Punjab PSEB Sr. Sec. NSQF Power (Distribution Lineman) key terms

The fixed relationship in a circuit where voltage equals current multiplied by resistance (V = I × R). Knowing any two values lets a lineman calculate the third when checking loads, drops or test readings.

The ratio of real power in watts to apparent power in volt-amperes in an AC circuit. A low value means more current flows for the same useful work, increasing losses and heating in distribution equipment.

An AC supply using three conductors whose voltages are separated by 120 electrical degrees. It gives constant power delivery, smaller conductors for a given load, and two usable voltage levels from one transformer.

The potential difference measured between one phase conductor and the neutral or earthed point. In a low-voltage three-phase four-wire system it is the phase voltage, about 230 volts on Indian distribution networks.

The loss of voltage along a conductor caused by its resistance and reactance carrying current. Excessive drop at the consumer's terminals causes dim lights, motor overheating and complaints, so it is limited by design rules.

The tendency of alternating current to concentrate near the outer surface of a conductor as frequency rises. It raises effective resistance and is one reason bundled or hollow conductors are used on high-voltage lines.

A faint violet glow, hissing and ozone smell around a high-voltage conductor where the local electric field ionises air. It wastes energy and erodes hardware, and is reduced by larger conductor diameter or bundled conductors.

Aluminium Conductor Steel Reinforced: stranded aluminium wires wrapped around a galvanised steel core. The aluminium carries current and the steel core provides tensile strength for long spans between supports.

The cross-sectional area of a conductor, usually stated in square millimetres, which fixes its current-carrying capacity and resistance. Selection balances voltage drop, heating limits, mechanical strength and cost.

The maximum continuous current a conductor or cable can carry without its insulation or joints exceeding the permitted temperature. It depends on material, cross-section, ambient temperature and method of installation.

A component of porcelain, glass or polymer that supports a live conductor and isolates it from the earthed support structure. It must withstand both the normal voltage and lightning or switching overvoltages without flashover.

The shortest path along the surface of an insulator between its live and earthed ends. It must be long enough for the pollution level of the area, otherwise moisture and dust allow surface tracking and flashover.

A single-piece porcelain or glass insulator mounted on a pin fixed to the cross-arm, used on low and medium voltage lines. The conductor is tied into its top groove with binding wire.

A series of disc insulators hanging from the tower or pole, supporting the conductor in a clamp below. Adding discs raises the voltage rating, and the string is used on higher-voltage and long-span lines.

An insulator assembly fitted where the conductor is under tension, such as at a dead-end, angle or section pole. It holds the full mechanical pull of the conductor in addition to insulating it.

The horizontal distance between two adjacent supports of an overhead line. Longer spans need taller poles, more sag control and stronger conductors, while shorter spans need more supports and hardware.

The vertical drop of a conductor between supports due to its own weight and tension. Correct sag keeps tension within safe limits and maintains the required ground clearance as temperature and loading change.

The minimum vertical distance between the lowest conductor of an overhead line and the ground, road or building beneath. It is fixed by regulations and varies with voltage and the type of area crossed.

The strip of land along a line route that must be kept clear of buildings, tall trees and obstructions. It protects the line from contact and allows safe access for construction, patrolling and repair.

The horizontal member fixed near the top of a pole that carries the insulators and holds the phase conductors at the designed spacing. Its strength and alignment directly affect conductor clearances.

A galvanised steel wire anchored to the ground and clamped to a pole to resist the unbalanced pull of conductors at angles, dead-ends and terminal points. It is set with a stay set and turnbuckle for tensioning.

A fitting that grips the conductor and transfers its full tension to an insulator string or pole at a terminal or angle location. It differs from a suspension clamp, which mainly supports weight.

A static device that steps the medium distribution voltage down to the low voltage used by consumers, typically 11 kV to 415/230 volts. It is rated in kVA and mounted on a plinth or pole.

The apparent-power capacity marked on a transformer, calculated from rated voltage and current without regard to load power factor. Loading beyond it causes overheating and shortened insulation life.

Bonding of the transformer tank, neutral and lightning arrester to earth electrodes to keep fault and surge voltages safe. Two separate and measurable earth connections are normally required at a distribution substation.

