Power Supply System and Transformers Quiz

<p>From alternating phases in rotation (D)</p> Signup and view all the answers

<p>To switch the supply ON or OFF without opening on fault (A)</p> Signup and view all the answers

<p>Act as protection against overloads and faults (C)</p> Signup and view all the answers

<p>By bridging the neutral section through interruptors (A)</p> Signup and view all the answers

<p>To protect the OHE from flasover caused by the pantograph. (A)</p> Signup and view all the answers

<p>When a neutral section is present in front of the TSS. (B)</p> Signup and view all the answers

<p>0.5 sec to 30 sec (C)</p> Signup and view all the answers

<p>Delta I relay (A)</p> Signup and view all the answers

<p>Instantaneous acting undervoltage relay (D)</p> Signup and view all the answers

<p>It facilitates automatic reclosing after a pre-set time delay. (B)</p> Signup and view all the answers

<p>Failure of a traction sub-station. (A)</p> Signup and view all the answers

<p>Tripping of 25kV Feeder Breaker caused by Mho relay. (D)</p> Signup and view all the answers

<p>By minimizing the continuity of arcs during locomotive operations. (B)</p> Signup and view all the answers

<p>Remote Control Equipment. (A)</p> Signup and view all the answers

<p>Formation of an arc at the overlap. (A)</p> Signup and view all the answers

<p>To prevent service disruptions and maintain infrastructure integrity. (C)</p> Signup and view all the answers

<p>They provide a secondary power source from a nearby sub-station. (B)</p> Signup and view all the answers

<p>Automatic restoration of power after a fault. (B)</p> Signup and view all the answers

<p>0.70 ohm/km (A)</p> Signup and view all the answers

<p>IS:8686 - 1977 (D)</p> Signup and view all the answers

<p>Winding temperature indicator alarm (B), Buchholz alarm (C), Low oil level alarm (D)</p> Signup and view all the answers

<p>To enable secondary injection tests (B)</p> Signup and view all the answers

<p>Hand reset contact in auxiliary relays (A)</p> Signup and view all the answers

<p>0.24 ohm/km (C)</p> Signup and view all the answers

<p>Buchholz alarm and trip (C)</p> Signup and view all the answers

<p>0.43 ohm/km (D)</p> Signup and view all the answers

<p>All protective relays and associated auxiliary relays (B)</p> Signup and view all the answers

<p>Dull black enamel (A)</p> Signup and view all the answers

<p>5A (D)</p> Signup and view all the answers

<p>20% for 8 hours (D)</p> Signup and view all the answers

<p>110 V dc (D)</p> Signup and view all the answers

<p>20% (D)</p> Signup and view all the answers

<p>Silver plated (D)</p> Signup and view all the answers

<p>DDT-12 (C)</p> Signup and view all the answers

<p>Separate earthing terminal (A)</p> Signup and view all the answers

<p>20 VA (A)</p> Signup and view all the answers

<p>80-320% of 5A (A)</p> Signup and view all the answers

<p>Class 2 (C)</p> Signup and view all the answers

<p>10 ms (C)</p> Signup and view all the answers

<p>Harmonic restraining feature (D)</p> Signup and view all the answers

<p>20% to 80% (D)</p> Signup and view all the answers

<p>Maximum through fault current (B)</p> Signup and view all the answers

<p>20% (D)</p> Signup and view all the answers

<p>To step down the voltage from higher levels to 25KV for traction (C)</p> Signup and view all the answers

<p>The feeder circuit breaker clears the fault (C)</p> Signup and view all the answers

<p>By solidly earthing it to the running track rail (C)</p> Signup and view all the answers

<p>To facilitate maintenance without power interruption (B)</p> Signup and view all the answers

<p>It provides additional safety against equipment failure (C)</p> Signup and view all the answers

<p>Interruptors that close on fault but do not open (D)</p> Signup and view all the answers

<p>By bridging the neutral section using interruptors (C)</p> Signup and view all the answers

<p>It reduces inductive interference in adjacent telecommunications circuits. (C)</p> Signup and view all the answers

<p>Differential relays and instantaneous earth leakage relays. (B)</p> Signup and view all the answers

<p>0.15 ohm (D)</p> Signup and view all the answers

<p>Admittance type relay. (C)</p> Signup and view all the answers

<p>2.66 km (A)</p> Signup and view all the answers

<p>Voltage surge protection relay. (A)</p> Signup and view all the answers

<p>100 KVA (C)</p> Signup and view all the answers

<p>It includes an instantaneous overcurrent element. (D)</p> Signup and view all the answers

