Glow Wire Test Cabinet

Insulating materials in electrical equipment need to resist ignition from thermal stresses induced by non-flaming glowing sources, for short periods. The performance of the internal materials cannot affect the fire safety of equipment. The FTT Glow Wire Apparatus (IEC 60695-2-20, ASTM D6194) can be used for tests to assess the glow wire flammability index (GWFI; IEC 60695-2-12) and the glow wire ignition temperature (GWIT; IEC 60695-2-13). GWFI is the highest temperature which satisfies one of the following: (a) there is no flame and no glowing (no ignition) or (b) burning or glowing time is less than 30 s after removal of the glow wire and cotton under the specimen does not ignite. GWIT is a temperature 25°C higher than the maximum temperature of the glow wire tip which does not ignite the material.

The maximum allowed flame development time is 5 s. GWIT is a requirement for polymeric materials used in electrical equipment in accordance with UL 746A/C.

In the Glow Wire Apparatus, a wire is electrically heated to an adjustable temperature. The specimen is brought into contact with the glow-wire by a motor-driven sliding carriage. At the end of the prescribed time the specimen is automatically returned to the starting position. GWFI and GWIT are evaluated for the specimen.

Features

  • 0.5 mm diameter Cr/Al glow wire, temperature measured by insulated junction thermocouple
  • Motorized specimen carriage preloaded with 1.0 N force with stepper motor, movement towards glow wire
  • Universal, adjustable stainless steel perforated tray mounting bracket for fixing specimen position
  • Adjustable current source to heat and maintain glow wire temperature
  • Burner, burner wing tip and support for angle adjustment according to ASTM D5025, with burner calibration kit according to ASTM D5207
  • Digital processor control unit to control glow wire application time, test duration and to record flame timing

 

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