VOLTECH AT3600 USER MANUAL TRANSFORMER TESTS
TESTS AND TEST CONDITIONS VPN 98 - 024 PAGE 7.1.49.
In programming the AT3600 you may select the voltage (from 100V to 5kVrms), the
frequency (50Hz / 60Hz at the full voltage, or up to 1kHz at reduced voltage), the
current trip level (10µA to 30mApeak), and the ramp up and dwell times, all to suit
the specification of the transformer under test.
Many transformer specifications require Hi-Pot testing to be carried out with a dwell
time of 60 seconds. Although the transformer must be designed and constructed to
meet this, it is common practice to reduce the dwell time for production testing.
This is recognised by IEC 742, which permits a dwell time of 2 seconds for
production testing. Although not required by IEC 742, it is good practice to increase
the test voltage by say 10% when performing reduced-time testing, to provide
additional security for the test.
IEC742 has been replaced by IEC61558, which specifies 1 second for production
testing. Details are available on the IEC web-site (http://www.iec.ch).
During a Hi-Pot test, the Wattage is continuously monitored and adjusted to provide
the correct output. If the programmed output voltage cannot be maintained, the tester
will automatically display ‘FAIL’, illuminate the red indicator, return a ‘FAIL’ to the
server (if used) and sound a warning buzzer (if enabled). This method complies with
the production requirements of EN61558-1 (1998), UL1411, 5
th
Edition and others.
Special Notes:
Under certain test conditions the measured current will be higher than the allowed
minimum limit due to parasitic effects on the AT3600 and any connected fixture system.
The maximum parasitic effect created by the AT3600 with every node being used on an
HPAC test can be calculated by:
I
p
= V*(4.614*10
-10
+ 9.1*10
-11
*f) where V = Test voltage and f = test frequency.
This works out to be 12.5uA at 2.5KV @ 50Hz.
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