# Mark-5 Vibration Transducers

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Thread Starter

#### shyam

Dear all,

We are using Frame-6 gas turbine with mark-V control system. For this we are using Bentley Nevada radial vibration probes and axial displacement probes with 3300 proximitor. proximitor output is connected to Mark-V control system, mean there is no separate Bentley Nevada panel is there. For major overhauling purpose we removed all the probes. My question is for fixing back the radial vibration probes how much gap voltage we need to set? is it -10 V or else? also how can I set Axial displacement probes with correct gap voltage because rotor is going to install after overhauling?

Can anybody help?
Thanks...

#### joe45678

We set ours to where the "0" is in the middle of the shaft travel.

To set thrust where the middle of the thrust is "0".
1. Thrust shaft toward probe

2. Set probe to -10VDC (Bently 0)

3. Thrust shaft away from probe

4. Take total traveled voltage and divide by 2. (ex. -5volts travel/2=-2.5volts)

5. Add step 4 to step 2. (ex. (-2.5) + (-10) = -12.5VDC)

6. Set probe to voltage in step 5. (-12.5VDC)

This will get you close. thrust both ways a couple of times and make any small adjustments as necessary.

Below is not how we set ours, but I believe is a better method.

Set the probe to be at 0 when the shaft is resting on the active shoe. This will tell you:
1. How far off the active shoe the shaft is (-)

2. If the shaft is pushing into to the active shoe and how far. (+)

To set the shaft where 0 is riding on the active shoe:
1. Thrust the shaft toward the active shoe

2. Adjust the probe until the Bently display reads 0 mils (close to -10VDC).

Anyone have any other ways they setup their probes?

Anyone setup their probes where 0 is riding in the active position?

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#### shyam

Thanks for your reply, for radial probes can we set -10V gap voltage, Am I right?

#### joe45678

Yes, that is correct.

We set our radial probes up at -10VDC. If you get them within .2VDC should be good.

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