- How long should I dwell a Hi-Pot test?
- How accurate are the Ramp and Dwell times during Hi-POT?
How long should I dwell a Hi-Pot test:
All safety transformers, including power and signal transformers inside power supplies, must be tested to ensure that they are safe and will remain safe during normal operation.
An important test is that of dielectric strength or Hi-Pot (HI POTential).
The voltage is typically 2000 or 4000V. The exact test depends on the construction and insulation of the transformer will be defined by the standard in use. During the design or type-test of a transformer it is normal to apply Hi-Pot for 1 minute or more.
This is not practical in production and the standards recognize this. For example, Annex L, Routine tests (production tests) of EN61558-1 states that "The manufacturer may use a test procedure which is better suited to his production arrangements...", and states specifically for Hi-Pot that "The specified test voltage is applied for 1s"
The programmable Hi-Pot test dwell time of the AT3600 means that any duration may be used but Voltech's suggestion is that a routine production test should be of 1s only.
See attached Voltech article: 104-003-0-5A Hi-pot Declaration
How accurate are the Ramp and Dwell times during Hi-POT?:
Ramp up and dwell times have a timing accuracy of 10mS
A test may have a slightly longer dwell time, particularly on the first run. This is because the voltage may not be correct after the ramp up period so a trim iteration may be needed where the tester measures and corrects the voltage.
In summary, Voltech guarantee ramp up and dwell periods are within 10mS of the specified periods.