The energy absorbed in the impact test. (See impact test.)

A cold forming process, usually at ambient temperature, in which the metal is forced to flow by impact of a punch. The flow could be either around the punch, called backward extrusion, forming a tube with a solid bottom, or through another opening.

The energy absorbed in the impact test. (See impact test.)

A test to determine the toughness, or resistance to shock or impact, of a material. The energy absorbed in fracturing a test piece, usually notched, by a blow of high velocity is determined. The most common tests are Izod, Charpy and Fremont, each having its individual test piece dimensions and method of delivering the blow. See Izod Test and Charpy.

Device used to punch new conductor.

Electrical impedance is the complex property of an electrical circuit, or the components of a circuit, that opposes the flow of an alternating current. Ohms is the unit if measure. For a cable, its reading represents the total resistance that the cable presents to the electrical current passing through it. At low frequencies the impedance is largely a function of the conductor size, but at high frequencies, conductor size, insulation material and insulation thickness all affect the cable’s impedance. Matching impedance is very important. If the system is designed to be 100 Ohms, then the cable should match that impedance, otherwise error-producing reflections are created.

Sudden change in the impedance of a cable, often caused by twisted sections un-twisting or other cable faults.

A condition in which the impedance of a particular circuit cable or component is the same as the impedance of the circuit, cable or device to which it is connected.

Connecting cables and devices, which have the same impedance value in ohms.

A transformer designed to match the impedance of one circuit to that of another.

1) When referring to the physical condition of a part of metal product, and departure of a part of metal product, any departure of a quality characteristic from its intended level or state. The existence of an imperfection does not imply nonconformance, nor does it have any implication as the usability of a product or service. An imperfection must be rated on a scale of severity, in accordance with applicable specifications, to establish whether or not the part or metal product is of acceptable quality. 2) In crystallography, any deviation from an ideal space lattice.

More usually known as Standard Wire Gauge.

See British Standard Wire Gauge.

To fill the voids and interstices of cable or the fabric of a cable with a compound.

A mass-impregnated paper-insulated cable with a mechanically reinforced lead sheath in which the space inside the lead sheath is brought up to a high pressure by the in­troduction of inert gas in contact with the dielectric. Appreciable sheath clearance is required for single-core cables while lead pipe gas channels are included in three-core designs.

Thermo­setting artificial resins based on melamine, urea, phenol and alkyds are extensively used for temperature ratings up to 1,200°C (1,920°F). They have relatively short setting times and have advantages over earlier materials in setting and curing in the inner layers of the winding.

In the mass impregnation process, paper insulated cables are wound on a drum or in a circular tray that is placed in a heated tank to dry the insulation at low pressure. Hot impregnating compound is then admitted and the vessel maintained at about 1,200°C (1,920°F) under positive pressure. The total drying and impregnating time is of the order of 20 to 70 hours depending on cable type and voltage.

A surge of unidirectional polarity.

The ratio of the flashover, sparkover or breakdown voltage of an impulse to the crest value of the power-frequency flashover, sparkover or breakdown voltage.

The voltage breakdown of insulation under voltage surges on the order of microseconds in duration.