【Daily Question 20090305】What does instrument calibration include?

The zero point and range of the transmitter must correspond one-to-one with the process design parameters; for differential pressure transmitters used in throttling devices, it is important to determine whether squaring should be performed on-site or within the configuration settings； Also pay attention to the zero offset. Gauge calibration. Terminal cabinet channel verification. The rating of the flow meter is generally quite high, and the on-site conditions do not permit any adjustments to be made. The debugging of a control system focuses on whether the forward and reverse actions of the control loop meet the process requirements. Check whether the orientation of the various buttons on the simulated hand controller is convenient to use (usually by verifying whether there are any changes in the online configuration). Ensure that the logic of the interlock circuits meets the requirements of the process design (this is mandatory), and that the sequence of actions taken is correct once the conditions are met.

Table single instrument debugging: 1. Verification of the power supply and signal circuits for individual instruments. 2. The instrument calibration (including visual inspection) meets the requirements. Commissioning of the control system: verification of cabinet power supply, validation of I/O channels, and confirmation of alarm and interlock functions. Special attention should be paid to the fact that system commissioning requires the involvement of industrial personnel, designers, and construction workers; of course, instrument maintenance is also necessary. It’s definitely not comprehensive; everyone please add to it.

Table single instrument debugging: 1. Verification of the power supply and signal circuits for individual instruments. 2. The instrument calibration (including visual inspection) meets the requirements. Commissioning of the control system: verification of cabinet power supply, validation of I/O channels, and confirmation of alarm and interlock functions. Special attention should be paid to the fact that system commissioning requires the involvement of industrial personnel, designers, and construction workers; of course, instrument maintenance is also necessary. It’s definitely not comprehensive; everyone please add to it.

The zero point and range of the transmitter must correspond one-to-one with the process design parameters; for differential pressure transmitters used in throttling devices, it is important to determine whether squaring should be performed on-site or within the configuration settings； Also pay attention to the zero offset. Gauge calibration. Terminal cabinet channel verification. The rating of the flow meter is generally quite high, and the on-site conditions do not permit any adjustments to be made. The debugging of a control system focuses on whether the forward and reverse actions of the control loop meet the process requirements. Check whether the orientation of the various buttons on the simulated hand controller is convenient to use (usually by checking whether there are any changes in the online configuration)

Is the fourth floor the mask for the third floor? Single-unit debugging includes range, zero point, and midpoint testing, as well as testing of the instrument’s transmitted output signal. Integrated debugging involves testing of channel connectivity, voltage, output control, and the overall circuit integration

Monomer calibration: (1) The instrument to be calibrated shall have an intact appearance and seal, complete accessories, no missing or damaged parts inside, a clear and complete nameplate, and its model, specifications, and material shall comply with the design requirements. (2) Before calibration, the instrument to be calibrated shall undergo performance tests in accordance with the following provisions ； 1. Before powering on electric meters, it is necessary to check first whether the operation of their electrical switches is flexible and reliable. The insulation resistance value of the electrical wiring. It shall comply with the **instrumentation industry standards or the instructions for the installation and use of instruments. II. The damping characteristics of the instrument in question and the speed at which its pointer moves shall comply with the **professional standards for instruments or the instructions for their installation and use. The indication and recording functions of the instrument should: 1. The instrument’s panel and dial must be clean and clear ； 2. The pointer moves smoothly, without friction, jumping, or sticking ； 3. The marking lines or printed dots on the recording device are clear, with no breaks, missing marks, or irregular markings ； 4. The numbers (or colors) of the print dots on the recording paper must correspond to the numbers of the input signals indicated on the switch and terminal boards. III. The alarm device shall undergo a test of its alarm function performance. IV. Electric actuators, pneumatic actuators, and pneumatic diaphragm control valves shall undergo a full-stroke time test. V. The control valve shall undergo a valve body strength test in accordance with the provisions of Article 2.1.6 of these specifications. VI. Square roots calculators and square root integrators equipped with small-signal rejection devices shall undergo small-signal rejection performance tests. VII. The regulator shall undergo a bidirectional switching test for manual and automatic operation; electric regulators with a soft manual function shall also undergo the following tests ； 1. Test of the time required for the output indicator to travel through its full stroke in both fast and slow positions when in soft manual mode ； 2. Test of output hold characteristic when the soft manual output is 4.960 volts (19.8 milliamps) ； 3. Test for two-way switching between soft and hard manual operation. (3) The instruments or regulators under calibration shall have their accuracy adjusted for the following parameters: First, the instruments under calibration must have their deadband (i.e., sensitivity limit), basic errors in the forward and reverse operating ranges, as well as hysteresis adjusted. II. The regulated regulator shall meet the following requirements: 1. Manual operation error test ； 2. Tuning of the closed-loop tracking error of the electric regulator ； Adjustment of control point deviation for pneumatic regulators ； 3. Proportional band, integral time, differential time scale error test ； 4. When there are additional mechanisms, the motion error of those mechanisms should be adjusted. System commissioning: (1) System commissioning shall be carried out prior to the process trial run, and only after the following conditions are met: First, the instrumentation system must be installed, the pipelines must have been cleaned and pressure-tested successfully, the insulation of the cables must be satisfactory, and the value of the additional resistance must meet the required specifications ； II. The power supply, gas supply, and hydraulic supply meet the requirements for the operation of the instruments. (2) Calibration of the detection system: It shall comply with the following requirements: First, an analog signal shall be input at the signal generation end of the system (i.e., at the transmitter or sensing element), and the system’s error shall be checked; this error value shall not exceed the square root of the sum of the squared allowable basic errors of all the instruments in the system ； II. When the system’s error exceeds the specified limits, each instrument within the system should be adjusted individually, and the circuits or pipelines should be inspected. (3) The commissioning of the control system shall comply with the following provisions: 1. In accordance with the design specifications, check and determine the operating direction of the regulators and actuators ； II. At the signal generation end of the system, an analog signal is applied to the regulator to examine its basic error, the output holding characteristics during soft manual operation, as well as the proportional, integral, and derivative actions, along with the two-way switching performance between automatic and manual modes ； III. Use the output signal of the manual operating mechanism to check the full stroke movement of the actuator from the starting point to the ending point. If there is a valve positioner, it should be inspected together with the valve positioner. (4) The commissioning of the alarm system shall meet the following requirements: First, the alarm setpoints within the system, as well as the alarm mechanisms in instruments and electrical equipment, shall be adjusted according to the setvalues specified in the design ； II. Input an analog signal at the system’s signal generation terminal, and check whether the audio and lighting signals meet the design specifications. (5) The commissioning of the interlock system shall meet the following requirements: 1. The setting and testing of the alarm setpoints within the system, as well as those of the alarm mechanisms in instruments and electrical equipment, shall comply with the requirements of Article 4 ； II. In addition to conducting individual tests, the interlocking system shall also undergo full-scale integrated tests.

