Entity Parameters

"Entity parameters"? What have you been smokin'?

Then stop working on it and get some proper training.

I have never heard the term 'entity parameters' either.
It sound like someone is adding random words to make an already compelx subject even more baffling.
In future I shall call bread 'an entity foodsuff of the wheat based variety', I'm sure that will simplify my purchasing experience.
Drop the word 'entity' it is meaningless hogwash in my inflated opinion tautology.

Unless you can find a compelling distinction between entity and parameter in that context?
They are not even parameters of an entity, they are parameters which depend on external conditions.
Del

Quite simply, the cable will store sufficient energy to make an incendive spark, which is exactly not what is wanted in an intrinsically safe circuit wandering into potentially explosive atmosphere. The circuit becomes intrinsically unsafe and the effect could be devastating...

http://en.wikipedia.org/wiki/Intrinsic_safety

I am still not clear abt it.

Capacitance / Inductance is higher on Transmitter+Cable side.

So when this is connected to Barrier with lower values ,What effect it will have on barrier?

None on the barrier.

Everything on the spark that is generated when something happens in the hazardous area, because the cable is storing too much energy.

Do not attempt to install, test or modify electrical circuits in potentially explosive atmospheres without having received appropriate training! The entire facility might otherwise be at risk!!

You can refer to ISA Technical Report 12.2. This concept is nicely described in it.

You can refer to ISA Technical Report 12.2. This concept is nicely described in it.

I went here - seems to be some good basic information.

Can you please repeat that?

Pardon?

OK agreed that cable should nt store enough energy to generate spark.

specification says :

Cable Capacitace + Transmitter Inbuilt Capacitance ≤ Barrier Inbuilt Capacitance

Cable Inductance + Transmitter Inbuilt Inductance ≤ Barrier Inbuilt Inductance

My ques is : "What will Happen if this condition is not fulfilled ?"

As above.

Either this:

or this:

Please make sure that all CR4 readers, including guests, are well out of the area before doing it.

I do not believe specification writes what you think it does.

1. The barrier has a maximum SAFE total capacitance/inductance for the external circuit on its "hazardous area" side. That is the sum of capacitance/inductance of cable, transmitters and anything else. The barrier's own capacitance/inductance "in-built" will usually be far less than its maximum safe values given on its approval certificate.
2. A greater capacitance could cause a spark which can ignite a flammable atmosphere.
3. A spark could then cause the events graphically pictured by other posts.
4. "What will Happen if this condition is not fulfilled ?" - When the dust has settled and the government investigation is complete, YOU will be the one listed as a contributer to cause of the fire/explosion.
   

Then Your system is not suitable use in Zone 0/1

Or Zone 2 either!

OKK....So when I have to use

Either Cable with lower values of Capacitance & Inductance OR

Barrier with higher Capacitance & Inductance

And when I m using Barrier with higher Capacitance & Inductance , how does barrier ensures that evrything remains safe?

The question is absurd.

Stop working on the project and get some proper training.

Sorry bit I dont agree that my doubt is baseless.

See I am gonna use trasmsitter with some inbuilt capacitance , inductance value.

I am gonna use cable with some defined values of capacitance , inductance value.

And certainly its going to store some energy in it !! Do you deny that ?

And as per ISA std. (TR 12.2) no std. permissible values of capacitance , inductance are given..

So the only way remained to check IS calc for my loop is by checking all these values wrt each other ..

Codswallop.

Stop working on the project and get some proper training before there is a fire, explosion, equipment damage, injury or fatalities.

Understood...Clearly...

I misunderstood the barrier concept..after reading ur post..i read some catalogs..now its pretty clear ..thanks

.....and the training?

wil surely take up sometime...

presently we hav already placed order for transmitters, cables n barriers so just cross checking these parameters loop wise.

Distances bw field instruments n control room are very short..like @ 200 mtrs at the max. so its not gonna add up much of capacitance & inductance...

Still checking all loops thoroughly to avoid any possible hazard!!!

.......and the training?

<sigh> This is an explosion just waiting to happen...

Try Measurement Technology Limited or SIRA (usual disclaimers).

It is important that appopriate training is completed before anything is ordered and installed, because it may be incorrect. The problem with on-line training is that it does not provide the pops, bangs and clouds of smoke that the one-to-one training that the above two providers have used so memorably to illustrate the hazards.

I hope you are not too "sore" at us for keeping on! I agree entirely with PWS advice on getting Measurement technology and SIRA literature. On training, if you are the designer, a safety audit would make lack of training a "top line non-compliance" and consequences would include the Director who refused to sign the training budget. If someone above you is trained, you have every right to get them check what you do and sign to approve it. So push for some training.