• Zhejiang Jinwei Electric Co., Ltd

Analysis of the Impact of Medium-mounted Structure on the Operational Stability of Potential Transformers (PTs)

1. Introduction

2. Mechanical Influence on PT Operational Stability

2.1 Vibration and Shock Resistance

• Fixed and Moving Components: In a medium - mounted structure, PTs are often installed on a draw - out cart or within a compartment with mechanical components for insertion, extraction, and locking. During the movement of the cart (such as during switching operations or maintenance), vibrations and shocks may occur. If the PT is not properly fixed or cushioned, these mechanical disturbances can cause internal component loosening, such as winding displacement or terminal connection looseness in the PT. This can lead to abnormal electrical performance and reduced operational stability.

• Interlocking and Guide Mechanisms: The interlocking and guide mechanisms of the medium - mounted structure play a crucial role. Well - designed interlocking systems ensure that the PT is in the correct position during operation, preventing misalignment that could cause mechanical stress on the PT. High - precision guide rails can reduce lateral forces during the movement of the PT - mounted cart, minimizing the risk of mechanical damage to the PT.

2.2 Structural Support and Load - bearing Capacity

• Mounting Design: The medium - mounted structure's mounting design for PTs determines the load - bearing capacity and support stability. A sturdy mounting plate or frame with appropriate dimensions and materials can evenly distribute the weight of the PT, reducing the risk of deformation under its own weight or external forces. In contrast, a weak or improper mounting design may cause the PT to tilt or sag over time, affecting the magnetic field distribution inside the PT and leading to measurement errors and potential insulation problems.

• Earthquake - resistance Considerations: In regions prone to earthquakes, the medium - mounted structure's seismic performance directly impacts PT stability. Structures with enhanced seismic - resistant designs, such as anti - seismic fasteners, shock - absorbing pads, and reinforced frames, can better protect PTs from damage during seismic events, ensuring continuous and stable operation.

3. Electrical Influence on PT Operational Stability

3.1 Insulation Performance

• Clearance and Creepage Distance: The medium - mounted structure defines the spatial arrangement of PTs within the switchgear. Adequate electrical clearance and creepage distance must be maintained between the PT's live parts, other electrical components, and the grounded enclosure. In a well - designed medium - mounted structure, proper insulation partitions and spacing are ensured, reducing the risk of electrical breakdown due to flashovers or surface discharges. Conversely, insufficient clearance or creepage distance, which may be caused by a cramped or poorly designed structure, can lead to insulation failure and instability of the PT operation.

• Environmental Protection: The enclosure of the medium - mounted structure serves as a barrier against environmental factors that can affect insulation. A sealed and dust - proof structure can prevent the ingress of moisture, dust, and corrosive gases, which are harmful to the insulation materials of PTs. Moisture, for example, can reduce the insulation resistance of PTs, while dust accumulation may cause surface tracking and electrical leakage, ultimately endangering the operational stability of PTs.

3.2 Electromagnetic Interference (EMI) and Crosstalk

• Component Arrangement: The layout of components within the medium - mounted structure can generate electromagnetic fields that may interfere with the operation of PTs. For instance, nearby high - current conductors or power - electronic devices can produce strong electromagnetic fields. If the PT is not shielded or properly positioned, these fields can induce unwanted voltages in the PT windings, causing measurement errors. Additionally, crosstalk between different PTs or between PTs and other electrical components in the same structure can also occur, affecting the accuracy and stability of voltage measurement.

• Shielding and Grounding Design: An effective medium - mounted structure should incorporate proper shielding and grounding measures. Magnetic shielding materials can be used around PTs to reduce the impact of external electromagnetic fields. A reliable grounding system can quickly dissipate induced charges and electromagnetic interference, minimizing the influence on PT operation. Without these design considerations, the PT's performance may be severely degraded, leading to operational instability.

4. Environmental Influence on PT Operational Stability

4.1 Temperature and Humidity Control

• Heat Dissipation: PTs generate heat during operation due to winding losses and core losses. The medium - mounted structure's ventilation and heat - dissipation design are critical for maintaining the PT's operating temperature within an acceptable range. A structure with sufficient ventilation holes, cooling channels, or forced - air - cooling systems can effectively remove heat, preventing overheating of the PT. Overheating can accelerate the aging of insulation materials, reduce the PT's accuracy, and even cause permanent damage, thus affecting its stability.

• Humidity Regulation: As mentioned, the enclosure of the medium - mounted structure plays a role in humidity control. In high - humidity environments, a structure with good sealing and dehumidification functions (such as desiccant installation or built - in dehumidifiers) can protect PTs from moisture - related problems. Excessive humidity can lead to insulation degradation, mold growth on insulation surfaces, and increased leakage currents, all of which pose threats to the stable operation of PTs.

4.2 Dust and Pollutant Prevention

• Sealing Performance: In industrial or polluted environments, dust, dirt, and corrosive pollutants are common. A medium - mounted structure with high - quality sealing gaskets, doors, and covers can prevent these substances from entering the PT compartment. Once inside, dust can accumulate on the PT's insulation surfaces, reducing insulation performance, while corrosive pollutants can chemically attack the PT's metal parts and insulation materials, weakening the overall structure and stability of the PT.

5. Conclusion