02-calibration concept (13 hlm)

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FUNDAMENTALS OF

INSTRUMENTATION AND CONTROL

PHILOSOPHY

CALIBRATION CONCEPT

PENDAHULUAN

• Setiap instrumen memiliki paling sedikit satu

masukan (input) dan satu keluaran (output).

InputTekanan

Sinyal

Sinyal

OutputSinyal

Pembacaan

Daya

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PENDAHULUANKalibrasi adalah menera instrumen dengan memakai instrumen

standar. Tujuannya adalah menepatkan hubungan antara input dan

ouput instrumen.

PENDAHULUAN

CALIBRATION DAN RE-RANGING

CALIBRATION adalah mengecek dan mengatur untuk

menepatkan kerja instrumen dalam rentang tertentu (biasanya

dari minimum hingga maksimum)

RE-RANGING adalah menyetel nilai minimum dan maksimum

sehingga diperoleh nilai sensitivitas tertentu

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Hubungan Input-Output

Hubungan Input-Output

Pressure Transmitter

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ZERO ADJUSTMENT

Pressure Transmitter

Span Shift

Pressure Transmitter

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Effect of Linerarity

Pressure Transmitter

Effect of Hysteresis

Pressure Transmitter

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Typical Calibration Errors• If the technician “blocks and equalizes” a DP instrument and it

properly reads zero, its calibration is probably good across the entire range.

• If the DP instrument fails to read zero during this test, it definitely needs to be recalibrated.

Documentation

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LRV and URV Setting

LRV and URV Setting

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ADC Error

LRV and URV Setting

DAC Error

PRACTICAL CALIBRATION STANDARD

1) Electrical Standard

– Weston cell, 1.0183 V, low uncertainty

and low drift. Sensitive to vibration.

– High accuracy digital voltmeter

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PRACTICAL CALIBRATION STANDARD2) Temperature Standard

– For RTD and thermocouple

PRACTICAL CALIBRATION STANDARD3) Pressure Standard

– Deadweight Tester

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PRACTICAL CALIBRATION STANDARD3) Pressure Standard

– Deadweight Tester

PRACTICAL CALIBRATION STANDARD3) Pressure Standard

– Deadweight Tester

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PRACTICAL CALIBRATION STANDARD3) Analytical Standard

– A typical self-calibration system

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INDIVIDUAL CALIBRATION

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Disadvantages of Individual Calibration Advantages of Individual Calibration

a. The entire loop is not verified within

tolerance

b. Possible mistakes on re-connect or

install

c. Less efficient use of time to do one

calibration for each loop instrument

as opposed to one calibration for

the loop.

a. Correct instrument will be

adjusted

b. More compatible with

multifunction calibrators

LOOP CALIBRATION

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Loop Calibration Disadvantages Loop Calibration Advantages

a. Wrong instrument may be adjusted to

bring the loop within calibration.

b. Not as compatible with multifunction

calibrators used for “paperless” data

collection

a. Entire loop, including sensor, is

verified within tolerance

b. Mistakes on-reconnect or install can

be minimized

c. More efficient use of time to do one

calibration for loop as opposed to one

calibration for each loop instrument.

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