IEC60695-2-20 Flammability Testing Equipment Hot wire ignition tester With Electrical control

Standard:

IEC60950-1 Information technology equipment – Safety – Part 1: General requirements Annex A.4 Hot wire ignition test;

IEC60947-1 Low-voltage switchgear and controlgear –Part 1: General rules Annex M M.1 Hot wire ignition test (HWI);

IEC60695-2-20 Fire hazard testing — Part 2: Glowing/Hot wire based test methods — Section 20: Hot-wire coil ignitability test on materials.

Description of test apparatus:

The sample shall be fastened in a fixture which provides two supporting posts positioned 70 mm apart to support the test specimen in a horizontal position, at a height of 60 mm above the bottom of the chamber, in the approximate centre of the test chamber (see Figure M.1 ).

A 250 mm ± 5 mm length of NiCr-wire (80 % nickel, 20 % chromium, iron free) approximately 0.5 mm diameter and having a cold resistance of approximately 5.28 Ω/m and a length-to-mass ratio of 580 m/kg shall be used. Prior to testing, the wire shall be connected in a straight length to a variable source of power which is adjusted to cause a power dissipation of 0.26 W/mm in the wire for a period of 8 s to 1 2 s.

After cooling, the wire shall be wrapped around a sample to form five complete turns spaced 6.35 mm ± 0.05 mm apart. A winding fixture shall be used, which will uniformly position the wire in the centre portion of the sample with a winding force of 5.4 N ± 0.02 N.

The ends of the wire shall be connected to the variable power source.

The supply circuit capacity shall be sufficient to maintain a continuous linear 48 Hz to 62 Hz power density of at least 0.31 W/mm over the length of the heater wire at or near unity power factor. The power density of the supply circuit at 60 A and 1.5 V shall be approximate 0.3 W/mm. It shall be possible to adjust the power level, smoothly and continuously and measure the power to within ±2 %.

Parameter: