35kV voltage transformer
06-21 2025 | By:
35kV voltage transformer-Dry type/epoxy resin casting/indoor/outdoor/ single phase/three phase
1. Definition
35kV voltage transformer (PT) is a measuring device that converts high voltage (35kV) into standard low voltage (such as 100V or 100/√3 V) in proportion, and is used for monitoring, protection and metering of electrical systems. Its core function is to safely isolate high-voltage circuits and provide accurate voltage signals for secondary equipment.
35kv voltage transformer – dry type / epoxy resin casting / indoor / outdoor single phase / three phase
2. Classification
According to the working principle:
Electromagnetic (dry type)
Dry type (epoxy resin casting): oil-free explosion-proof, suitable for indoor or environmentally friendly places.
Capacitive type: realized by the principle of capacitor voltage division, commonly used in ultra-high voltage systems, 35kV is less common.
According to the purpose:
Measurement PT: high accuracy (0.2 level, 0.5 level), used for electric energy metering.
Protection PT: focus on overload capacity (such as 3P, 6P level), used for relay protection.
By structure:
Single-phase/three-phase: 35kV systems are mostly single-phase PTs, and three-phase integrated ones are less common (due to high insulation requirements).
3. Parameter specifications
Rated voltage:
Primary side: 35kV (or 35/√3 kV for phase voltage).
Secondary side: 100V (line voltage) or 100/√3 V (phase voltage).
Accuracy level:
Measurement: 0.2 level (error ±0.2%), 0.5 level.
Protection: 3P level (error ±3%), 6P level.
Rated capacity: 10VA~200VA (select according to load, such as high-precision small capacity for measurement, large capacity for protection).
Insulation level:
Power frequency withstand voltage: 70kV/5min (primary side).
Lightning impulse withstand voltage: 170kV (peak value).
Others:
Transformation ratio: 35000/100V or 35000/√3: 100/√3 V.
Frequency: 50Hz (Chinese standard).
4. Application scenarios
Power system monitoring:
Measurement of 35kV bus voltage in substations and real-time monitoring of system operation status.
Electric energy metering:
Cooperate with electric meters for high-voltage side electric energy settlement (requires 0.2-level PT).
Relay protection:
Provide voltage signals to protection devices (such as low voltage protection, overvoltage protection).
Synchronous control:
In power plants or grid-connected systems, used for synchronization inspection.
Ground fault detection:
Insulation monitoring of neutral point grounding systems (such as PTs with arc suppression coils).
5. Selection points
Environment: Select oil-immersed type (anti-pollution) for outdoor use and dry type for indoor use.
Accuracy: Select 0.2 level for measurement and 3P level for protection.
Capacity: The total power of the secondary load must be less than the rated capacity of the PT.
Special requirements: If ferromagnetic resonance suppression is required, an anti-resonance PT (with a damper) can be selected.
6. Precautions
The secondary side must be reliably grounded to prevent high voltage from entering the low-voltage circuit.
Avoid short circuit on the secondary side, otherwise the PT will be burned.
Regularly check the accuracy and insulation performance to ensure safe operation.
The 35kV voltage transformer is an indispensable equipment in the high-voltage power grid. Its selection and maintenance directly affect the system reliability and data accuracy.
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