Greeting all,
We have BN vibration sensors 4-20 MA
There is issue with the reading some times become spikes and trip the motor
These observed only when start the moter but when tge motor off the reading stable.
We repkace the sensor with new cable but the same issue
The third try we replave the terminal for JUNCTION BOX , We will see what will happen when motor start.
I want know what is the reason for this issue
And how we prevent this problem to hapoen again.

 

Sensor model?
This generally happens due to the integration from acceleration to velocity and corresponding amplification in the internal electronics of the transducer. In time waveform, acceleration and velocity are always 90 degree phase shifted. The problem is called ski-slope problem.
Try to change the sensor, else fix the sensor when the motor has attained some speed(works sometimes although not recommended lol).

 

It's probably pretty simple. Someone ran the low-level signal wiring/cabling in the same conduit, cable trench, cable tray as the motor leads, or in a cable trench/tray or conduit that is too close to the motor leads.

The other problem--which could also be contributing to the issue--is the shield drain wire (presuming twisted, shielded wiring/cables were used to connect the sensors to the monitor). THE SHIELD DRAIN WIRES SHOULD BE CONNECTED TO GROUND AT ONE END ONLY--and by convention that is at the monitor end of the interconnecting wiring/cabling. Connecting the shield drain wires at both ends results in a path for induced voltages from high-voltage and/or high current wires/cables in proximity to the low-level wiring cabling to circulate, thereby negating the use of shielding and drain wires.

There are conventions and standards about running low-level (4-20 mA) wiring/cabling in a secure distance from high-level cabling in conduits, cable trays and -trenches. It's convenient to run all cables (high-level and low-level) in the same conduits, cable trenches or -trays--but it just causes exactly this kind of trouble. Combine this bad practice with incorrectly terminating shield drain wires of low-level cables and you have the perfect recipe for trouble exactly like you are describing.

It could be something more nefarious, certainly, but best to start with the simple things and not overlook them.

 

Sensor model BENTLY NEVADA 177230-01-01-5
The sensor was replaced with new one also the cable replaced
And the issue same.

 

Talal9001...
1. Welcome to Control.Com
2. What is the specific application on the motor?
3. Is it a first-time problem, that is, a start-up issue?
4. Has the problem persisted for a while in an operating facility?
5. If any, what is the Voting-Mode?
6. If any, what has a Vibration Instrument revealed?
Happy Holidays,
Phil Corso ([email protected])

 

Talal9001...
1. Welcome to Control.Com
2. What is the specific application on the motor?
3. Is it a first-time problem, that is, a start-up issue?
4. Has the problem persisted for a while in an operating facility?
5. If any, what is the Voting-Mode?
6. If any, what has a Vibration Instrument revealed?
Happy Holidays,
Phil Corso ([email protected])

This is for High presure motor for Ro
The problem observed during the start up of motor and the reading fluctuating until the motor trip take around 10 MIN

 

Is any one used another manufacture of BN 4-20 ma vibration sensor.
I am planning to replace it to another type.
Realy BN make us on truble and can not trust on vibration.

 

If your wiring is not correct ANY 4-20 mA sensor is going to give you similar results.

And only B-N sells B-N equipment (under the B-N name). A LOT of other companies sell 4-20 mA vibration sensors.

Blessed day!

 

AND, you didn't answer Mr. Corso's Question 6. If you've used another vibration instrument to measure machine vibration during start-up and loading what has it revealed about the actual vibration? Is it high, higher than expected, normal? WHAT???

In other words, do you know (through testing and verification) if you have a true vibration problem or not?

More blessed days!

 

Hi all
Realy this problem strange for us.
No actual high vibration observed during pump running.
We replace 3 sensors of BN and same issue.
The last time i replaced to another manufacture and the sensor is working fine without any huntting.
We do not know if these sensor are malfunction or defectives cuz these are new.
This is the story.
We do not know is BN very sensetive for any noise or interferances .

 

I have anothe Q
If the sensor range 0- 20 mm/s
And DCS configuration is 0-15 mm/s
How to know the corrct reading in DCS?

 

WOW

 

Simply WOW!!!

 

What?