TRANSFORMER PROTECTION

 There are different kinds of transformers such as two winding or three winding electrical power transformers, auto transformer, regulating transformers, earthing transformers, rectifier transformers etc. Different transformers demand different schemes of transformer protection depending upon their importance, winding connections, earthing methods and mode of operation etc.It is common practice to provide Buchholz relay protection to all 0.5 MVA and above transformers. While for all small size distribution transformers, only high voltage fuses are used as main protective device. For all larger rated and important distribution transformers, over current protection along with restricted earth fault protection is applied. Differential protection should be provided in the transformers rated above 5 MVA.
 epending upon the normal service condition, nature of transformer faults, degree of sustained over load, scheme of tap changing, and many other factors, the suitable transformer protection schemes are chosen.

Nature of Transformer Faults

Although an electrical power transformer is a static device, but internal stresses arising from abnormal system conditions, must be taken into consideration. A transformer generally suffers from following types of transformer fault-

1. Over current due to overloads and external short circuits,
2. Terminal faults,
3. Winding faults,
4. Incipient fault 

 All the above mentioned transformer faults cause mechanical and thermal stresses inside the transformer winding and its connecting terminals. Thermal stresses lead to overheating which ultimately affect the insulation system of transformer. Deterioration of insulation leads to winding faults. Some time failure of transformer cooling system, leads to overheating of transformer. So the transformer protection schemes are very much required.

The short circuit current of an electrical transformer is normally limited by its reactance and for low reactance, the value of short circuit current may be excessively high. The duration of external short circuits which a transformer can sustain without damage as given in BSS 171:1936.


If you want to learn about switch-gear and Protection, If you want to learn about Electrical and Electronics thing like Automation, Protection, Designing, etc you need to pay attention to my channel.....
In my Previous videos under transformer protection, I had explained about differential and overload protection. In this video I am Explaining about Transformer protection test setup Make by EDAS Technology.
EDAS EDAS-TP1 single phase Transformer Protection simulation setup is a very versatile and useful learning tool for transformer inter turn fault. It provides a complete set up for experiments on single phase transformer and its protection. The complete system consists of a single phase transformer, meters, contractors / relays, CT’s and other necessary accessories for independent study. Necessary fault simulations are provided to simulate the different fault conditions like inter turn fault, differential protection and over load protection.
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Previous video: Transformer protection part 1: https://youtu.be/YWLlUhMIZTs
Transformer protection part 2: https://youtu.be/uDuG9t5EZqE
Transformer protection Part 3: https://youtu.be/srOWZ_XzRIc
Transformer protection Part 4: https://youtu.be/ASpT6ORnfIs

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