โก๏ธ๐Hi potential Test or Hipot test is also known as the dielectric withstand test.This test checks for good isolation & verifies the electrical insulation of the electric component with the help of the hipot test the insulation condition of the transformers,switchgears,relays,generators busbar Cables and dc high voltage Capactors are evaluated
.๐๐ฆ๐ฉ๐จ๐ซ๐ญ๐๐ง๐๐ ๐จ๐ ๐๐ข๐ฉ๐จ๐ญ ๐๐๐ฌ๐ญ โ๏ธ
๐ฏMost of the time hipot test is done as a Part of the commissioning test such as before energizing a LV or MV system.The test is done when it is needed to verify the clearance & solid insulation of component in considered electric systems have adequate dielectric strength with help of hipot test can be found out;
โช๏ธDamage insulation
โช๏ธConductive or corosive contaminants between the Conductors intended to be electrically separated.
โช๏ธIssues in terminal spacing
โช๏ธCable tolerence issues.
๐๐ ๐๐ข๐ฉ๐จ๐ญ ๐๐๐ฌ๐ญ
ใฝ๏ธ๐กIn this test an AC voltage is supplied to the contacts according to the IEC- 60502-2: 2014standard. There are 3 methods of doingthis test.
โช๏ธApply phase to phase voltage 15 minutes at a frequency between 20Hz – 300 Hz
โช๏ธApply nomal rated voltage for 24 hours. (for all 3 Cables)
โช๏ธApply rms rated voltage value which is 3 times of rated voltage for 15 minutes at a frequency of 0.1 Hz
๐ ๐จ๐ฅ๐ฅ๐จ๐ฐ๐๐ ๐๐๐ฌ๐ญ๐ข๐ง๐ ๐๐ซ๐จ๐๐๐๐ฎ๐ซ๐
โ๏ธ๐โช๏ธThe Ac input side of the hipot tester was connected to the 230V voltage supply.
โช๏ธOutput of the hipot tester was connected to the step up dry transformer using that the 230V voltage supply will be stepped up to the required Ac volage that is needed to be supplied to the contacts being tested.
โช๏ธConnected meter ports of the hitot tester with the dry type transformer.
โช๏ธConnected the dry type transformer to one of the phases to be tested and all the other phases should be connected to the earth.
โช๏ธThe hipot tester also needs to he grounded
โช๏ธAfter completing all the Connections properly, turned on the hipot tester starting from o and gradually increased the voltage to the required value to be supplied.
โช๏ธWaited until mentioned time duration in standard & after that gradually decreased the votage level to 0 .
โช๏ธThen using a conductor discharged all the cables & plate on the transformer if they had charged during the test.
โช๏ธApplied same method for all the phases.
โช๏ธApart from the transformer cables and the outgoing cables for the incoming cables from the CEB/LECO supply the DC test was conducted. (because cables are lengthy and when conducting the AC test hipot tester was tripped)