The presentation by Mr. Chetan Patil focuses on transformer protection, detailing issues related to differential protection, such as harmonic restraint, restricted earth fault protection, and Buchholz relay operations. It discusses the advantages and challenges of using various protective equipment, particularly in relation to transformer faults and sensitivity. The content emphasizes the need for proper protection mechanisms to ensure the reliability of transformers amidst potential faults.

1. Sharad Institute of Technology College of
Engineering, Yadrav (Ichalkarnji)
A
Presentation On
transformer protection
Presented By,
Mr. Chetan Patil.
Assistant Professor
Department of Electrical Engineering

2. 
 Problems Arising In differential Protection Applied To Transformer.
 Harmonic Restraint And Harmonic Blocking.
 Restricted Earth Fault Protection
 Buchholz Relay
Contents

3. 
 Difference in lengths of pilot wires on either sides of relays.
 Difference in C.T. ratios due to error difference at high values of short
circuit current.
 Magnetizing inrush current.
 Tap changing.
 Saturation of magnetic core.
Problems Arising In differential
Protection Applied To Transformer

4. Harmonic Restraint And Harmonic Blocking
 When transformer is connected
to supply it will take large
current 16 to 10 times full load, to
avoid this difficulty harmonic
restraint relay is used.
This type of relay sensitive to
fault current only it does not
operate due to magnetizing
current.

5. Restricted Earth Fault Protection
 The restricted earth fault
relay does not operate for
earth fault beyond the
protected zone of
transformer.
 Such type of protection
system is not sensitive.
 Such type of system operate
for earth fault current of
about 15% of rated winding
current.

6. Buchholz Relay
 In this type of relay there are
two main circuits are used
 Alarm circuit
 Trip circuit
 The upper element is closes the
alarm circuit during incipient
fault.
 The lower element is used to
trip the CB for the internal
fault.

7. 
 It is simplest form of transformer protection.
 It is used protection against incipient fault.
Advantages

8. 
 It can be only used for the oil immersed transformer.
 It detect only the fault below oil level in the transformer.
 It is only used above 500KVA or 750KVA for the economic
consideration.
Disadvantages

9. 
 There are many problems in transformer such as magnetizing inrush
current, tap changing, saturation of magnetic core , difference in C.T.
ratios etc.
 The protective equipment's such as CB, relays are gives the protection
to the transformer from earth fault, harmonic blocking, incipient fault
and maintain the reliability of transformer.
Conclusion

10. 
Thank You

11. 
 Power system protection & Switchgear: B.Ram &
B.N. Vishwakarma.
 Switchgear & Protection: Sunil S.Rao, Khanna
Publications.
References