I. Management regulations
According to the GDW 168-2008 "Power Transmission and Transformation State Inspection Test Procedures", infrared temperature measurement is performed on a periodic basis.
Second, the key test object
    The key detection objects include the secondary equipment that should be infra-red detection and the key parts in the secondary circuit.
    TA loop
    (1) Terminal box TA terminal block, protection screen TA terminal block, common fault types: test terminals, loose terminals, rust caused by poor contact caused by heat.
    (2) Measurement and control screen TA terminal, recording screen TA terminal, metering screen TA terminal, common fault type: loose terminals, rust caused by poor contact caused by heat.
    2. DC screen, protection screen, control panel and other DC air switches. Common fault types: Looseness causes poor contact and heat.
    3. Each DC screen, protection screen, control panel fuse
    Common types of faults: poor contact fever.
    4. AC and DC circuit, battery (including communication DC system) DC bus terminal block common fault type: heat.
    5. TV loop
    The voltage level of the station TV common ground point, a circuit breaker or fuse, the common fault types: a small diameter wire grounding or poor contact caused by heat.
    6. secondary circuit and equipment
    (1) Terminal block terminal block, common fault type: poor contact (focus on DC operating circuit).
    (2) Protection device body part: chassis terminal, various plug-ins of protection device, common fault types: poor contact (emphasis on power plug-in and AC plug-in).
    7. Other secondary circuits
    (1) Circuit breaker mechanism energy storage circuit, common fault types: air switch, terminal block loose heating.
    (2) Circuit breaker control box secondary circuit, common fault type: intermediate relay (normal excitation) contact heat.
Third, the requirements of the testing environment
    (1) Requirements for testing environment The equipment to be inspected is a live running device. Under the premise of ensuring the safety of the person and equipment, the coverings that block the infrared radiation, such as glass windows, doors or covers, should be opened.
    (2) The ambient temperature is generally not lower than 5 °C, and the air humidity is generally not more than 85%. It should not be tested in the presence of thunder, rain, fog or snow. The wind speed is generally not more than 0.5m/s. If the wind speed is detected to be significant, the wind speed should be recorded. If necessary, the measurement data should be corrected according to the corresponding formula.
    (3) Outdoor testing should be carried out before sunrise, after sunset or on cloudy days. In the case of infrared detection, the lamp should be turned off, and the device under test should avoid direct or reflection of light.
    (4) Equipment for detecting current heating should be carried out under peak load conditions, generally not less than 30% of the rated load.
Fourth, the detection and diagnosis cycle
    (1) The infrared detection and diagnosis cycle of secondary equipment shall be determined according to factors such as its importance, load rate and environmental conditions.
    (2) Under normal circumstances, the secondary equipment such as the TA secondary circuit, the protective operation power supply air switch terminal, and the DC system should be tested once a year. Important hub stations, substations with harsh operating conditions or aging equipment can shorten the inspection cycle appropriately.
    (3) Secondary equipment after new construction, expansion, alteration or overhaul (especially the circuit modification) shall be subjected to infrared detection and diagnosis within 24 hours after the load.
Five, on-site operation methods
    (1) After the infrared camera is turned on, internal temperature calibration is required, which can be started after the image is stable.
    (2) Infrared detection Generally, all the parts to be tested are scanned with an infrared camera, and the abnormal part of the thermal image is found, and then the temperature measurement is performed on the abnormal part and the key equipment to be tested.
    (3) The radiance of the secondary equipment to be tested is generally 0.78~0.9.
    (4) Under the condition of safe distance guarantee, the infrared instrument should make the equipment under inspection fill the entire field of view.
    (5) Accurate measurement and tracking should set several different angles in advance, determine the best position for detection, and mark it so that the subsequent retest is still at this position, which has mutual compatibility and improves work efficiency.
    (6) Record the relevant parameters according to the characteristics of the equipment to be tested, such as the actual load current, voltage and temperature of the equipment to be tested and the temperature value of the environmental reference body.
Sixth, the diagnostic method and judgment basis of infrared detection
    Surface temperature judgment
     According to the measured temperature value of the surface of the equipment, in accordance with the relevant provisions of GB 763-1990 "Heat of AC high-voltage electrical appliances in long-term work", the temperature exceeding the standard may be based on the degree of equipment exceeding the standard, the load rate of the equipment, the equipment The importance and the amount of mechanical stress the equipment is subjected to determine the nature of the equipment defect, and the equipment that exceeds the temperature at a small load rate or withstands mechanical stress is strictly defined.
    2. Similar comparison method
    In the same electrical circuit, when the three-phase current symmetry and the three-phase (or two-phase) devices are the same, compare the temperature rise values ​​of the corresponding parts of the three-phase or two-phase current-heating type devices to determine whether the device is normal. If the three-phase equipment is abnormal at the same time, it can be compared with similar equipment of the same circuit. When the three-phase load current is asymmetrical, the influence of the load current should be considered.
    For voltage-heating devices of the same model, the device can be judged according to the difference in temperature rise value of the corresponding point. The defect of the voltage-heating type device should be determined by the judgment basis that allows the temperature rise or the same type of allowable temperature difference. Under normal circumstances, when the temperature difference of the same type exceeds 30% of the allowable temperature rise value, it should be regarded as a serious defect. When the three-phase voltage of the operating voltage should be considered inconsistent (the allowable temperature rise allows standard reference temperature rise "charging device Infrared Diagnosis Application Guidelines" in related equipment DL / T 644-1999).
    3. Relative temperature difference judgment method
    For current-induced devices, if the state of the flow-conducting part of the device is found to be abnormal, accurate temperature measurement should be performed, and similar comparisons should be made. For equipment with small load rate and small temperature rise but relatively large temperature difference, if the load rate is changed conditionally, the load current can be increased and then retested to determine the nature of the equipment defect. When the load rate cannot be changed, it can be tentatively set as a general defect and attention should be paid to monitoring.
    Note: should calculate the relative value of the reference temperature difference "charging device Infrared Diagnosis Application Guide" in the formula DL / T 644-1999. When the hot spots of the temperature rise is less than 10K, the device should determine the nature of the defect according to the present method.
    4. Thermal spectrum analysis
    Determine whether the device is normal according to the difference in the thermal spectrum of the same device in the normal state and the abnormal state.
    5. Judgment basis
    (1) Emergency defect (I): secondary equipment surface temperature exceeds 70 ℃, or heating, beyond 30 ℃, or a relative temperature difference exceeds 10 ℃.
    (2) major defects (II): secondary equipment surface temperature exceeds 60 ℃, or temperature exceeds 20 ℃, or a relative temperature difference exceeds 5-10 ℃.
    (3) General thermal defects (III): The surface temperature of the secondary equipment exceeds 50 ° C, or the temperature rise exceeds 10 ° C or the relative temperature difference does not exceed 5 ° C.
    (4) When the temperature rise of the equipment with current heating is less than 10 °C, it should be recorded and strengthened. It is not necessary to determine the nature of the fault. For small loads, pay attention to the heat generation process caused by the load change. Voltage-induced equipment defects are generally identified as major and above defects.
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