PLUS+1 User Forum

PLUS+1 Hardware => Controllers => Topic started by: pinias on September 04, 2014, 10:47:44 PM

Title: pressure tranducers
Post by: pinias on September 04, 2014, 10:47:44 PM
where is the pressure transducers section?

I got a system with about 20 pressure tranducers, so sometimes one of them fails, the problem is the way it fails.

it suddenly start giving bad readings, for instance when I should see 0 PSI it is reading 2000 or so, then when I run my system the pressures gets incremented as I apply load. The failed pressure increases its readings up to its maximum range then it goes back to 1000 or so.

so no any fault is been detected by the controller/function block. After some hours the readings from the tranducer are just 0 (no matter what pressure is in my system) and the function blocks says none fault is present.   

that means the input voltaje is not too low or too high and that is the problem, the fault for the transducer is based on that.

I wonder to know if someone has a different technique to know when the transducer is gotten bad.

or any other advise is welcome



Title: Re: pressure tranducers
Post by: FluidPowerTom on September 10, 2014, 06:55:42 PM
I suspect the only way to be 100% sure to detect a failure is to add a redundant transducer or at least a pressure switch.

If you've got a solenoid valve that vents the system pressure you could implement some logic where if the pressure is vented but the transducer still sees 1000 psi or so then that may indicate a failure.  Also if you're running with no load and know the system pressure should be low like a few hundred psi then that could trigger a fault if the transducer is reporting 2000 psi.  I think the best you'll be able to do without a redundant sensor is to find some conditions that could trigger a fault.

If you use one of those methods to trigger a fault which indicates a potential failure then you might add in a logic sequence to somehow test the transducer.  This could mean ramping up the pressure, and if it sees something weird like the pressure go from 2000+ psi to 1000 psi when you know the load is increasing then you've got a failure.
Title: Re: pressure tranducers
Post by: oiltronic on September 16, 2014, 08:06:53 AM
I agree with FluidPowerTom.  Try to detect situations that don't make sense, even if the pressure sensor output seems without fault.

And if this is happening often, something might be mechanically wrecking the sensors with hydraulic shock loads greater than their rating.
Title: Re: pressure tranducers
Post by: pinias on November 24, 2014, 06:03:36 PM
well, I appreciate your suggestions but,

in a system with 20 sensors , installing redundant sensors makes it more complex and more espensive.

according with the datasheet the sensors come with a pulse snubber built in which would fix the issue of a mechanical faluire due to hammer hydraulic back pressure,

So what I have done is added a mechanical pulse snubber at the sensor port input, so far it seems to be helping I have no longer sensor faliures.

thanks for yours suggestions