I. Objectives of the Test
The formulation of the on-site test plan should prioritize clearly defining the test objectives, which will standardize the subsequent parameter setting and process design, ensuring the test is accurate and effective. The types and core purposes of on-site routine tests are as follows:
1. Current Load Test: Verify the current-carrying performance of electrical equipment under rated current or overload current conditions, and simultaneously check whether the action characteristics of the accompanying protection devices comply with the standard requirements.
2. Temperature Rise Test: Detect the temperature rise of each core component of the equipment under the specified current for a continuous period, and confirm that the temperature rise values of the equipment comply with the long-term working temperature limit specifications of insulating materials and conductors.
3. Current Transformer (CT) Calibration: Verify the transformation ratio accuracy, wiring polarity, and volt-ampere characteristics of the current transformer to ensure the normal metering and protection functions of the equipment.
II. Procedural Basis
All on-site test operations must strictly follow the power safety work procedures and official testing standards. The core execution basis is as follows:
1. “Electric Power Safety Work Procedures (Electrical Part of Power Plants and Substations)”
2. DL/T 596 “Preventive Test Procedures for Power Equipment”
3. GB/T 16927.4 “High Voltage Test Technology – Part 4: Measurement System for Test Current and Test Voltage”
III. Requirements for Selecting High Current Generator
Based on the on-site test conditions, current parameters, and test duration, the following selection principles should be followed:
1. Structural Selection: When the test current is below 2000A, an integrated structure device can be selected, suitable for flexible and mobile on-site operation scenarios; when the test current is above 4000A, a split structure device should be preferred, consisting of a control console and an up-conversion unit, which is convenient for on-site layout and configuration, and can enhance the equipment’s heat dissipation effect.
2. Operating Condition Selection: Most conventional equipment is suitable for short-term and intermittent test conditions. If long-term temperature rise tests are required, it is necessary to select a model clearly marked as supporting long-term operation to avoid equipment overload damage.
IV. Requirements for On-site Wiring
To ensure the stability of the test and avoid wiring faults risks, on-site wiring must strictly meet the following specifications:
1. Wire Cross-sectional Area Requirements: The connecting wires from the secondary of the up-conversion unit to the tested equipment should ensure sufficient cross-sectional area, and the selection can be calculated based on the current density standard of 6-8A/mm². At the same time, the length of the wire laying should be shortened as much as possible to effectively reduce line voltage drop and reduce wire overheating problems.
2. Contact Surface Treatment Requirements: The contact surfaces of all connection terminals should be polished with fine sandpaper to expose the metal luster completely, and then firmly fastened the connection. This can minimize contact resistance to the greatest extent. Poor connection is the core cause of the test current not reaching the rated value and local overheating and burnout of the equipment, and it needs to be carefully controlled.
3. Protection Grounding Requirements: The metal enclosures of the test equipment, including the control console and up-conversion unit, must be reliably grounded using dedicated grounding wires, and the grounding resistance must comply with industry standard specifications to ensure the safety of the test operation.
V. Standardized Operating Procedures
The entire on-site test process strictly implements the safety operation system of “one person operating, one person supervising”. The standardized operation steps are as follows:
(1) Pre-test Inspection
1. Insulation Check: For newly installed equipment or equipment that has been idle for a long time, before the operation, use an ohmmeter to detect the insulation resistance between the windings and to ground of the equipment. The insulation resistance value must not be lower than 0.5 megohms.
2. Power Supply Capacity Verification: Verify the on-site power supply capacity in advance to ensure it meets the rated input requirements of the test equipment, to prevent problems such as line overheating and voltage drop caused by insufficient power supply capacity, which may affect the normal conduct of the test.
3. Voltage Regulator Zero Position Check: Confirm that the voltage regulator rotates counterclockwise to the bottom zero position, and the zero position indicator light of the equipment is normally illuminated, ensuring the initial state of the equipment is safe and compliant. 4. Range selection: Based on the output current size of the test target, precisely switch the current conversion switch to the corresponding large or small range. It is strictly prohibited to place the switch in the middle position, as this may cause a high-voltage hazard due to the open circuit of the secondary side of the current transformer.
(II) Startup and current increase
1. Close the equipment power air switch to confirm that the equipment power indicator light is normally illuminated and the equipment is powered on normally.
2. Equipment startup: Press the green start button of the equipment to make it enter the state of waiting for current increase.
3. Uniform current increase: Rotate the control handle of the voltage regulator clockwise slowly and evenly. Continuously observe the current meter value throughout the process. Do not adjust the handle rapidly or significantly to prevent surge current from damaging the tested equipment.
(III) Process monitoring
1. Current stability control: During the test process, if the test current deviates due to voltage fluctuations in the power grid, adjust the parameters of the voltage regulator slightly to maintain the rated test current stable.
2. Temperature monitoring and record: During the temperature rise test, after the current stabilizes, regularly check the heating status of the equipment body, connecting wires, and connection points. At the same time, make data records.
3. Equipment status inspection: During the entire test process, continuously inspect the operating status of the equipment. If any abnormal signs such as abnormal noise, odor, or smoke are detected, immediately stop the operation to investigate the problem.
(IV) Power-off and reset
1. After the test operation is completed, slowly rotate the control handle of the voltage regulator counterclockwise to set the equipment parameters to zero.
2. Press the red stop button of the equipment to terminate the equipment operation.
3. Disconnect the power air switch to completely cut off the main power supply of the equipment.
4. Remove the test wiring and grounding lines in a standardized sequence, and organize and store the test equipment and tools.
Six. Safety guidelines and risk prevention
(1) Work limit requirements: The test equipment is designed for short-term operation. It is strictly prohibited to operate it for a long time at the rated capacity. Exceeding the rated current for operation is also forbidden. To avoid overheating and burning of the equipment or damage to components.
When conducting continuous temperature rise tests, sufficient and qualified fire-fighting equipment must be available at the test site. A dedicated person must be assigned to stand by throughout the process. The person on duty must not leave their post or be absent from their post at will.
(2) Emergency handling procedures
If any emergency situation such as smoke, abnormal odor, abnormal sound, or sudden fluctuation of the current is detected during the test, the operator must cut off the main power supply of the equipment immediately. Conduct a comprehensive fault investigation and wait until the potential hazards are completely eliminated and the equipment status is normal before restarting the test operation.
(3) On-site environment management
1. The test operation site must not store any flammable or explosive debris. The operation area must be kept clean and safe.
2. The test equipment must be stored in a clean, ventilated, and dry indoor environment. Before conducting tests in high-altitude or high-humidity special working conditions, strictly consult the equipment manual and adjust the operation parameters according to the environmental conditions to adapt to the on-site conditions.
Post time: Jul-17-2026