A protective device that provides a low-resistance path to earth for surge currents from lightning or switching, then restores its insulation. It is installed at substations and line entries to protect transformers.

The resistance offered by the soil and electrode to current flowing into the ground, measured in ohms with an earth tester. A low value is needed so fault current trips protection and touch voltages stay safe.

An electrical discharge across the surface of an insulator or through air between live parts and earth. It is caused by overvoltage, pollution, moisture or damaged insulation and usually trips the circuit.

An insulated conductor assembly laid below ground, protected by bedding, tiles or a duct and a warning tape. It avoids visual clutter and storm damage but needs costly excavation for faults and joints.

The set of materials and tools, including stress cones, insulation tape, ferrules and heat-shrink parts, used to remake a cable's insulation and sheath at a joint. Correct jointing restores insulation and sealing.

A post or plate placed on the surface above a buried cable to show its alignment, depth change or joint location. It prevents accidental excavation damage and speeds fault location and repair.

A device that integrates the power drawn by a consumer over time and records it in kilowatt-hours for billing. Modern static meters also log load profile, tamper events and remote readings.

Metering in which current transformers reduce the load current to a standard value for the meter, used for large consumers. The meter reading is multiplied by the CT ratio to obtain actual energy.

Fixing tamper-evident seals on meter covers, terminal blocks and service cut-outs after inspection or testing. Broken or missing seals indicate possible unauthorised interference and trigger investigation.

The arrangement of cable, cut-out, meter and earthing that connects a consumer's installation to the distributor's low-voltage mains. It ends at the consumer's terminals and is the boundary of responsibility.

Providing a low-resistance connection from the consumer's installation metalwork and neutral point to earth electrodes. It ensures protective devices operate and limits touch voltage during faults.

A written authorisation issued by the controlling engineer that states the circuit, the isolation done, the earths applied and the validity period. Work may start only after it is signed and accepted by the person in charge.

The safety routine of opening and locking off all supplies, proving the line dead with a tester, then applying temporary earths at the worksite. Earthing discharges residual charge and protects against accidental re-energisation.

A warning sign placed at the worksite and at the control point stating that men are working and the line must not be switched on. It is removed only by the person who fixed it.

An instrument used to confirm whether a conductor or terminal is live before touching it. It must be of the correct voltage range and proved on a known live source before and after the test.

A portable instrument, usually of the fall-of-potential type, that measures the resistance of an earth electrode by passing current through auxiliary spikes. Readings confirm whether earthing meets the required value.

An insulation resistance tester that applies a high DC voltage, commonly 500 or 1000 volts, to a cable or winding and shows leakage in megohms. Low readings indicate moisture, damage or ageing of insulation.

The immediate response of switching off the supply or separating the casualty with dry insulating material, then checking breathing and calling for medical help. Do not touch a person still in contact with live parts.

Chest compressions, with rescue breaths if trained, given to a casualty who is not breathing normally. It keeps blood and oxygen moving until medical help arrives and is started promptly after an electric shock.

The routine inspection of an overhead line on foot or by vehicle to find broken insulators, loose stays, tree growth, sag changes and unauthorised construction. Early detection prevents faults and outages.

The operation of pulling conductors along a line of erected supports and then tensioning and clamping them at the correct sag. It uses pilot wires, running-out blocks and pullers to avoid damage to conductors.

Setting a pole upright in an excavated pit or by boring, then backfilling and compacting with stones and soil in layers. Correct depth, plumb and compaction give the pole its stability against wind and conductor pull.

Highly refined mineral oil used in a transformer for insulation and for carrying heat from windings to the tank surface. Its dielectric strength and moisture content are checked periodically by testing.

The activity of identifying an opportunity, organising resources and taking financial risk to run a small enterprise such as an electrical contracting or repair service. It requires planning, costing and customer handling.

The general workplace abilities, including communication, teamwork, safety discipline, punctuality and basic digital and numerical skills, that make a technically trained person effective and easy to employ.

The clear exchange of instructions, readings, hazards and completion reports between linemen, supervisors and control rooms. Standard phrases, log entries and confirmation back prevent switching errors and accidents.