Acceptance Direct Current (DC) Hi-Pot for generator
Nov 13, 2024
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Safety should always be a top priority for electrical equipment and components. To ensure that everything is in good working condition and free from any potential hazards, it is by performing acceptance testing. And one of the tests that is commonly conducted is the Hi-Pot or high potential test.
The Hi-Pot test is important in ensuring that the insulation is able to withstand the normal operating voltage without breaking down. It also helps detect any defects or weaknesses in the insulation that could result in electrical hazards.
the Hi-Pot test is usually carried out on the rotor winding and stator winding to determine the integrity of their insulation. A Direct Current (DC) voltage is applied to the windings, and the insulation resistance is measured. If the insulation is deemed to be in good condition and can withstand the test voltage, the generator can be considered to have passed the acceptance test.
Insulation systems for medium voltage generator stators are normally DC overvoltage or hi-pot tested at acceptance values after shipment or installation, or following rewinds when another party is responsible for the cost of repair and to also prove that the apparatus is fit for service. DC is used
instead of AC because of the amount of vars needed to support the insulation capacitance. The relatively high AC overload in comparison to DC necessitates the need for a high capacity large AC hi-pot test set that is relatively expensive and difficult to transport to the site. Normally, one phase is tested at a time with the other two phases grounded. The ends of the coils are connected together to reduce transient voltages in case the test is suddenly interrupted.
Wuhan Huayi Electric Power researched and developed the intelligent DC hipot tester, it can remote the voltage rising, with automatic test mode and manual test mode, high accuracy, easy to operate. The resistance value can be reading directly.