<p>To ensure adequate traction current flow through the return conductor. (B)</p> Signup and view all the answers

<p>0.70 ohm/km (D)</p> Signup and view all the answers

<p>IS:3231 - 1965 (B)</p> Signup and view all the answers

<p>All alarms of self-reset type (C)</p> Signup and view all the answers

<p>Dull black enamel finish (A)</p> Signup and view all the answers

<p>When the sub-station is unattended (D)</p> Signup and view all the answers

<p>0.24 ohm/km (C)</p> Signup and view all the answers

<p>Is to have hand-reset contact provided when necessary (B)</p> Signup and view all the answers

<p>Flag type operation indicators (D)</p> Signup and view all the answers

<p>0.43 ohm/km (B)</p> Signup and view all the answers

<p>Test plug or separate test blocks (D)</p> Signup and view all the answers

<p>Wrong phase coupling protection (D)</p> Signup and view all the answers

<p>100-800% (B)</p> Signup and view all the answers

<p>VAA-121 (B)</p> Signup and view all the answers

<p>Trip signal processing and distribution (D)</p> Signup and view all the answers

<p>VAA-11 (B)</p> Signup and view all the answers

<p>Overcurrent protection (D)</p> Signup and view all the answers

<p>11% (C)</p> Signup and view all the answers

<p>VAT-11 (B)</p> Signup and view all the answers

<p>VAA-11 (A)</p> Signup and view all the answers

<p>Sensitive single-pole differential relays (D)</p> Signup and view all the answers

Power for traction systems comes from a grid network (132KV, 110KV, or 66KV) either at the substation or a central point. 25KV power is derived from transformers.

Transformers convert high voltage (132/110/66KV) to 25KV for traction; the primary winding is connected to two phases of the incoming three-phase supply, and the 25KV secondary is connected to the overhead lines.

Each 25KV transformer has associated circuit breakers for protection and control. There is an extra feeder breaker for the traction overhead lines.

Substations are fed from different phases of the three-phase system to prevent cascading failures.

These sections are used to isolate parts of the overhead line for maintenance or fault isolation, provided on the overhead line 25KV systems.

The overhead line power is controlled by circuit breakers that do not open on faults (but can be closed). The fault is cleared by the feeder circuit breakers.

In emergencies, adjacent substations can provide power to a shut-down substation by bridging the neutral section.

A system that automatically recloses a 25kV feeder circuit breaker after a predetermined delay following a trip due to an overhead line (OHE) fault.

A temporary fault on the OHE.

A system for tripping circuit breakers at both substations upon detecting a wrong phase coupling (Mho relay) at one substation.

An erroneous connection of phases during a fault, leading to a potential risk of arc generation at the OHE.

A circuit breaker used to switch high-voltage power to traction lines.

A problem affecting the electrical lines that supply power to trains.

Equipment used to operate the inter-tripping of feeder circuit breakers from a distance.

Supplying power from an adjacent substation in case of failure of the current substation.

A relay that detects wrong phase coupling in the electrical system.

The resistance of the overhead line (OHE) when electrical current flows back to the power source through the earth.

The resistance of a single overhead line with earth return is approximately 0.41 ohms per kilometer.

The resistance of two parallel overhead lines with earth return is approximately 0.24 ohms per kilometer.

The resistance of an overhead line, including the effects of resistance and capacitance, is higher than without RC.

A type of relay that can be physically removed from its panel for maintenance or testing.

A relay where the current flows through the back of the relay.

Protective housing for relays, preventing dust from entering and affecting performance.

A tool used to inject test current into the relay for checking its operation.

A relay that automatically resets to its normal state after a fault is cleared.

A relay that requires manual intervention to reset the device after a fault.

A relay that automatically re-closes a circuit breaker after a fault, allowing for a quick recovery of power.

A high-speed relay that trips the corresponding feeder circuit breaker when a fault is detected, initiating a shutdown.

Protects the overhead line (OHE) from flashover caused by a pantograph moving from a live section to an insulated dead section.

Used to detect and clear high resistance earthing faults on the overhead line, which distance protection relays can't detect.

A relay that re-closes the circuit breaker only once after a fault. Subsequent operations require manual or remote control.

