How to eliminate interference issues in partial discharge tester testing:
(I) External interference
1. Interference unrelated to the power supply voltage
This type of interference is unrelated to the power supply voltage (the voltage applied to the test object); it does not change with the rise or fall of the power supply voltage. It originates from: the opening and closing operations of electrical switches, arc striking in welding, crane operation, brushes of rectifier motors, flash lamps, radio electromagnetic waves, and various industrial interferences, etc. These interferences invade through pathways such as the power supply, test circuit, and ground wire.
2. Interference related to the power supply voltage
This type of interference generally increases with the rise of the power supply voltage. It can be generated by various parts within the test area, such as: the test transformer, high-voltage leads, the ends of the test object, poor contact in high-voltage lines, contact between insulating objects in the high-voltage test area and the ground wire (or grounded metal objects), poor grounding of metal objects in the test area, and induced discharge from other objects, etc. The intrusion pathways of interference related to the power supply voltage can invade the test circuit through the power supply, high-voltage conductors, space, and ground wire.
(II) Methods for eliminating external interference in partial discharge testers
1. Methods to eliminate interference unrelated to the power supply voltage: Measures should be taken in terms of power supply, space, and grounding methods. To eliminate interference from space electromagnetic waves, the test room should be shielded. For interference invading from the power supply, isolation transformers and filtering devices are generally added at the power inlet. To eliminate interference from the grounding grid, a single-point grounding method should be adopted.
2. Measures to eliminate interference related to the power supply: The high-voltage conductors can be thickened (using thicker corrugated pipes, thin iron sheet cylinders, or aluminum cylinders); anti-corona shields should be added to the ends of the test object; all ground wires and metal objects in the test area should be well grounded; insulating objects in the test area are strictly prohibited from contacting metal grounding bodies; there should be no metal objects such as screws or ground wire ends on the ground below the high-voltage lines.
