S/M P/M SPARK GAP CTLG - Teledyne Reynolds

1 Electronic Products DivisionSanta Maria, California Reynolds INDUSTRIES INCORPORATED APPLICATIONS HANDBOOKT ransient Protection ProductsGas TubesHybrid Protection SystemsElectronic Products Division Reynolds INDUSTRIES INCORPORATEDABOUT REYNOLDSR eynolds Industries was founded in 1948 and has grown to be one of the largest privately heldnon-conglomerate companies specializing in the design and manufacture of electrical connec-tors. In addition to electrical connectors, Reynolds manufactures gas discharge tubes (sparkgaps), transient protection products, exploding bridgewire and exploding foil ordnance, relatedelectronic firing systems, and high voltage/high energy density capacitors.

2 Our facilities inMarina del Rey, California, near the Los Angeles airport, house our General Offices as well asthe Connector Products Division and the Electro-Ceramic products This 100,000square foot facility is fully air conditioned creating a white room atmosphere to provide theultimate in quality products and manufacturing separate facility in northern California, accommodates our ordnance subsidiary , Electronic Products Division, located in Santa Maria, California, midway between SanFrancisco and Los Angeles has capabilities for the design, development and manufacture ofhigh voltage/high energy density capacitors, voltage multiplier products, gas discharge tubes ( SPARK gaps) and transient protection also has manufacturing facilities in the United Kingdom and Switzerland and salesoffices in France and Products Division Reynolds INDUSTRIES INCORPORATEDINTRODUCTIONGAS DISCHARGE TUBESAPPLICATION INFORMATION3-4 CONSTRUCTION AND TYPICAL APPLICATION CIRCUITS5 SELECTING A GAS TUBE6-8 ORDERING INFORMATION 9 STANDARD MODELS DIAMETER SURGE CURRENTMICRO-ARC 0.

3 187" DIA. 1000 AMPS 9 MILLI-ARC " DIA. 10,000 AMPS10 MILLI-TRIARC " DIA. 10,000 AMPS10(Three Electrode Type)DECI-ARC " DIA. 20,000 AMPS11 DEKA-ARC " DIA. 40,000 AMPS11 HYBRID PROTECTION POWER PROTECTORS16IN SERIES GAS DISCHARGE TUBES17 TRANSIENT LIMITERS18 DEFINITION OF GAS DISCHARGE TUBE BREAKDOWN:The voltage at which the initial discharge occurs witha slowly rising voltage applied across the electrodesof the tube.

4 (The test voltage is applied at 100 volts persecond or less).IMPULSE BREAKDOWN:The voltage at which the initial discharge occurs witha rapidly rising voltage applied across the electrodesof the tube. This breakdown voltage is a function ofthe rate of rise of the applied voltage and is generallystated for a particular ramp CURRENT:The surge current capability of a gas tube is a functionof the waveshape of the surge and of the tube gas tube design has its own inherent maximumsurge current capability for a given surge such as tube and electrode size, gas fill, andgas pressure determine the tube RESISTANCE:The insulation resistance between electrodes of a gastube is normally measured at 100 volts DC when thegas tube is in a non-ionized condition.

5 As the device isused this insulation resistance decreases and normallyend of life is determined when this resistance reaches aselected STROKE CURRENTS:In selecting a particular gas tube for a lightning protec-tion application, the magnitude of the stroke currentmust be predicted. Lightning stroke peak currents varygreatly from several hundred to several hundredthousand amperes depending on the particularstroke and whether it is induced into the equipmentbeing protected or arrives as a direct stroke throughan electrical or ELECTROMAGNETIC PULSE:The electromagnetic radiation associated with a ther-monuclear explosion and the electrical transient coupledinto circuitry due to this REGION.

6 The first significant current that flows following initiation of an overvoltage Products Division Reynolds INDUSTRIES INCORPORATED CONTENTS2 Gas tubes (gas filled SPARK gaps) are basically high energy voltage controlled switching devices. They are unique in their ability to repeatedly switch currents of thousands of amperes, which leads to their most common usage as transient protectors for applications where high energy transient electrical surges are basic design and operation of a gas tube SPARK gap issimple. If two metal electrodes are separated by a suitable insulator and a gas placed between the electrodes at aTo initiate the arc in a gas tube, a voltage considerablyhigher than the arc voltage must be applied.

7 Figure Iillustrates the current-voltage characteristic of a typicalgas a voltage is applied across the electrodes of the tubethis voltage must be raised until it reaches the initiationpoint before current begins to flow. This initiation voltageis both a function of the device design and the rate at whichthe input voltage is applied. Characteristically gas tubesrequire higher initiation voltages the more rapidly the inputvoltage is applied. The first current that flows followinginitiation is the glow current. Over a narrow band of lowamperage currents an associated glow voltage occursacross the electrodes which is essentially independent ofcurrent.

8 This low amperage area is called the glow regionand it is the normal operational region of the voltageregulator type of gas SPARK gap protection devices are not designed foroperation in this glow region due to the current limitationsof the region, but are intended for use in the arc area whichoccurs as current is provided beyond the glow the application of SPARK gap gas tubes , two fundamentalsfrom Figure I are of importance. First, the applied voltagemust reach the initiation voltage before breakdown canoccur and second, in order for the arc to extinguishfollowing the initiation of the breakdown, the voltage curvemust be retraced back through the glow IL-A shows a basic application for a gas tube usedas a protective device.

9 The gas tube is placed across theinput terminals of the circuit load to be protected. Becauseof its high inherent impedance the gas tube is essentiallyundetected by the normal signal voltages, however withthe arrival of a transient voltage of sufficient magnitudethe gas tube goes into its arc state, thus placing a very lowimpedance across the load for the duration of the lI-B illustrates the same basic application except fora three electrode gas tube on a balanced pair is apparent from the current-voltage characteristics ofFigure I that a breakdown or initiation voltage selected forthe gas tube must be above the normal signal voltage toprevent unwanted breakdown of the protector.

10 In addition,if the incoming lines include a voltage, considerationmust be given to the current-voltage requirements of thegas tube to allow it to extinguish following initiation of thetube by a transient voltage. Extinction of the are where thesource is an AC voltage is relatively direct due to the zerovoltage crossover point which occurs with each all but simple communication and data lines, applica-tion of gas tubes involves the combination of the gas tubewith other circuit devices to fulfill the requirements of thecurrent-voltage relations of the gas tube. For all applica-tions, selection of a gas tube device with the proper currentcapacity, coordinated with the expected transient, is pressure, an electrical breakdown occurs betweenthe electrodes following the application of sufficient volt-age across the electrodes.