Glow wire tester

Glow wire tester Discussion of the Glow Wire Test (Varies as per relevant standard): 1. Object of the Test - Components or parts under Fault or Overload conditions, may attain a Temperature such that they will ignite parts in their vicinity. The GLOW - WIRE Test simulates thermal stresses which may be produced by such source of heat or ignition. e.g. glowing elements or overloaded resistors, may be for short duration, in order to assess by a simulation technique the Fire Hazard. 2. General Description of the Test - a. If possible, the specimen should be a complete equipment, sub-assembly or a component. b. While taking a part / parts of an enclosure for the Tests, care must be taken to ensure that the Test Conditions are not significantly different from those occurring in the Normal usage, with regard to shape, ventilation, effect of thermal stress and possible flames occurring, burning or glowing particles falling in the vicinity of the specimen. c. The Test is applied to ensure - 1. That the Glow - wire Loop which is electrically heated to a temperature specified, does not under defined conditions cause ignition of the Part/Parts. 2. That the part which might have been ignited, has a limited duration of burning, without spreading of fire by its flame or burning or glowing particles. d. This type of test may not be appropriate for too small components / parts / sub assemblies, which may need Needle Flame Test. 3. Test Apparatus - a. The Glow - Wire consists of a specified loop of a Nickel / Chromium ( 80/20 ) wire of 4 mm dia. b. Sheathed fine wire thermocouple, of overall dia. 0.5 mm ( wires of NiCr & NiAl ) with welded point / joint located in the 0.6 mm hole in the Loop of Glow - Wire. c. The Sheath consists of metal , resistant to a temperature of 960 deg. C in working. d. The instrument for measuring thermovoltage have 1 % accuracy. e. The Test Apparatus is so designed that the Glow - Wire Loop is horizontal and the mounted specimen moves horizontally towards the Loop with a force applied 0.8 to 1.2 N, for a penetration distance of 7 mm max. f. To evaluate the possibility of spread of fire, a layer of the material or components normally surrounded underneath the specimen is placed underneath the specimen at a distance equal to the distance between the specimen and the surrounding material or components when the specimen is mounted as in normal use. If a subassembly or a part of the equipment is tested separately, a piece of white pinewood board, approximately 10 mm thick and covered with a single layer of tissue paper, is positioned at a distance of 200+/- 5mm below the place where the glow-wire is applied to the specimen, unless otherwise specified in the relevant specification.