for the system to which it is connected, and as assigned to the associated switchgear (Section 13.4.1(5)). The effects of a short-circuit on an electrical system are discussed below. 

Assume the temperature of the busbars at the time of fault = 85°C and rectangular flats of electrolytic grade E-91E or its equivalent. Busbars chosen for each phase - four (152.4 mm X 6.35 mm) - which are more than the minimum size required to account for the thermal effects during a short circuit condition... 

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