The electrical contacts of relays in 25KV traction substations are made of silver-plated material.

Relays in 25KV traction substations are designed to withstand a 20% overload for 8 hours.

Relays in 25KV traction substations are classified as test voltage class 2, according to IS 8686-1977.

Auxiliary relay coils in 25KV traction substations are designed for 110V dc and can tolerate a voltage fluctuation of ±20%.

Relays in 25KV traction substations must be able to operate armature-attracted type auxiliary relays with a burden of over 20VA at 110V dc.

Relays in 25KV traction substations must have nameplates with rating data, serial number, and manufacturer's name.

The metal case of relays in 25KV traction substations must have a separate earthing terminal.

The protection scheme for 25KV traction substations involves various relays and circuit diagrams, ensuring safe and reliable operation.

Indian Railways have historically used electro-mechanical relays manufactured by English Electric (GEC-ALSTHOM) for 25KV traction substations.

Different types of relays are used for transformer protection, including percentage biased differential relays, overcurrent relays, and restricted earth fault relays.

Power for electric trains comes from a high-voltage grid (132KV, 110KV, or 66KV) that's either directly connected or transmitted through the railway's own lines to the traction substation.

Transformers are used to step down the high-voltage power received at the substation (132KV, 110KV, or 66KV) to 25KV, which is the voltage used to power the overhead lines for trains.

Neutral sections are gaps in the overhead line where the electricity is interrupted. They are used for safety during maintenance and fault isolation, creating a safe space to work on the overhead line.

A separate circuit breaker, called the feeder breaker, is used to supply power to the overhead lines. This breaker helps protect from faults by quickly interrupting the electrical flow when problems occur.

Adjacent substations are connected to different phases of the grid's three-phase power system. This ensures that if one substation fails, the other two are likely to remain powered, preventing a catastrophic failure.

In case of a major failure at a substation, power can be supplied to the affected substation by temporarily connecting it to an adjacent one using interrupters to bridge the neutral sections.

Interrupters, used for connecting sections of the OHE, have the unique ability to be closed even during a fault. This allows for swift restoration of power in emergencies despite faults.

The resistance of the overhead line (OHE) when electric current flows back to the power source through the earth.

A transformer installed in series with the 25KV traction overhead equipment to reduce inductive interference in adjacent telecommunication circuits. It forces the traction return current to flow through a dedicated return conductor.

Booster transformers typically have a rating of 100KVA, providing enough capacity to direct the return current.

Booster transformers are typically spaced approximately 2.66 kilometers apart to ensure effective control of the return current.

A relay that compares the currents flowing in the primary and secondary windings of a transformer. If they differ, it indicates a fault within the transformer.

A relay that trips the circuit breaker when the current exceeds a pre-set limit for a specified time. It protects the transformer from overloads.

A relay that trips the circuit breaker when a fault causes current to flow to ground. It protects against electrical shocks and equipment damage.

A relay that trips the corresponding feeder circuit breaker at both substations when a fault is detected. It ensures a quick and synchronized shutdown.

A relay that protects the overhead equipment from faults by measuring the impedance of the line and tripping if the fault is within a specified distance.

Relays designed to operate quickly, within two cycles, for fast fault detection and interruption.

A relay feature that prevents unwanted tripping caused by high frequency currents during transformer energizing.

Allows the relay to be set to trip at different current levels, providing flexibility for various operating conditions.

Provides a sensitivity adjustment for the relay, controlling how much current difference triggers a trip.

Boost the secondary current of bushing CTs to match the relay's rated current, ensuring proper operation at full load.

A device protecting transformers against internal faults like winding short circuits or oil tank leaks. It senses pressure and gas changes in the transformer.

A relay dedicated to protecting the overhead electrical lines that power trains.

A fast-acting relay that trips immediately if the current flow exceeds a predetermined limit.

A relay that constantly monitors the status of the high-voltage circuit breaker on the transformer and alerts if it trips due to a fault.

A relay used to amplify and extend the reach of distance protection relays, which measure the distance of a fault on the overhead line.

A relay that triggers an alarm bell to indicate a fault or abnormal condition.

A relay used in the automation system to control the timing for re-closing the circuit breaker after a fault. This allows for a quick restoration of power.

A very fast relay that initiates a rapid shutdown of the feeder circuit breaker when a fault is detected.

A relay that monitors the temperature of the transformer's oil and windings, and also triggers alarms if the oil level drops too low.