It is often overlooked by us that whether sealed Transformer oil drums are stored in horizontal or in vertical positions. But, there is difference, especially when stored outside because of a phenomenon called ‘Breathing of Barrel’. Every sealed Transformer oil drum breathes in and breathes out due to variations in the ambient temperature conditions. Even though oil drum is completely sealed, during hot days the oil drum gets heated and the oil in the drum expands and pushes the air accumulated over the oil to its surroundings. When temperatures are cooled, the oil in the drum contracts and creates partial vacuum in the drum and sucks outside moisture mixed air into the drum. This breathing in and breathing out of oil drums happens even they are not opened once.
When oil barrels are stored vertically outside during rainy season, rain water settles on the top of the barrel with its bung submerged. During breathing in of the oil barrels, the water is sucked into the drum. Once, the water enters the drum, it gradually settles at the bottom and raises the oil level in the drum. As this process continues, more and more water settles at the bottom and deteriorates oil and sometimes deforms the shape of the drum also.
To avoid this, the following advices may be noted while storing transformer oil barrels.
As far as possible Transformer oil drums should not be stored outside.
Transformer oil barrel is to be stored in horizontal position so that; there is no accumulation of water on top of the drum during rainy season.
Transformer oil barrel is to be stored in horizontal position with its bungs in 3 O’clock and 9 O’clock positions, so that positive pressure is maintained at bungs as the oil level in the drum will be above the bungs in this position. This prevents breathing of drum there by entering of moisture and dirt from surroundings into the drum can also be avoided.
Oil drums are to be stored horizontally on good platform and covered.
First in and First out method should be followed.
As far as possible Transformer oil drums should be stored in clean, cool and dry places.
Oil surge relay (OSR) is a single float Buchholtz relay fixed to OLTC and its conservator tank. The purpose of OSR is similar to the Buchholtz relay and acts whenever sudden oil rush towards OLTC conservator tank happens due to flashover in OLTC tank. Generally, Buchholtz relay connected to the main tank contains two floats i.e. upper and lower, electrically connected to alarm and trip circuits. Apart from low oil level condition, upper float acts when gasses accumulate due to minor internal faults in the Transformer and lower float acts when sudden rush in oil towards to conservator tank is sensed due to major internal faults in the Transformer. In the OSR connected to OLTC, only single float is provided which acts due to oil rush caused from OLTC internal fault. If the upper float, which acts due to accumulation of gasses, is also provided in the OSR, many times gasses that are normally generated in the frequent operation of OLTC trips the Transformer without any internal fault. Hence only single float is provided in the OSR connected to OLTC to avoid unwanted interruption of supply to the Transformer and ensures safety tripping when any internal fault occurs or low oil level condition in the OLTC tank.
The silica gel breather cup of a Transformer is partially filled with oil to avoid entering of moisture into the Transformer. Every Transformer breathes in and out because they are filled with oil and tightly sealed with gaskets. As the oil expands due to rise in temperature, the pressure builds up , consequently, the vapour and dry air accumulated in the conservator are breathed out. During the fall of temperature, oil in the Transformer contracts and creates partial vacuum in the tank which makes the Transformer to breathe in air from the outside. In the process of breathing in outside air, moisture and dust particles in the outside air are also sucked in. But, the oil in the breather cup obstructs dust particles and settles them at its bottom. The moisture entered is absorbed by the silica gel in the breather.
The oil in the breather cup is only partially filled up to the mark given on the cup. If oil in the cup is over filled, while brething in, the oil gets into contact and absorbed by the silica gel resulting in bottom portion of silica gel is permanently wasted as the oil absorbed silica gel cannot be reactivated again.
If you observe any substation, the ground of the substation yard is filled with crushed gravel stones. This is because of the following reasons pertain to safety from shock.
1) Although substation grounding is chosen to provide low resistance path, the entire ground is filled with crushed stones to provide a high resistance layer so that it can act as an insulation between our foot and the ground.
2) The stone layer on the substation ground provide high resistance so that the fault currents flow into the ground but not along the ground.
3) To minimise step potential and touch potential voltages.
4) It avoids pool of inflammable oil etc. on the substation ground in case of any spilling of insulation oil from the equipment. This also avoids spreading of fire from one equipment to the other in the substation.
5) The rocky outer layer slows down the evaporation of moisture in the earth’s upper layers.
6) It restricts entering of snakes and other reptiles as the surface would be inconvenient to crawl.
7) It avoids growth of plants and weeds in the substation yard to some extent.
8) Generally 20 to 25mm baby gravel stones are used instead big size stones to facilitate movement of persons and equipment in the substation yard.
