Answer Posted / abdus sattar mollah
initially,0-20ma of current is used as an transmitting
standard unless a objection was met.It was that:0 ma of
current used to indicate no signal/minimum signal from a
signal conditioner but if there is a faulty condition(such
as loop break),then also it will be show 0 ma of
current.Operator may think that there is no signal but
actually a fault has occured.So he cant distinguish between
them unless the plant is damaged.This is called TRUE ZERO.
So,after a reserach a new standard was proposed i.e 4-20 ma
of current.There was minimum interference in this
range,good quality transmittance,low power consumptions.So
this satndard is used.
Is This Answer Correct ? | 37 Yes | 1 No |
Post New Answer View All Answers
flow transmeter accuracy 0.075% of full scale & find ucertainty is 0.025 % so what is maximum limit band of uncertainty
Meaning of the following a. IOP- Manimum; b. IOP- Maximu,;
What is Alpha & Beta fctors related to Orifice Plate & its relation with flow?
what is maxdna ?. explain about the software details.
Basically iam Instruemntation Engineer, but Iam interested in Instruments design engineering, so plz guide, is there any course, training or Softwres to become Instrument design engineer??.
you are on site,the plant trips,you are approached by operations,what do you do?
selection of the zener barrier for the hazardeous area zone 0
what is isloted barrier how it works and what are the main purpose.how it make safe area.
How will you calibrate an Absolute Pr.Transmitter of range 400mmHg absolute ?
what is the procedure of O2 sensor(ABB) calibration?
how do calibrate the valves.. with clear manual
how to work MIL contol valve posistioner ?
Explain plc level and its type?
In turbine, what does term CDP, NI, NH, HSSOC, means
what is installation and commissioning of (fat & sat) of power plant dcs ? this question keeps in desirable conditions of one company .