The HWI test determines a polymeric material’s resistance to ignition when exposed to abnormally high temperatures resulting from a component failure such as a conductor carrying far more than its rated current.
For doing the evaluation take a test specimens (5″ X 0.5″ X minimum part thickness), then wrapped with wire that dissipates a specified level of electrical energy. Apply power, and start timing! Use the table below to know where you are.
HWI is the time it takes to either ignite or burn through a specimen.
|These times are grouped into Performance Level Categories or PLCs:|
|HWI Mean Ignition Time (Seconds)*||PLC**|
|120 and longer||0|
|60 through 119||1|
|30 through 59||2|
|15 through 29||3|
|7 through 14||4|
|*A longer Ignition Time is better|