Difference between 25-card and 50-card versions of Bentley 3500 system
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The 25-card and 50-card versions of the Bentley 3500 system seem to be cards used for measuring rotational speed; on our side, the rotational speed of chemical compression units is measured using the 25-card version, while power plant turbines use the 50-card version for this purpose. Could Kuanyou please explain the difference between 25 cards and 50 cards? And what is the difference between the probes for the two types of cards on-site? I hope an experienced expert can help explain this. The attachment contains a selection manual for the cards for everyone’s reference. Thank you
25 is the phase angle, and 50 is the rotational speed. The 25 model does not have a 4-20Ma analog output, while the 50 model does. Even when they measure the rotational speed, it is not used for control or overspeed protection interlocks, but rather as a basis for determining zero rotational speed
What is the fundamental difference among the terms phase angle, rotational speed, and zero rotational speed? Also, what is used for the overspeed protection interlock? Is it something using a flying hammer? Please give me some advice. Thank you
A flying hammer is a physical interlock, while overspeed protection is a soft interlock; generally, electromagnetic valves are used for control. The associated cabinet can be included as well, or it can be built on one’s own
Could you explain the differences between phase angle, rotational speed, and zero rotational speed? Thank you
Isn’t the overspeed protection implemented using Woodward ProTech 203? Three speeds are fed into 203, which outputs a digital signal when overspeed occurs; I’m not familiar with anything else
Key phase measurement involves placing a groove on the shaft under test, known as a key phase mark. When this groove moves to the probe position, it results in a sudden change in the distance between the probe and the surface being measured; the sensor then generates a pulse. One pulse is produced for each full rotation of the shaft, and the timing of these pulses indicates the position of the shaft during each rotation cycle. 0 speed is the shutdown speed
What’s the use of 0 rotation speed? Is zero rotation just the single value of “0”? I heard from an experienced master before; it seems it’s not like that”