Power Plug Tracking Test Service

Tracking on power plugs as such does not necessarily lead to fire accidents. The problem being, rapid flaming occurs on the connection interface between the plug and the mains outlet as a result of repeated small spark discharges (scintillation). Prevention is important as this phenomenon can ignite flammable items nearby, thus likely leading to fire accidents. We at OKI Engineering provide test services to prevent such tracking from occurring.

About the Tracking Phenomenon

Tracking occurs when voltage is applied on a surface polluted with or damaged by salt, dust, moisture and chemical agents (synthetic detergents) as current flows beyond insulation creepage distance while the surface deteriorates and a carbide conductive path (track) is created with consequent insulator breakdown.

Tracking Resistance Test for Power Plugs

Test parameters are designed for tracking resistance capability of an indoor use, rated voltage 125V, rated current 15A or less, plug with molded cable.

"Tracking Resistance of Power Plugs" JWDS0028.
A standard by the Japan Electrical Wiring Devices and Equipment Industries Association, JEWA.

Level Anti-tracking performance Usage environment
Frequency of insertion/removal Location
1 Drop frequency: over 200 times low Location difficult to inspect
Moisture Location
Specific location
2 Drop frequency: over 80 times low General location
high Moisture Location
Specific location

Case Study of Tracking Resistance Test

AC Adaptor (input: AC100-240V, output: DC5V)
Test liquid (solution)
0.2% aqueous solution of ammonium chloride
Applied voltage
Power plug rated voltage of AC125V, 50Hz
Other test conditions
• Single drop amount: 20mm² (+5, -0mm²)
• Continuous dropping in intervals of 5 minutes ±10 seconds
• Drop frequency: 80 times
• Test circuit as in Figure 1
• Used equipment: AC-stabilized power supply.

Figure 1: Test Circuit

As for the test result, we confirm that no flaming occurs from either of the following phenomena:

  • Flaming during dropping
  • Overcurrent relay or circuit breaker operation
  • Broken test outlet cover

NOTE: Not accounting for scintillation and smoke without generating fire.

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