1、 Installation and wiring specifications

1. Secondary side anti open circuit
   • During maintenance or repair, it is necessary to ensure that the secondary circuit is always in a closed circuit state. Before removing the secondary side wiring, it is necessary to short-circuit the secondary side first, and then remove the short-circuit wiring after the operation is completed.
   • Install anti open circuit protection devices (such as short-circuit rings) in the secondary circuit. Once there are signs of an open circuit, the protection device can act promptly to avoid generating excessive voltage.
2. Polarity correctness
   • When wiring, it is necessary to strictly check the polarity of the terminals to ensure that the phase of the primary side corresponds to that of the secondary side, in order to prevent measurement errors or protective device malfunctions caused by polarity errors.
3. Fastener inspection
   • Regularly check whether the wiring terminals, bolts, and other fasteners are loose to avoid overheating or discharge caused by poor contact.

2、 Operating environment control

1. temperature management
   • Ensure that the operating temperature of the transformer is below 50 ℃, and heat dissipation measures can be taken in high-temperature environments (such as installing heat sinks or ventilation devices).
   • Small fans can be installed inside the enclosed electrical control cabinet to enhance ventilation and heat dissipation.
2. Moisture and corrosion prevention
   • Use a well sealed casing in a humid environment, place desiccants inside, and regularly check if the desiccants have failed.
   • Choose corrosion-resistant shell materials (such as stainless steel) or apply anti-corrosion coatings to transformers in areas with chemical corrosion risks.
3. Cleaning and maintenance
   • Regularly clean the surface and terminal box of the transformer to prevent the accumulation of dust and dirt from causing a decrease in insulation performance.
   • Check whether the porcelain part is intact, whether there are cracks or discharge marks, and clean the stains in a timely manner to prevent flashover.

3、 Running status monitoring

1. Appearance and sound inspection
   • Visually inspect the transformer casing for any damage, deformation, or oil leakage.
   • Ear check for any abnormal sounds (such as buzzing or discharge sound), which may indicate overheating of the iron core or an open circuit in the secondary circuit.
2. Oil level and quality inspection
   • For oil immersed transformers, regularly check whether the oil level is normal, whether the oil color is clear, and whether there is any oil leakage or seepage.
   • If the oil changes color or contains impurities, it should be replaced or filtered in a timely manner.
3. Load and output monitoring
   • Check the three-phase indication values of the ammeter, prevent overload operation, and ensure that the load is within the rated range.
   • Check if the output current is stable. If there is any abnormal current (such as excessive or fluctuating), it is necessary to investigate alarm signals such as wire breakage and differential current crossing.

4、 Regular verification and testing

1. Comprehensive verification
   • Conduct a comprehensive verification every 3-5 years, including testing of parameters such as transformation ratio, polarity, phase, etc., to ensure that performance meets requirements.
   • When abnormal measurement results are found during operation, immediate verification and troubleshooting are required.
2. Insulation resistance test
   • Regularly test the insulation resistance of the coil (2500V shaker) and the secondary coil (1000V or 2500V shaker), and the non measured phase winding should be grounded.
   • During testing, it is necessary to consider the impact of air humidity and dirt on the surface of the casing on the results. If necessary, shield the casing to eliminate surface leaks.
3. Dielectric loss factor test
   • When abnormal dielectric loss factor (tg δ) is measured during operation, it is necessary to comprehensively analyze the relationship between tg δ, temperature, and voltage. If there is a significant change in TG δ with the increase of test voltage, the operation should be stopped and the reason should be checked.

5、 Fault prevention and handling

1. Iron core overheating prevention
   • To avoid saturation of the iron core caused by long-term overload or open circuit of the secondary circuit, regularly check whether the iron core is clean and free of rust, and ensure smooth oil flow.
   • If overheating of the iron core or odor of insulation material is found, the load should be immediately reduced and the cause investigated.
2. Secondary circuit open circuit treatment
   • Open circuit on the secondary side can generate high voltage, causing discharge sound or spark phenomenon. If power cannot be cut off, insulation tools should be used to reduce the current of the primary load, and the secondary circuit should be short circuited before the open circuit point. After troubleshooting, the short circuit should be removed.
3. Demagnetization inspection
   • The residual magnetism of the transformer core may cause a sudden decrease in current, affecting performance. After high current cut-off or power open circuit, demagnetization treatment is required to restore the magnetic permeability of the iron core.