Spark Gap

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spark gap

[′spärk ‚gap]
(electricity)
An arrangement of two electrodes between which a spark may occur; the insulation (usually air) between the electrodes is self-restoring after passage of the spark; used as a switching device, for example, to protect equipment against lightning or to switch a radar antenna from receiver to transmitter and vice versa.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Spark Gap

 

an air gap separating the electrodes of high-voltage equipment. A distinction is made between protective and separating spark gaps.

A protective spark gap guards insulation from overvoltage and the effects of electric arcs. In such a gap (see Figure l,a) the metal electrodes (1) and (2) are connected in parallel with the insulation being protected. The insulator is not exposed to the effects of the arc, since the arc is established across the air gap l (which is smaller than l1). Protective spark gaps are classified according to the shape of their electrodes as rod gaps (Figure l,a) and ring gaps (Figure l,b).

Figure 1. Protective spark gaps: (a) rod-type, (b) ring-type

A separating spark gap is the main component of a valve arrester. This type of gap protects the operating resistor OR of the gap (Figure 2, a) from the effects of the rated voltage of the device. The resistors R are used to equalize voltage distribution over the spark gap G. The overvoltage wave is shunted to ground through the operating resistor, and the arc of the accompanying current of industrial frequency (50 hertz) is extinguished by being broken into short arcs across the individual spark gaps (see Figure 2, b).

An isolating spark gap is made up of two, four, six, or more spark gap units. The air gap of a spark gap unit is usually about l mm; the number of units is based on one gap per kilovolt of rated voltage.

Figure 2. Valve arrester: (a) diagram of spark gap, (b) spark gap unit

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

Spark gap

The region between two electrodes in which a disruptive electrical spark may take place. The gap should be taken to mean the electrodes as well as the intervening space. Such devices may have many uses. The ignition system in a gasoline engine furnishes a very important example. Another important case is the use of a spark gap as a protective device in electrical equipment. Here, surges in potential may be made to break down such a gap so that expensive equipment will not be damaged.

McGraw-Hill Concise Encyclopedia of Engineering. © 2002 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Such a scheme allows one to obtain nanosecond pulses with amplitude of hundreds of kilovolts and more on the load by using a linear pulse transformer as a stepup pulse transformer having one turn in the secondary winding and a high-speed spark gap as the closing switch SD.
Ignition energy Spark plugs Spark gaps (mm) Coils (mJ) NGK DPR8EA-9 10 (15.1 k V) (1) Bosch 78 NGK DPR8EIX-9 15 (20.2 k V) (1) F000ZS0105 84 NGK DP8EA-9 20 (15.1 k V) (1) CM Racing 377 30 (15.1 k V) (1) 496 (1): according to Equation (2).
(2000), also considers pressure, temperature and spark gap, in according with Equation 2:
For the constructed test bench, the Paschen's Law variables was simulated only by spark gap variation between the electrodes, in other words, the Equation (1) right side numerator product will be represented only by the electrodes gap, while the environmental conditions are the local atmospheric, monitored during the trial.
The spark duration has insignificant variation with the spark gap, and the delay time is slightly increased as function of gap (but, smaller than inductive system in all conditions).
Dual-use items are those, like triggered spark gaps, that are under export restrictions because they have both peaceful and weapons applications.
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Throughout the summer of 2003, as Karni prepared to face Eagle in the heating room, he was simultaneously negotiating with Pakistani contacts to cement a deal to supply them with triggered spark gaps. The negotiations were not as private as Karni presumed.
where [[sigma].sub.c] =5.67 x [10.sup.-8] W x [([m.sup.2] x [K.sup.4]).sup.-1] is the Stefan-Boltzmann constant [12]; [t.sub.m] is the time (in seconds) corresponding amplitude [I.sub.mL] (in Amperes) of lightning current on the electrical percolation stage in its long air spark gap pulse A-component of powerful lightning current.
However, no unit with a ball electrode achieved a 1-mm spark gap thought to be a necessary minimal threshold to permit depth-perception distinction.