Mastering Differential Protection

What you'll learn:
Basic Definition of differential relay
Working principle of differential relay
CT polarity, why it is important
Current notation methodology, dot & cross
CT compared to the current source
Differential relay in the zone and out of zone fault
Through fault
Single Source feed differential protection scheme
Double Source feed differential protection scheme
Considering internal and external fault on double feed system
Pick Up value of a differential relay
Max stabilizing current
Stabilizing factor
Through fault stability
The actual behavior of CT
Ratio and phase error of CT
Biased Differential protection
Circulating current & spill current
Slope of differential Relay
Restaining and operating coils
Restaining and operating current
Comparison of stability between simple and biased differential relay
Variable pickup value for biased differential protection
Calculation of slope for internal fault
Calculation of slope for external fault
The operating point of the relay
Single Phase Earth Leakage Relay Three Phase Earth Leakage Relay
Three Phase Earth Leakage Relay

Requirements
Basics of electrical engineering

Description
Hi,

The relays used in power system protection are of different types. Among them, differential relay is a very commonly used relay for protecting transformers and generators from localized faults.

The differential relay is one that operates when there is a difference between two or more similar electrical quantities exceeds a predetermined value. In the differential relay scheme circuit, there are two currents come from two parts of an electrical power circuit. These two currents meet at a junction point where a relay coil is connected. According to Kirchhoff Current Law, the resultant current flowing through the relay coil is nothing but the summation of two currents, coming from two different parts of the electrical power circuit. If the polarity and amplitude of both the currents are so adjusted that the phasor sum of these two currents, is zero at normal operating condition. Thereby there will be no current flowing through the relay coil at normal operating conditions. But due to any abnormality in the power circuit, if this balance is broken, that means the phasor sum of these two currents no longer remains zero and there will be non-zero current flowing through the relay coil thereby relay being operated.

I have covered the following topics in this course,

Basic Definition of differential relay

Working principle of differential relay

CT polarity, why it is important

Current notation methodology, dot & cross

CT compared to the current source

Differential relay in the zone and out of zone fault

Through fault

Single Source feed differential protection scheme

Double Source feed differential protection scheme

Considering internal and external fault on the double feed system

Pick Up value of a differential relay

Max stabilizing current

Stabilizing factor

Through fault stability

The actual behavior of CT

Ratio and phase error of CT

Biased Differential protection

Circulating current & spill current

Slope of differential Relay

Restaining and operating coils

Restaining and operating current

Comparison of stability between simple and biased differential relay

Variable pickup value for biased differential protection

Calculation of slope for internal fault

Calculation of slope for external fault

The operating point of the relay

Single Phase Earth Leakage Relay

Three Phase Earth Leakage Relay

Thanks

Muhammad Kashif

Who this course is for
Students, professionals