Lord Shiva is one of the prominent and most worshipped God in Hinduism. Basically, Hinduism described the existence of the universe with three main philosophies : 1) Brahma, the symbolism for creation, 2) Vishnu, the symbolism for sustaining force of the universe and 3) Shiva, the symbolism for destruction. One of the most interesting feature of Hinduism lies in worshipping even the destructor , Lord Shiva !!! The philosophy behind the depiction of Shiva runs around ‘death’ , the final result of destruction and burial ground is where he lives in. Lord Shiva is portrayed in every picture with symbols of destruction or ‘death causing elements’ in the world like fire (in third eye), snake ( around neck), Trishul ( a weapon in hand), whirling water (on his head), poison ( in the neck) and a demon (under his feet) etc. Apart from these elements, Shiva is also portrayed with musical features like ‘Dhamarukam’ in one hand with musical performers around him and a dancing posture (NATRAJ) and his dance is very popularly known as ‘Shiva Thandavam’ with a perfect rhythm.
Paperless Office is a concept, which I am very attracted to; where in every document in the office is in digital format and paper is eliminated or greatly reduced. In general, in the developing countries like India, every office will have lot of paper work involved and especially in Government offices. Today we are in the age of computerisation and rapid communication techniques have been developed in the recent past. We can send the information in digital format to the other side of the globe within seconds. Still, we use lot of paper in our offices. In this article we shall see the benefits and possibilities of paperless office.
Rotation and Revolution of the Earth are well known movements of the Earth which we study from our school days. Apart from these, there is another slow and continuous movement of the earth which is called ‘The precession of rotational axis of the Earth’. Earth revolves round the Sun and rotates around itself on an axis which is inclined about 23.40 away from the perpendicular of its orbital plane. Any movement of celestial body is always influenced by the gravitational force existing on the body because of its neighbouring massive objects in the space. So also, the planet Earth is strongly influenced by the gravity of the Sun and the Moon apart from less influencing gravitational forces by the other planets and debris of our solar system. This gravity of the Sun and Moon is the basic responsible factors for the movement of the Earth. Not only the mass of objects but also their distance and orientation with reference to the Earth also causes variations in gravitational force and there by variations in movements of the Earth. Further, our Earth is not in perfect spherical shape but it is bulged at the equator and flattened at poles due to centrifugal forces from its rotation. Rotation causes a distortion from its spherical shape due to envelope of ocean fluids and we see a bulge in the ocean envelopes around the earth. Sea level at the equator is 21 KM higher than the seal level at poles, the distances measured from the centre of the Earth. The gravitational pull of the Sun and Moon on the gyroscopic Earth bulge produces torque on its rotational axis causing it to drift periodically from East to West completing a turn in 25,800 years. This movement of Earth’s rotational axis is called the Precession.
Dreaming is one of the wonderful phenomenon that we experience in our sleep. Dreams have fascinated many artists, philosophers, scientists and even kings. We experience world around us through our sensory organs and the experiencing faculty is our mind. Our mind experiences emotions while we are in wake up state and construct dreams while we are sleeping. In olden days, dreams are often considered as prophesy, divine call, interaction of evil spirits etc. and it is no surprise that even great kings believed that there is a message hidden in their dreams to interpret and act accordingly. A dream is a complex cognitive phenomenon and how humans adopted this interesting feature in the course of evolution is still remained as a mystery.
Water is undoubtedly the essential and basis for life to exist on the planet earth. Water exists abundantly in all three states i.e. solid, liquid and gaseous states on the earth. We human beings are closely associated with water in everyday life. On the average, humans consume 2.5 litres of water each day, although it varies depending on age, gender, climate etc. The percentage of water in human body also varies according to age and gender. The average adult male has about 60 % water and adult woman has about 55% water, because women naturally have more fatty tissue than men and fatty tissue contains less water than lean tissue. The percentage of water in infants is much higher, typically around 75-80 %, dropping to 65 % by one year of age. People feel thirsty when they lose around 2-3 % of their body water. As water in the body is lost, mental performance and physical coordination start to become impaired and no human being can live without water for more than 3-5 days. Now a days, people has got more awareness on the health benefits of drinking pure water. People who are above poverty line are preferring to drink purified water than normal tap water. In this article, I discuss about the water we drink in different forms in our daily routine life to quench our thirst.
It is a common misconception that cell phone usage causes cancer. The cell phone signals are basically electromagnetic signals and mobile phones are low-powered radiofrequency transmitters, operating at frequencies between 450 and 2700 MHz with peak powers in the range of 0.1 to 2 watts. The well-known electromagnetic spectrum is shown below for reference.