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[FAQ] What’s the difference between Single Protection and Double Protection rating in UL 1577?

Darrah Merillat
Genius 16870 points

What’s the difference between Single Protection and Double Protection rating in UL 1577?

  • 0
    TI__Genius 16870 points

    Double Protection isolators need to pass 2 additional tests when compared to Single Protection isolators.

    Single protection isolators are required to pass the following 3 tests:

    1- Dielectric Voltage-Withstand Test

    2- Overload Test

    3- Limited Thermal Aging Test

    Double protection isolators need to pass the tests above and the following 2 additional tests:

    4- 20 kV Discharge Test

    5-  1008 Hours Isolator Life Test

    Additionally, UL restricts the use of Double Protection Isolators to equipment rated up to 250 Vrms whereas Single Protection Isolators can be used in equipment rated up to 600 Vrms or dc.