What is the purpose of connecting a resistor in parallel with the speed sensor?
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The unit is equipped with a Hangyang steam turbine, and there are 5 speed sensors on site. During operation, the acceleration curves of 3 of these speed sensors were consistent, while those of 2 sensors deviated significantly at certain points. This kind of problem has not occurred before during operations; we checked the installation locations of the speed sensors as well as the surrounding environment, and nothing seems to have changed. We don’t know why this is happening After contacting the technicians at Hangyang Oxygen, a 320-ohm resistor was connected in parallel to the wiring of the control system, and thereafter the acceleration curves of the five speed signals became basically identical. What is the principle of parallel resistors? What is its function? I would appreciate it if someone who knows the answer could give me some guidance.
Filtering effect. Eliminate clutter interference.
That’s a good question. Is there anyone knowledgeable who can explain it?； Why parallel resistors? And it’s 320Ω
As for why it is 320 ohms specifically, I think the manufacturer’s technical staff should know better
The speed detection card has requirements regarding the input impedance of the sensor; the parallel resistor is used to adjust this input impedance, right?
Correct answer: victory:
Correct answer: victory:
To measure rotational speed, a magnetoelectric probe is generally used; it outputs a frequency signal, with a voltage value such as 4V for AC. A resistor connected in parallel with the probe, such as 100 ohms, generally does not affect the rotation speed, unless the value of this parallel resistor is low, such as 10 ohms or less (depending on the sensitivity of the tachometer). Different frequencies indeed result in different output voltage values, but it is not possible to determine the rotation speed by measuring the voltage; this method is inaccurate and unreliable. The manufacturer’s parallel resistor is likely located in the tachometer amplification circuit; this is feasible as it allows for a proportional and linear adjustment of the speed, and I have done this as well. Eddy current speed measurement is another principle; it is not used very often. A dedicated transmitter is required, but the principle is similar – it also relies on differences in pulses.