Power Systems
Anti pumping relay is used in the circuit breakers to prevent unwanted closing of the breaker after immediate tripping. Due to failure of the TNC switch (Trip normal close) or any other discrepancy in the CB closing circuit, continuous CB close command can be extended to the closing coil. In that condition, after tripping the…
The trip circuit supervision relay always monitors the healthiness of the trip circuit including a connected trip coil of the CB. Tripping or isolation of CB is the most important part of power system protection. Always 02 nos. trip circuits are used in the CB for system redundancy. Due to the failure of the trip…
Grading capacitor is commonly used in High Voltage Circuit Breaker for uniform voltage distribution across the Breaker contacts at CB open position. In a multi-break Circuit Breaker, Grading capacitors are connected in parallel with every break of the CB. Reasons for using Grading Capacitors in Circuit Breakers. When the capacitors are connected across the breaks…
In addition to the general protection, backup impedance protection or distance protection is also used in Generator, Transformer & Reactor to protect during external faults in the power system. Generally, impedance protection is most commonly used for the protection of transmission lines. When the Impedance value goes below the set value during the fault or…
The main difference between earthing and grounding is that – Under Earthing, the circuit is physically connected to the ground to flow circulating current or fault current of the circuit to the protection of the system, Under Grounding, the circuit is physically connected to the ground to discharge the electrical energy to earth for protecting…
Floating neutral is a condition, in which the neutral wire of any circuit is disconnected from the ground. In AC system, the neutral wire is permanently grounded to the earth. However, floating neutral may occur in a power system due to loose connection, braking of neutral flat, wrong circuit connection, or due to short circuit….
OLTC stands for On-load tap changer which is used in Transformer to regulate the output voltage. OLTC is installed inside the transformer main tank. It is operated by a Drive mechanism which is connected to OLTC through a tie rod. Generally, the Drive mechanism is mounted on the outside body of the Transformer. Based on…
When the voltage goes higher than the rated voltage is called Over Voltage. It is a very common issue in Power systems. System voltage is to be maintained as per the designed voltage for the stability of the power system. All the equipment and insulators used in substations and transmission lines are designed for a…
After opening the Circuit Breaker under load or fault condition, a transit voltage appears across the breaker contacts which is called Restriking Voltage. Frequency of Restriking voltage goes in kH. During arcing period, transient voltage appears across the contacts at or near current zero. If dielectric medium between the CB contacts is greater than the…
The Corona Effect is the phenomenon of electric discharge in high voltage transmission lines and substations. Hissing noise and violet glow were observed under the corona effect. Power loss, damage to high voltage electrical components, and noise are observed due to corona discharge in the Transmission line. Why does corona effect in transmission line? Due…
