High-Voltage Electrical Testing: Key Safety Requirements for Field Operations

• The test site layout must be reasonable and organized. High-voltage testing equipment should be placed close to the test object, live parts must be isolated from each other, and remain within the clear line of sight of test personnel.

• Operational procedures must be rigorous and systematic. Unless otherwise specified, voltage must not be suddenly applied or removed during operation. In case of abnormal conditions, voltage increase must be stopped immediately, pressure rapidly reduced, power disconnected, discharge performed, and appropriate grounding measures taken before inspection and analysis begin.

• On-site work must strictly enforce the work permit system, work authorization system, work supervision system, as well as procedures for work suspension, transfer, and completion.

• Barriers or fences must be erected at the test site, warning signs hung, and a designated person assigned for on-site supervision.

• During power-frequency partial discharge tests, no fewer than two high-voltage test personnel must be present, with the team leader being an experienced individual. Before commencement, the leader must conduct a detailed safety briefing for all test personnel.

• If electrical connections need to be disconnected for testing purposes, proper markings must be made beforehand, and checks conducted after reconnection.

• The enclosure of high-voltage testing equipment must be reliably grounded. High-voltage leads should be kept as short as possible and supported by insulating materials when necessary. To prevent discharges from any part of the high-voltage circuit to grounded objects, sufficient clearance must be maintained between the high-voltage circuit and ground.

• Before applying voltage, wiring and instrument ranges must be carefully checked to ensure the voltage regulator is at zero position and all instruments are correctly set. Only after notifying relevant personnel to move away from the test object and obtaining approval from the team leader may voltage be applied.

• When changing connections or concluding a test, voltage must first be reduced, power disconnected, and the high-voltage section of the boosting device short-circuited and grounded.

• Large-capacity test objects without installed grounding wires must be discharged prior to testing.

When the rated voltage of the test equipment differs from the actual rated operating voltage of the equipment in service, the test voltage standard shall be determined according to the following principles:

• When higher-rated-voltage equipment is used to enhance insulation, the test shall be conducted according to the equipment’s rated voltage standard;

• When higher-rated-voltage equipment is used to meet product interchangeability requirements, the test shall be conducted according to the equipment’s actual rated operating voltage standard;

• When higher-voltage-grade equipment is used to meet high-altitude or polluted area requirements, the test shall be conducted at the installation site according to the actual operating voltage standard.