1. Verification of terminal cabinet channels. 2. Verification of the range and installation of on-site and remote sensors. 3. Individual testing of electrical equipment. 4. Sequential debugging of the process. 5. Debugging of the lower-level and upper-level systems.

Pre-debugging of conventional instruments, secondary debugging of instruments, power supply and operation of the control system, simulation tests of the control system, as well as inspection, configuration, and setting of the card components in the instrument control system within the DCS system; debugging of application software, and implementation of interlock controls in coordination with electrical and other related disciplines.

What was said on the 8th floor covers it pretty well; debugging also depends on the stage at which it is carried out, as the tasks involved in debugging vary at different stages.

I’m not working in the field of instruments; I just observe the instrument engineers at our factory while they carry out adjustments: testing the power supply, testing the circuit signals, testing the central processor, checking the circuits, and testing the field instruments as well.

Feng Ren is not a specialist in instrumentation; he works in chemical process design. Based on his work experience, single-unit commissioning involves zeroing and calibrating electrical and instrumentation components to ensure the proper functioning of the power supply system. Overall debugging is equivalent to coordinated debugging; it mainly involves tuning the logical programs and control principles to meet the requirements of the production process.

Table single instrument debugging: 1. Verification of the power supply and signal circuits for individual instruments. 2. The instrument calibration (including visual inspection) meets the requirements. Commissioning of the control system: Verification of cabinet power supply, validation of I/O channels, confirmation of alarm and interlock functions, instrument commissioning.

Table Single Instrument Debugging: 1. Confirmation of the circuit for a single instrument. 2. Adjust the zero point and full scale of individual instruments; if possible, select a few points in between as well. Debugging of the control system: 1. Whether the control system is operating properly ； 2. Are the alarm and interlock functions working properly? ； 3. Is the emergency handling function working properly? ；

Instrument calibration involves adjusting and testing the individual instruments as well as the control systems used in industrial automation, with the aim of verifying that their technical performance meets the specified standards or design requirements, and that their parameters conform to those outlined in the design drawings. The commissioning of individual instruments mainly involves three aspects: power-on inspection, such as flow meters ； Performance tests, such as the thermoelectric properties of thermocouples, the accuracy class of instruments, insulation tests, and strength tests, etc ； Range setting, such as the zero point range of the gauge and the initial positioning of the pressure gauge ； Parameter adjustment, such as the output of current from instruments and the setting of switch thresholds. The debugging of control systems mainly includes the following aspects: system testing, which primarily involves checking and testing systems such as PLCs and DCS ； Accuracy check: An accuracy check is performed on the indicating and control loops; the control loop is divided into input and output components ； Functional tests mainly include the regulation function of control circuits (open-loop tests) and tests of the logic system functions; the logic functions are further divided into causal logic and sequential control logic, with the former being influenced by a single condition while the latter is affected by both time and conditions.