Interested to Buy Any Domain ? << Click Here >> for more details...
why we use -ve voltage in vibration monitoring
system.generally we use 4 to 20 mA as output of instrument
then why we use voltage in vibration
- 2 Answers
- 9379 Views
- I also Faced
- E-Mail Answers
Answer Posted / dondapati ramesh
For High speed rotating equipment only,we are using this
negative voltage for vibration sensor.This negative voltage
is always set as gap voltage between the sensor and surface
of the rotating equipment.
This gap voltage is always set as -10Vdc.
This because of Ratio frequency, which is created by the
controller of vibration sensor. These frequencies are
generated under negative voltage only. which is also varies
with respect to eddy current flow. The amplitude of this
ratio frequency is measured as vibration.
For your information, Noice level is very less in negative
voltage compare than positive voltage which will not affect
the sensitive range of measurement of vibration.
For your information:-This concept is used in Bently neveda
vibration monitoring system.
The principle is that analyzer supplies a negative voltage
to transducer, who converts it into a frequency & sends it
across the probe. Now as the probe comes into the area of
rotor it creates a magnetic field & with it eddy current is
produced on the rotor side. This changes the amplitude of
the frequency. It induces the voltage & remaining frequency
comes to the transducer through the return way. Transducer
converts it into the voltage.
Now coming back to the question The gap voltage has a
negative relation with the voltage induced i.e. as the gap
increases the induced voltage decreases. So to make it to
into a linear relationship, negative voltage is supplied.
i.e
Gap Gap voltage
0 mm 0 vtg
1 mm -9 voltage
2 mm 18 voltage
& when the probe is in air it will have no induced voltage
so all -24 voltage without induced voltage will return back.
| Is This Answer Correct ? | 9 Yes | 0 No |
Post New Answer View All Answers
what happen if i increase height of displacer type LT.accuracy or sensitivity are affected.why?
tell me the field & lab calibration procedure step by step with diagram of pressure gauge, pressure switch, pressure transmitter, temperature switch, level switch, flow switch, flow transmitter, temperature transmitter, temperature indicator, flow indicator, level indicator, control valve, thermocouple, pressure indicator (digital & analogue),
in natural gas indirect water bath heater,how to prevent the problem of backfire from firetube during ignition...becoz of this backfire performance of wbh is going low.
In control valve proximity inductive sensor is taken as digital feedback for full open and full close.Normally its volts 24v when the sensor acts the feed back voltage 14v so that our relay not indicating in plc panel . kindly give the solution.
how can use ram
In apron feeder how TPH is calculated?
Describe the function of Accumulator into the Pump
Can anybody tell me how to select the size of earthing cable for DCS & PLC system.Please tell me any relevant answer here or mail it to me.
Draw a great bridge circuit.
how do we commission inergen system?
What is hp & mp seperator .& what is its working principle ?
1.what is the effect of vapour presuure in orifice plate flow measurement 2.which is more effective 2 pressure sensors or one single differential pressure sensor in orifice plate measurement 3.how to design a v/i converter and i/v converter 4.how many type of thermocouple are there 5.how many leads are there in thermocouple measurement 6.how pressure sensors are connected in level measurement in differential pressure method 7.what is the output of capacitive pressure sensor (ac or dc),how its o/p is signal charactarized 8.what is the physical meaning of discharge coeeficient,why it is calculated,orifice plate what is its value,why it is less than 1,Q at upstream is equal to or not equal to Q at downstream of orifice plate why?what is vena contracta in orifice plate 9.why rotameter is called variable area flowmeter,it can measure flow even if area is not varying,why it is made tapered 10.design a 10 bit counter ,which counter you will prefer 11.how to remove self heating error in RTD 12.which is more sensitive pt100 or pt50 13.why thermocouple are connected in parallel 14.what is lead contact error in RTD,how to avoid 15.what is P,PI,PID,PD controller,why there is no ID controller 16.what is override,split range,sequential,ratio,feedforward,cascade controller 17.why we moved from SR to JK and then JK to master slave JK flipflop,give correct reason 18.how to measure level of a closed container which contains vapour and liquid,remember no vapour gas should be leaked,so ultrasonic and capacitive is not an option,design another method 19.how to design horse race counter including sensors and signal conditioning element 20.what is bevelling
explain key exchanges in all security modes WPA,WPA2,TLS?
State some of balance principle’ advantages?
Whether the DI, DOs shields can be connected with Analog Input Shield Earthpit?
