What is OTI and WTI in transformer?
They are commonly referred to in the industry as Oil Temperature Indicators (OTI) and Winding Temperature Indicators (WTI). Electrical utilities often utilize oil and winding temperature indicators to provide alarm and control signals that are used to activate cooling control systems on a transformer.
How does OTI and WTI work?
The WTI means winding temperature Indicator and OTI means Oil Temperature Indicator which indicates the winding temperature & oil temperature of the transformer and operates the alarm, trip, and cooler control contacts. This instrument operates on the principle of thermal imaging and it is not an actual measurement.
Why are transformers oil cooled?
Oil cooled transformers are used in outdoor installations due to the possibility of oil leakage and spills which pose a fire risk, but these units are more environmentally friendly.
Which of the following cooling methods is used for very large size transformers?
Oil Natural Air Forced (ONAF) In this method, fans are mounted near the radiator and may be provided with an automatic starting arrangement, which turns on when temperature increases beyond certain value. This transformer cooling method is generally used for large transformers upto about 60 MVA.
What is Oltc in transformer?
On-load tap changer (OLTC), also known as On-circuit tap changer (OCTC), is a tap changer in applications where a supply interruption during a tap change is unacceptable, the transformer is often fitted with a more expensive and complex on load tap changing mechanism.
What is the function of MOG in transformer?
A Magnetic Oil level Guage (MOG) is a device used to indicate the position of transformer insulating oil level in conservator of a transformer.
What is WTI CT in transformer?
The WTI, Winding Temperature Indication, Current Transformer are used in Oil Cooled Transformers to monitor the Transformer Winding Temperature to activate High Temperature Alarms, Circuit Breakers and coolers. Designed and manufactured for your specific requirement.
What is Oti transformer?
Oil Temperature Indicator or OTI This device is used to measure the top oil temperature. An oil temperature indicator or OTI is also used for protection of transformer.
What are the advantages of oil as a cooling medium in transformers over the air?
Transformer oil is used as a cooling medium for oil-immersed transformer, and the heat generated by transformer operation is transmitted from transformer oil to metal shell and emitted. It has the advantages of fast heat dissipation, uniform conduction and recoverable insulation performance of the oil.
How many types of cooling transformers are there?
Basically, there are two types of transformer one is the dry type, and another one is oil-immersed type. For the cooling of transformers, the following cooling methods listed below are used.
Why cooling is necessary for transformers discuss air Natural An and oil natural air forced ONAF cooling methods?
By Air Natural method the generated heat in the transformer is cooled by the circulation of natural air. When the temperature of the transformer becomes higher as compared to the temperature of the surrounding air, thus by the process of natural convection, heated air is replaced by the cool air.
What is de energized tap changer?
A de energized tap changer is a switch, which is connected to the winding taps of the transformer. When the tap changer is moved from one position to another, the amount of the tap winding connected into the circuit is changed.
How to cool an oil immersed transformer?
Oil immersed type transformer is cooled by the oil air cooling method and oil water cooling method. Oil Natural Air Natural (ONAN) Natural convection process is used for this type of cooling. The assembly of the core and windings are placed in the oil immersed tank.
What is an oil natural air natural cooling transformer?
As the transformer cooling occurs through the natural processes of conduction, convection, and radiation through the oil means, it is called the Oil Natural Air Natural type of cooling. It is mostly useful for transformers with capacities ranging up to 20MVA.
What are the disadvantages of transformer oil cooling?
The transformer oil can get contaminated creating a problem for cooling. In this type of cooling, the oil is cooled by the air blast with fans. High and less number of fans are automatically switched on and off based on the loads. When there are lesser loads, the cooling will be similar to that of ONAN.
What are the different types of transformer cooling?
Basically, there are two types of transformer one is the dry type and another one is oil immersed type. For the cooling of transformers, the following cooling methods listed below are used. Air Natural. Air Blast or forced. Oil Natural Air Natural. Oil Natural Air Forced. Oil Forced Air Forced.