ABB HCLD key terms

The minimum safe distance a worker or conductive object must maintain from exposed energized electrical equipment, based on voltage, to prevent arc flash or shock.

The boundary around energized equipment inside which a person could receive a second-degree burn from an arc flash, used to set personal protective equipment requirements.

The closest distance a qualified worker may allow any part of the body or conductive tool to come to an exposed energized conductor, calculated from voltage and switching surge factors.

A work area where all conductive objects are bonded together and to the worker so that no dangerous voltage difference can exist across the worker's body.

Temporary bonding of de-energized conductors to earth and to each other at the work site to protect workers if the circuit is accidentally re-energized.

A procedure that uses locks and tags to prevent energy isolation devices from being operated until the work is finished, protecting workers from unexpected energization.

The consensus standard that sets minimum safety rules for the installation, operation, and maintenance of electric supply and communication lines and associated equipment.

The minimum required separation distance between conductors, or between a conductor and a surface such as a road or building, specified by the NESC to ensure safety.

The point where the utility's supply conductors connect to the customer's wiring, marking the boundary between utility and customer responsibility.

The electrical point where a customer's installation connects to the utility distribution system, often used when discussing power quality and interconnection standards.

The process of keeping distribution voltage within required limits as load changes, using devices such as tap-changing transformers, regulators, and capacitors.

The reduction in voltage along a conductor caused by current flowing through its impedance, which must be limited to ensure proper customer equipment operation.

The ratio of real power to apparent power in an AC circuit, indicating how effectively current is converted into useful work; low power factor increases losses and reduces capacity.

A group of capacitors connected to a distribution circuit to supply reactive power, improve power factor, reduce losses, and support voltage.

The vertical distance between a conductor's support points and its lowest point, determined by tension, span length, and temperature, affecting clearance to ground.

The horizontal distance between two adjacent supporting structures for an overhead line, which influences conductor tension, sag, and loading.

A tensioned cable attached to a pole and anchored to the ground to resist lateral loads from conductor tension, wind, or unbalanced forces.

A buried or driven device that transfers the pull of a guy wire or structure into the earth, preventing movement of the supported pole or equipment.

A horizontal member mounted on a pole to support insulators and conductors, maintaining proper spacing and clearance between phases.

A device made of nonconductive material that supports an energized conductor while preventing current from flowing to ground or to other conductors.

The shortest path along the surface of an insulator between its energized and grounded ends, which must be long enough to prevent flashover under contaminated conditions.

An underground cable designed to be installed directly in the soil without a conduit or duct, having protective jackets suitable for burial conditions.

A group of conduits, usually encased in concrete, buried underground to carry and protect cables and allow for replacement or additional circuits.

A vault with an opening at ground level providing access to underground cables, splices, and equipment for installation, maintenance, and testing.

The longitudinal force applied to a cable during installation, which must be limited to avoid damaging the conductor, insulation, or jacket.

A group of single-phase transformers connected together to supply three-phase power or to provide a specific voltage and capacity configuration.

A transformer winding connection in which one end of each phase winding is joined at a common neutral point, providing line-to-neutral voltage and a neutral conductor.

A transformer winding connection in which the ends of each phase winding are connected to form a closed loop, with no neutral point and line voltage equal to phase voltage.

A designation describing the phase displacement and connection arrangement of a three-phase transformer's windings, such as Dyn11, indicating angular relationship between primary and secondary voltages.

A device on a transformer that adjusts the number of active turns in a winding to change the voltage ratio, either while energized (on-load) or only when de-energized (off-circuit).

A written sequence of steps for opening and closing switches and devices to safely configure the system for work or to restore service, including verification and tagging.

An air gap in a circuit created by opening a switch or disconnector, allowing workers to visually confirm that the circuit is isolated from all energy sources.

A self-controlled switching device that automatically interrupts and re-closes a circuit a set number of times to clear temporary faults and restore service quickly.

A switch that counts fault-current interruptions and opens during a subsequent de-energized interval to isolate a faulted section, typically used with a recloser.

A device that monitors current, voltage, or other quantities and initiates tripping of a circuit breaker or switch when it detects a fault or abnormal condition.

The selection of protective device settings so that the device closest to a fault operates first, minimizing the number of customers affected by an outage.

A test that applies a DC voltage to measure the resistance of insulation, detecting moisture, contamination, or deterioration that could lead to failure.

An instrument that applies a high DC voltage and measures very high resistance values, commonly used for insulation resistance testing of cables and equipment.

A test that applies a high voltage to insulation to verify its ability to withstand electrical stress without breakdown, often performed on cables and transformers.

A dielectric withstand test that applies a voltage significantly higher than operating voltage to check insulation integrity and detect defects before energization.

The process of finding the physical position of a fault on a distribution circuit using methods such as fault indicators, thumping, time-domain reflectometry, or sectionalizing.

A technique that sends a pulse down a cable and measures the time and shape of reflections to locate opens, shorts, or impedance changes along its length.

A device installed on a line that senses fault current and provides a visual or remote indication that the fault is downstream, helping crews locate the problem.

A fault-location method for underground cables that repeatedly applies high-current pulses to create an audible thump at the fault, allowing crews to pinpoint its location.

An aerial lift vehicle with an insulated boom and bucket used to position workers near overhead lines for construction, maintenance, and troubleshooting.

An insulated tool, often telescoping, used by workers to operate switches or handle conductors at a safe distance from energized equipment.

Rubber gloves with a protective leather cover worn by workers to provide electrical insulation when working near energized conductors, rated by voltage class.