1. Abnormal Operation and Common Faults of Transformers Piezoelectric Bone Conduction Vibrator,Piezo Ceramic Plated for Bone Conduction,New Design Piezo Bone Conduction Vibrator NINGBO SANCO ELECTRONICS CO., LTD. , https://www.sancobuzzer.com
1.1 Unusual Sounds from the Transformer
Transformers can emit unusual sounds due to various issues. For example, an overload can cause a loud and heavy "clicking" noise. Poor internal contacts or insulation failure may lead to a "hissing" or "crackling" sound near the fault point. During single-phase grounding or resonant overvoltage in the grid, the transformer may produce a sharp sound. Loose components, such as unsecured core screws or missing parts on the core, can result in uneven "noises" or "hammering" sounds. Additionally, when a large power plant starts up, significant load changes can increase the transformer's noise level.
1.2 Rise in Oil Temperature Under Normal Load and Cooling Conditions
Even under normal conditions, an increase in oil temperature can indicate underlying problems. Local short circuits in windings, internal contact faults, increased resistance at connections, or large resistance shorts on the secondary side can all raise the oil temperature. Eddy currents or damaged core clamping screws can also cause overheating. If the insulation between the core screw and silicon steel sheets is compromised, a large current may flow through the screw, leading to increased oil temperature.
1.3 Oil Injection in the Oil Pillow or Explosion Vent
If the secondary system experiences a sudden short circuit and protection fails, or if there is an internal fault with blocked vents, high heat can cause the transformer oil to suddenly eject. This may lower the oil level and trigger gas protection.
1.4 Three-Phase Voltage Imbalance
Voltage imbalance can occur due to several reasons. Uneven three-phase loads can shift the neutral point, causing imbalance. Ferromagnetic resonance in the system can also lead to this issue. Additionally, local winding faults between turns or layers may result in three-phase voltage imbalance.
1.5 Relay Protection Activation
Relay protection typically indicates an internal fault. Gas protection is the main safeguard for transformers. It can detect some internal issues. When light gas trips first, followed by heavy gas, it usually signals a serious problem. If no external damage is found, the type of gas in the relay should be checked. Non-flammable, colorless, odorless gas with high oxygen content and stable oil flash point suggests air has entered the relay. In such cases, the transformer can continue operating. However, flammable gas indicates an internal fault that needs further analysis using gas chromatography to identify the root cause.
1.6 Flashover and Explosion of Insulated Porcelain Bushings
Poor sealing, improper installation, or moisture ingress can damage the insulation of bushings. Internal discharge due to gaps in the capacitive layer or severe surface scaling and cracks on the bushing can lead to flashover or explosion.
2. Causes of Transformer Failure
Transformer failures are generally categorized into electrical and magnetic circuit issues. Electrical faults include coil insulation degradation, moisture, poor switch contact, and overvoltage caused by secondary system short circuits. Magnetic circuit faults involve the core, yoke, and clamps, such as shorted silicon steel sheets, insulation damage between core screws and clamps, or discharge from poor grounding.
3. Preventing Transformer Failures During Operation
Monitoring the transformer’s current, voltage, and temperature is crucial. Overloaded transformers should be inspected more frequently. Regular checks should be conducted according to schedule, especially after installation or maintenance. Transformers that are overloaded require thorough inspections.
3.1 Routine Inspection Items
Check if the transformer produces normal sounds and listen for any abnormal noises. Ensure the oil level and color in the oil tank and bushings are correct, with no leaks. Monitor oil temperature and ensure the thermometer readings match. Check the bushings for cleanliness, cracks, or discharge marks. Examine the lead wires and cables for discoloration or other issues. Confirm that cooling systems operate correctly, with no strange noises. Ensure the pressure release device and safety vent are intact. The gas relay should have no gas, and seals must be tight. The respirator should be dry, and the grounding connection should be secure. Control boxes and terminal boxes should be closed and free from dampness.
3.2 Special Inspection Items
After thunderstorms, check for discharge traces, overheated joints, and arrester counter readings. On windy days, inspect for swinging leads and debris around the transformer. During snowfall, look for melting ice at joints and possible ice slippage. On foggy days, check for spark discharges or pollution flashovers. When temperatures change rapidly, monitor oil levels, temperature, and cooling system performance. During overloads, check for temperature changes, good contact at joints, and proper operation of the cooling system.