What are the common types of voltage sensors?

Voltage sensors can be classified by polarity into DC voltage sensors and AC voltage sensors, by output signal into analog output voltage sensors and digital output voltage sensors, and by measurement principle into resistive voltage dividers, capacitive voltage dividers, electromagnetic voltage transformers, capacitive voltage transformers, Hall voltage sensors, etc.

1. Electromagnetic Voltage Transformer

Its principle is similar to that of a transformer, achieving isolated measurement of the primary voltage, but it is large in size, has a narrow frequency band, and is generally only suitable for measuring at power frequency or other rated frequencies. It also has issues such as resonance and output short-circuiting.

2. Hall Voltage Sensor

Its basic principle is that the primary voltage is limited to a milliampere level through an external or internal resistor. This current passes through multiple turns of a winding, and the magnetic field generated by the primary current is detected by a Hall element in the air gap, inducing a corresponding electromotive force. This electromotive force is adjusted by a circuit and fed back to the compensation coil for compensation. The magnetic flux generated by the compensation coil is equal in magnitude and opposite in direction to the magnetic flux generated by the primary current, thus maintaining zero magnetic flux in the magnetic core. Hall voltage sensors are small in size, have good linearity, and short response times, but have a narrow testing bandwidth and lower measurement accuracy.

3. Voltage Divider Sensor

Divided into resistive voltage dividers and capacitive voltage dividers, which directly convert the primary voltage into a low voltage signal usable by measuring instruments. The resistive voltage divider outperforms the capacitive type due to the absence of resonance issues. Voltage divider sensors are simple to measure and have relatively high measurement accuracy, but the voltage divider resistors require stable temperature characteristics, low error, and high voltage resistance. Additionally, there is no isolation between the high voltage side and the low voltage side, posing safety risks.

4. Fiber Optic Voltage Sensor

Based on the electro-optic effect, light passing through certain materials under the influence of an electric field or voltage undergoes birefringence, and the phase difference between the refracted light waves is proportional to the applied voltage. The measurement of external voltage is achieved by detecting the phase difference of the light waves using a phase detector.

5. Resistive Voltage Divider

The voltage divider is a specialized instrument for field measurement, suitable for measuring DC high voltage and AC high voltage. The voltage divider uses a balanced equipotential shielding structure, employing high-quality electronic components inside a completely sealed insulating tube, making the entire device accurate in testing, good in linearity, stable in performance, reasonable in structure, easy to carry, simple to operate, and intuitive in display, thus making it an ideal instrument for field measurement.