IEEE 1783:2009 pdf free download – IEEE Guide for Test Methods andProcedures to Evaluate the Electrical Performance of Insulators in Freezing Conditions
dry snow: Type of precipitation icing of 50 kg/m’to 100 kg/m’density resulting in very light packing ofsnow onto various shapes and structures.Adhesion strength is weak and the accretion can be easilyremoved by wind or motion. Accretion of various shapes depending on wind speed and torsional stiffnessof conductor. When the temperature is close to zero, its liquid water content may increase, causing theaccretion to fall off. If the temperature drops after accretion, adhesion strength may become very strong.
equivalent salt deposit density (ESDD): The amount of sodium chloride (NaCl) that, when dissolved indemineralized water, gives the same volume conductivity as that of the natural deposit removed from agiven surface of the insulator divided by the area of this surface; generally expressed in mg/cm2′.
error: Any discrepancy between a computed,observed, or measured quantity and the true, specified, ortheoretically correct value or condition.
external insulation: Insulation that is designed for use outside of buildings and for exposure to theweather.
fifty percent disruptive discharge (flashover) voltage: The voltage that has a 50% probability ofproducing a disruptive discharge.
NOTE—The term mostly applics to impulse tests and has significance only in cases when the loss of clectric strengthresulting from a disruptive discharge is temporary.
flashover: A disruptive discharge through air around or over the surface of solid or liquid insulation,between parts of different potential or polarity，produced by the application of voltage wherein thebreakdown path becomes sufficiently ionized to maintain an electric arc.
freezing drizzle: Drizzle that falls in liquid form but freezes on impact to form a coating of glaze upon theground and on exposed objects.
freezing rain: Rain that falls in liquid form but freezes on impact to form a coating of glaze upon theground and on exposed objects.
glaze ice (clear ice): Type of precipitation icing resulting in pure ice accretion of density 700 kg/m’ to900 kg/m’, sometimes with the presence of icicles underneath the wires. It very strongly adheres to objects,and is difficult to knock off.
hard rime: Type of in-cloud icing resulting in ice accretion of density 300 kg/m’to 700 kg/m’characterized by an homogeneous struicture with inclusions of air bubbles. It takes a pennant-shaped aspectagainst the wind on stiff objects, but a more or less circular shape on flexible cables. It strongly adheres toobjects and is more or less difficult to knock off, even with a hammer.
hoarfrost: A deposit of interlocking ice crystals (hoar crystals) formed by direct sublimation on objects,usually those of small diameter freely exposed to the air such as tree branches, plant stems and leaf edges,wires, poles, etc.The deposition of hoarfrost on an object is similar to the process by which dew is formed,except that the temperature of the object shall be below freezing. It forms when air with a dew point belowfreezing is brought to saturation by cooling.A type of precipitation icing of very low density (less than100 kg/m’) resulting in ice crystal deposits, characterized by very low adhesion.
ice thickness: The radial thickness of ice accumulation measured on a rotating monitoring cylinder.
ice progressive stress (IPS): A test method where continuous ice exposure under line potential continuesuntil flashover or equilibrium occurs.