Answer Posted / wilson

Most people has got the answer correct for "why 4-20mA and
not 0-20mA". Yes, it is to prevent undetected failure of
circuit or instrument.

As for "why not 3 to 15 or anything". I assumed the
question is not "why not 3-15mA" because not one use 3-
15 "mA", if really you have to ask that, you might as well
ask why not 2.314 to 33.776 mA.

3 to 15 is used, but in pneumatic system and the unit is in
PSI. i.e. 0.2 to 1.0 bar. The reason for 3PSI (or 0.2bar)
is the same as 4mA, to prevent undetected failure.

which type of zones used for boiler? & why ?

1857

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-/5A. What is the meaning and limitations of this in energy meter constant. It is a 3 phase LT Energy Meter. If this Energy Meter is connected through a CT of ratio 200/5 Amps, then what is the multiplying constant and how its will be calculated.

2443

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how u calibrate sox nox co2 co in cemps?what is opacity n HPm?tell the standard parameters of cems?

3654

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draw shematic diagram of c/v positioner(smart type)?

2211

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can u plz send me technical questions asked in SCHNEIDER ELECTRICAL technical paper?

4725

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can you send remote seal interface level transmitter calculation steps for oil water saperator.

2610

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why we r opening HOT BYPASS valve during startup of a compressor?

2093

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in mass flow meter what is drive friquancy ?

2087

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How to Calibrate Coriolis Flow transmitter in field

1259

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How ejector(or)evactor air pump is working in thermal power plant?

6592

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what is diffrance between FF & SMART, explain with difination

3203

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How many interlocks at turbine side?

1922

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what is the procedure to callibrate temp controller ,pressure controller,etc. suppose a temp controller showing error 1.5 degree centigrate how can i minimize it.

2342

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plz you help about Que paper of mahagenco previous your,any model paper relad to it{maharastra power genration}

2325

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give eg of how I/P is used in control loops

1935

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