An AC Electromagnetic Flowmeter Refers To An Electromagnetic Flowmeter
An AC electromagnetic flowmeter refers to an electromagnetic flowmeter that excites the excitation coil with industrial frequency (50Hz or 60Hz) sinusoidal alternating current.
Core technologies
Comparison with Modern Mainstream Excitation Techniques
| Characteristics | 50/60Hz AC Electromagnetic Flowmeter | Modern Low-Frequency Rectangular Wave Excitation Flowmeter |
|---|---|---|
| Excitation Waveform | 50/60Hz Sine Wave | 1/8, 1/16 of power frequency and other low-frequency rectangular waves (e.g., 6.25Hz) |
| Core Issues | Severe orthogonality interference, unstable zero point. | Orthogonality interference is fundamentally avoided. Sampling is done during the stable DC period of the magnetic field, with no dΦ/dt. |
| Zero Point Stability | Poor, frequent manual zero adjustment is required. | Excellent, intelligent transmitters can automatically track and correct the zero point. |
| Power Consumption | High, coils tend to heat up. | Low, pulse excitation is used, which is energy-saving and results in less coil temperature rise. |
| Resistance to Power Frequency Interference | Poor, susceptible to interference at the same frequency. | Strong, sampling frequency avoids power frequency and its harmonics. |
| Current Status | Has been largely phased out and only exists in extremely old devices. | Definitely the market mainstream, accounting for over 95% of applications. |
The AC electromagnetic flowmeter is a great transitional technology that solved the problem from 0 to 1, but due to inherent defects, it failed to achieve optimization from 1 to 100. It marked the turning point of the electromagnetic flowmeter technology from the exploration period to the mature period. Its historical lessons directly pointed out the development direction of modern electromagnetic flowmeters - low frequency, digitalization and intelligence.