Punjab PSEB Sr. Sec. NSQF Power (Distribution Lineman) flashcards

34 cards. Read the term and the definition here. The deck at the top of this page is optional.

Ohm's Law

Current through a conductor is directly proportional to voltage and inversely proportional to resistance, expressed as V = I × R.

Power Factor

The ratio of real power in kW to apparent power in kVA, equal to cos φ. A low value means more current for the same useful power.

RMS Value

The effective value of an alternating quantity, equal to peak value divided by the square root of two, or 0.707 times the peak.

415 V Four-Wire System

Three-phase low-voltage distribution with 415 V between lines and 240 V between any line and neutral, used for mixed domestic and small industrial loads.

Radial Distribution System

A layout where each consumer is fed from a single path from the source, simple and cheap but with no alternative supply on failure.

Distributor versus Feeder

A feeder is designed on current-carrying capacity and has no consumer taps; a distributor is tapped along its length and is designed on permissible voltage drop.

Sag Formula

For a level span, sag equals weight per unit length times span squared divided by eight times tension, showing sag rises with span and falls with tension.

Corona Effect

Ionisation of air around a conductor when surface voltage gradient exceeds about 30 kV/cm, causing power loss, audible noise and radio interference.

Ferranti Effect

Rise of receiving-end voltage above sending-end voltage on a long lightly loaded line, caused by charging current through line capacitance.

ACSR Conductor

Aluminium conductor steel reinforced: aluminium strands around a steel core, giving low weight, low cost and high tensile strength for long spans.

Pin Insulator

A rigid insulator fixed on a pin or cross-arm, used up to about 11 kV, where the conductor is tied with binding wire in a groove.

Creepage Distance

The shortest path along the insulator surface between line and earth; it must be increased in polluted coastal and industrial areas to prevent tracking.

Transformer EMF Equation

The induced EMF equals 4.44 times frequency times turns times maximum flux, showing voltage per turn is fixed by core flux and frequency.

Buchholz Relay

A gas-operated protective device fitted between transformer tank and conservator that alarms on slow gas accumulation and trips on violent oil surge.

Open-Circuit Test

A transformer test with one winding open that measures no-load current and iron loss, which stays constant at all loads.

Stay Wire Angle

A guy wire set at about 45 degrees to the ground, anchored in undisturbed soil, to resist the unbalanced pull at angle and terminal poles.

Earth Resistance Limit

The maximum measured resistance of a substation earth electrode, commonly 5 ohms for distribution substations and 1 ohm for large stations.

Tension Stringing

Pulling conductors under controlled tension with a puller and tensioner so they do not drag on ground, crops or roads during erection.

Sag Template

A sighting board or chart used to set the correct conductor sag for the ruling span and conductor temperature during stringing.

XLPE Cable

Cross-linked polyethylene insulated cable with conductor and insulation screens, used for modern distribution because it withstands higher temperature than PVC.

Stress Cone

A shaped termination of the insulation screen that spreads the electric field at a cable end, preventing tracking and breakdown at joints and terminations.

Cable Bending Radius

The minimum radius, about twelve to fifteen times cable diameter, below which a cable must not be bent or its insulation and screens are damaged.

Multiplying Factor

The CT ratio times PT ratio applied to a meter reading for high-voltage metering, giving the actual energy consumed at the primary side.

RCCB Function

A device that trips on imbalance between phase and neutral current, protecting people from earth leakage but not from overload or short circuit.

Permit to Work

A written authorisation issued after isolation, locking, tagging and earthing, naming the circuit and work, and signed before work starts.

CPR Compression Ratio

Thirty chest compressions at 100 to 120 per minute with 5 to 6 cm depth, followed by two rescue breaths, repeated until help arrives.

Prove Dead

Testing an isolated circuit with a voltage detector to confirm zero voltage before applying temporary earths and touching conductors.

Megger Test Voltage

Insulation resistance is measured at 500 V for low-voltage circuits and at 1 kV or 5 kV for high-voltage cables and machines.

Fall-of-Potential Method

An earth resistance test using current and potential spikes driven at specified spacing, with the electrode under test connected to the instrument.

Thermography

Infrared imaging of joints, conductors and insulators to find abnormal temperature rise caused by loose connections or overload before failure occurs.

Shift Handover Record

A written note of circuits isolated, permits issued, work in progress and equipment out of service, passed to the next shift for continuity.

Break-Even Point

The sales volume at which total revenue equals total cost, so the business makes neither profit nor loss; used to price contract work.

NSQF Level for Lineman

The Power Distribution Lineman job role is placed at NSQF Level 4, with progression to supervisor roles at higher levels through experience and assessment.

Risk Assessment

A structured evaluation of a task that rates each hazard by likelihood and severity, then sets controls before work begins.