Slaughter 6330 - Advantages and Disadvantages of AC Testing and DC Testing; AC Testing Characteristics; AC Testing Advantages

INTRODUCTION
9
For example, a product designed to operate in the range between 100 to 240 volts can be
tested between 1,000 to 4,000 volts, or higher. Most "double insulated" products are
tested at voltages much higher than the "rule of thumb."
Testing during development and prototype stages is more stringent than production line
testing because the basic design of the product is evaluated. Design tests are usually
performed on only a few samples of the product. Production line tests are performed on
every item as it comes off the production line.
The Hipot tester must also maintain an output voltage between 100% and 120% of
specification. The output voltage of the Hipot must have a sinusoidal waveform with a
frequency between 40 to 70 Hz and has a peak waveform value that is not less than 1.3
and not more than 1.5 times the root-mean-square value.
Advantages and Disadvantages of AC Testing and DC Testing....
Please check with the Compliance Agency you are working with to see which of the two
types of voltages you are authorized to use. In some cases, a Compliance Agency will
allow either AC or DC testing. However, in other cases the Compliance Agency only
allows for an AC test. If you are unsure which specification you must comply with,
please contact our SALES DEPARTMENT at 1-800-504-0055.
AC testing characteristics
Most items that are Hipot tested have some amount of distributed capacitance. An AC
voltage cannot charge this capacitance so it continually reads the reactive current that
flows when an AC voltage is applied to a capacitive load.
AC testing advantages
1. AC testing is generally more accepted by safety agencies than DC testing. The
main reason for this is that most items being Hipot tested will operate at AC
voltages. AC Hipot testing offers the advantage of stressing the insulation
alternately in both polarities, which more closely simulates stresses the product will
normally see.
2. Since AC testing cannot charge a capacitive load the current reading remains
consistent from the initial application of the voltage, to the end of the test. There is
no need to gradually bring up the voltage since no stabilization is required to
monitor the current reading. Unless the product is sensitive to a sudden application
of voltage, the operator can immediately apply full voltage and read current without
any wait time.
3. Since AC voltage cannot charge a load there is no need to discharge the item under
test after the test.