Switchgear standardization
C.C. Garrard · The journal of the Institution of Electrical Engineers · 1918
General principles underlying standardization.Standard test pressure for switch and controlling gear.Conductivity of current-carrying alloys : specifications of cast brass and gunmetal.Knife switches : millivolt drop at contacts.Suggested standards for back connection studs and nuts.Oil switches and circuit-breakers : urgent necessity of standard oil-switch rules in view of the position in foreign countries; breaking capacity; connection between breaking capacity and quantity of oil.Resistance and reactance type of oil circuit-breakers.Length of break of oil switches.Single and multiple tanks on oil switches.Amount of oil required for oil switches.Speed of operation of oil circuit-breakers.Air-break circuit-breakers : millivolt drop at brush contacts.Cut-outs: National Electric Code enclosed cut-outs; short-circuit tests on cut-outs; time element of cut-outs; determination of normal fusing current.Resistance wire: suggested British copper-nickel standards.Motor starting-gear; liquid starters.Copper strip connections of switchboards: suggested standard sections; temperature rise; millivolt drop of bolted contacts.Switchboards: cellular principle; suggestions put forward by Swiss Electrotechnical Society.Lightning protective gear : horn gaps; choking coils; lightning arresters.