csi测量值与DCS相差很大

robently

峰峰值=有效电压值(交流)*1.414*125
看看是不是和DCS一致

hammeryet

如果你通过数据库建立这个缓冲输出的测点，那么你就可以在频谱与波形上看到该频率范围内的振动总量，那么你就可以进行比较了，然后你就可以判断到底是仪器出现问题还是你在采集振动总量时的设置有问题。

[ 本帖最后由 hammeryet 于 2009-5-11 16:02 编辑 ]

stgcgwj

原帖由 jinglongwo 于 2009-5-7 16:00 发表

                               
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bently没有装system1系统，只能比较通频值。
CSI的主要设置如下：传感器类型为DICPLACEMENT
                                      传感器灵敏度为0.00787
                                      测量单位为PK- ...

设置是不是你亲手操作的，会不会有出入？
比较BENTLY和CSI测量信号的频谱，会不会是有丢失？

mriook

bently系统看不到频谱的。
看看波形应该能有些帮助。

fanhxl

轴颈测量面是否有划痕或其他缺陷，造成时域波形有很高的脉冲，CSI 是用RMS值乘以一特定的系数而的到的p-p值（个人判断）。估计在极端的条件下失效。我以前也遇到过此类情况。

wang-yl80

这个问题很有意义，期待楼主解决这个问题，并告知大家

fanhxl

Peak-to-Peak (pp) The difference between the maximum positive-going and negative-going peaks in a
periodic waveform during one complete cycle.
Zero-to-Peak (pk) The pp value of a vibration signal divided by two (pp/2). Also referred to as
“true peak.”
Root Mean Square (RMS) A measurement of the effective energy content in a signal. Mathematically,
the RMS value of a waveform f(t) is defined as
where T is the period (one complete cycle) of the waveform*.

fanhxl

we began an in-depth look
at the answer to a question that arises numerous times
each year from our customers: “I took a vibration reading
with a portable diagnostic instrument, but it does
not agree with what I am seeing on my Bently Nevada™
monitor. Why?”
Customers often assume that there must be a problem
with the monitor, the diagnostic instrument, or both.
However, as explained in part 1 and as repeated here,
this is rarely the case. Instead, there are some very
straightforward reasons why there are often discrepancies
in vibration readings between two instruments
— particularly peak-to-peak amplitude readings.
In our previous article (ORBIT Volume 25, Number 2,
2005), we defined four stages of a signal as it travels
through a vibration measuring instrument. For convenience,
those stages and the corresponding diagram
are repeated below as Figure 1.

fanhxl

Peak-to-peak (pp), zero-to-peak (pk), and RMS are the most commonly used conventions for expressing the
amplitude of vibration waveforms. The conversion between RMS and pk is only equal to 0.707 for a pure sine wave (A). For
a more complex signal (B), the equation of Table 1 must be used to compute the RMS value. The conversion between pp and
pk can differ between manufacturers and becomes apparent if the waveform is asymmetrical (B). When using the Bently
Nevada instrumentation convention of pk = pp/2, the pk value may not be equal to either the positive or negative peaks on an
asymmetrical waveform.