For voltages higher than about 300 to 500 kV, the cascading of transformers is a big advantage, as the weight of a whole testing set can be subdivided into single units and therefore transport and erection becomes easier. Also, with this, the transformer cost for a given voltage may be reduced, since cascaded units need […]
GENERATION OF AC HIGH VOLTAGE BY CASCADED TRANSFORMERS Read More »
For voltages higher than 400 KV, it is desired to cascade two or more transformers depending upon the voltage requirements. With this, the weight of the whole unit is subdivided into single units and, therefore, transport and erection becomes easier. Also, with this, the transformer cost for a given voltage may be reduced, since cascaded
CASCADED TRANSFORMERS METHOD FOR GENERATING AC HIGH VOLTAGE Read More »
Voltage sags may cause lamps to extinguish. Light bulbs will just twinkle; that will likely not be considered to be a serious effect. High pressure lamps may extinguish; it takes several minutes for them to re-ignite. All lamps, except incandescent lamps, require high voltage across the lamp electrodes during starting. This voltage is essential to
EFFECTS OF VOLTAGE SAGS ON LIGHTING LOADS Read More »
A rotating machine is less exposed to lightning surge as compared to transformers. Because of the limited space available, the insulation on the windings of rotating machines is kept to a minimum. The main difference between the winding of rotating machine and transformer is that in case of rotating machines the turns are fewer but
SURGE PROTECTION OF ROTATING MACHINE Read More »
It has been observed that in case of very small gaps of less than a mm and the gas pressure between the gap lies in the range 10–9 to 10–2 torr, there is no change in the breakdown voltage i.e, if the gap length is small a variation of gas pressure in the range given above doesn’t affect the breakdown voltage.
EFFECT OF PRESSURE ON BREAKDOWN VOLTAGE IN VACUUM Read More »
The vacuum breakdown mechanism based on this theory makes following assumption: (i) A loosely bound particle known as clump exists on one of the electrode surfaces. (ii) When a high voltage is applied between the two electrodes, this clump gets charged and subsequently gets detached from the mother electrode and is attracted by the other
The main requirements of the insulating materials used for power apparatus are: 1. High insulation resistance 2. High dielectric strength 3. Good mechanical properties i.e tenacity and elasticity 4. It should not be affected by chemicals around it 5. It should be non-hygroscopic because the dielectric strength of any material goes very much down with
SOLID DIELECTRICS USED IN POWER APPARATUS Read More »
GROUNDING Grounding is one of the most important aspects of an electrical distribution system but often the least understood. Your Electrical Code sets out the legal requirements in your jurisdiction for safety standards in electrical installations. For instance, the Code may specify requirements in the following areas: (a) The protection of life from the danger
GROUNDING AND BONDING Read More »
1) OLD GUIDELINES ARE NOT THE BEST GUIDELINES Guidelines like the Computer Business Equipment Manufacturers Association Curve (CBEMA, now called the ITIC Curve) and the Federal Information Processing Standards Pub94 (FIPS Pub94) are still frequently cited as being modern power quality guidelines. The ITIC curve is a generic guideline for characterizing how electronic loads typically
TOP 5 POWER QUALITY MYTHS Read More »
The three major factors contributing to the problems associated with power quality are: USE OF SENSITIVE ELECTRONIC LOADS The electric utility system is designed to provide reliable, efficient, bulk power that is suitable for the very large majority of electrical equipment. However, devices like computers and digital controllers have been widely adopted by electrical end-users.
MAJOR FACTORS CONTRIBUTING TO POWER QUALITY ISSUES Read More »