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Proses Control Terminology

Proses Control Terminology

Setelah sekian lama belum posting artikel2 baru, dikarenakan kesibukan TA dan kerja, maka untuk itu, saya kembali lagi untuk ingin berbagi wacana dan pengetahuan tentang Basic Engineering.

Dimana kali ini akan dibahas tentang proses Control Terminology. Proses control terminolgy ini meliputi Accessories, Actuator, Backlash, Capacity, Closed Loop Control Systems,  Open Loop Control Systems, Controller, Dead Time, Jenis Process Variable, Process Instrument, Measurement, Control, Manipulation.

yang pertama yaitu Accessories yang merupakan Alat yang terpasang pada actuator untuk melengkapi fungsi dan kerja dari actuator  sehingga menjadi unit kerja yang utuh. Contoh : positioner , regulator, solenoid, dan limit switch.

Kemudian Actuator merupakan Alat untuk membuka atau menutup control valve dimana sumber penggeraknya dapat      berupa  : Pneumatic, Hydraulic, atau secara Elektris

Backlash merupakan Nama umum yang diberikan untuk membentuk dead band yang dihasilkan dari discontinuity  sementara  antara input dan output dari sebuah device, contoh  bilamana input dari device mengalami perubahan arah. Slack atau mengalami  renggang atau terlepas dari  sambungan secara mekanis.

Capacity atau valve merupakan Rate dari suatu aliran (Flow) yang melalui Valve dimana telah ditentukan besarannya.

Closed Loop Control Systems, untuk yang ini mesti nya para mahasiswa teknik instrumentasi sudah tahu yaitu Sistem kontrol dimana informasi mengenai process variable secara kontinyu memberikan feed back (umpan balik)  ke controller untuk memberikan masukan, guna mengkoreksi process variable secara otomatis  (untuk gambar closed loop control system ini dapat anda dapat kan di google. hehehehe).

Open Loop Control Systems merupakan sistem kontrol dimana outputnya tidak mempunyai pengaruh terhadap komponen controller (untuk gambar closed loop control system ini dapat anda dapat kan di google. hehehehe).

Controller merupakan : Alat yang beroperasi secara otomatis dengan menggunakan algorithm  untuk mengontrol variabel kontrol. Dimana controler input menerima masukan dari status  process variabel dan selanjutnya akan memberikan output signal yang sesuai ke final control element

Dead Time merupakan Interval waktu, time delay  atau respon dari sebuah systems . contoh : Delay pada action controller, delay pada actuator operation.dll. Dimana input x(t) dan  output adalah y(t)      Y(t) = x(t – T)  dimana T adalah dead time

Jenis Process Variable yaitu terdapat bermacam2 diantara nya :

Pressure                                 Level                           Conductivity                  Flow

Temperature                            Mass                           Mass                            Specific Gravity

Density                                   Consistency                 Speed                           Force

Load                                       Torque

Process Instrument yaitu Alat yang digunakan baik secara langsung maupun tidak untuk  menampilkan satu atau lebih dari tiga fungsi dibawah yaitu :

Measurement : Pengukuran  dari sebuah variable

Control : Menghasilkan process variable yang dipertahankan pada  nilai yang telah ditentukan, dalam limit yang telah ditetapkan.

Manipulation : Memerintahkan Final Control Element agar secara langsung merubah Process Variable yang berfungsi untuk mengontrol dari Process Variable lainnya

 

Cukup sekian dulu artikel yang dapat saya tulis tentang Proses Control Terminology yang terdapat pada ilmu BASIC ENGINEERING. Masih banyak lagi artikel tentang BASIC ENGINEERING ini. Dan pasti saya usahakan untuk membaginya kepada saudara2 ku ini. Ditunggu aja artikel selanjutnya. Dan cukup sekian and

SALAM PERSAUDARAAN

 

 


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BASIC INSTRUMENTATION MEASURING DEVICES AND BASIC PID CONTROL Part 2

BASIC INSTRUMENTATION MEASURING DEVICES AND BASIC PID CONTROL Part 2

DP Transmitter Application
A DP transmitter is used to measure the gas pressure (in gauge scale) inside a vessel. In this case, the low-pressure side of the transmitter is vented to atmosphere and the high-pressure side is connected to the vessel through an isolating valve. The isolating valve facilitates the removal of the transmitter. The output of the DP transmitter is proportional to the gauge pressure of the gas, i.e., 4 mA when pressure is 20 kPa and 20 mA when pressure is 30 kPa.

2.1.6 Strain Gauges
The strain gauge is a device that can be affixed to the surface of an object to detect the force applied to the object. One form of the strain gauge is a metal wire of very small diameter that is attached to the surface of a device being monitored. For a metal, the electrical resistance will increase as the length of the metal increases or as the cross sectional diameter decreases. When force is applied as indicated in Figure 8, the overall length of the wire tends to increase while the cross-sectional area decreases. The amount of increase in resistance is proportional to the force that produced the change in length and area. The output of the strain gauge is a change in resistance that can be measured by the input circuit of an amplifier. Strain gauges can be bonded to the surface of a pressure capsule or to a force bar positioned by the measuring element. Shown in Figure 9 (next page) is a strain gauge that is bonded to a force beam inside the DP capsule. The change in the process pressure will cause a resistive change in the strain gauges, which is then used to produce a 4-20 mA signal.

2.1.7 Capacitance Capsule
Similar to the strain gauge, a capacitance cell measures changes in electrical characteristic. As the name implies the capacitance cell measures changes in capacitance. The capacitor is a device that stores electrical charge. It consists of metal plates separated by an electrical insulator. The metal plates are connected to an external electrical circuit through which electrical charge can be transferred from one metal plate to the other. The capacitance of a capacitor is a measure of its ability to store charge. The capacitance of the capacitance of a capacitor is directly proportional to the area of the metal plates and inversely proportional to the distance between them. It also depends on a characteristic of the insulating material between them. This characteristic, called permittivity is a measure of how well the insulating material increases the ability of the capacitor to store charge.

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BASIC INSTRUMENTATION MEASURING DEVICES AND BASIC PID CONTROL Part 1

BASIC INSTRUMENTATION MEASURING DEVICES AND BASIC PID CONTROL Part 1

Instrumentation is the art of measuring the value of some plant parameter, pressure, flow, level or temperature to name a few and supplying a signal that is proportional to the measured parameter. The output signals are standard signal and can then be processed by other equipment to provide indication, alarms or automatic control. There are a number of standard signals; however, those most common in a CANDU plant are the 4-20 mA electronic signal and the 20-100 kPa pneumatic signal. This section of the course is going to deal with the instrumentation equipment normal used to measure and provide signals. We will look at the measurement of five parameters: pressure, flow, level, temperature, and neutron flux.

2.1 PRESSURE MEASUREMENT
This module will examine the theory and operation of pressure detectors (bourdon tubes, diaphragms, bellows, forced balance and variable capacitance). It also covers the variables of an operating environment (pressure, temperature) and the possible modes of failure.

2.1.1 General Theory

Pressure is probably one of the most commonly measured variables in the power plant. It includes the measurement of steam pressure; feed water pressure, condenser pressure, lubricating oil pressure and many more. Pressure is actually the measurement of force acting on area of surface. We could represent this as: The units of measurement are either in pounds per square inch (PSI) in British units or Pascals (Pa) in metric. As one PSI is approximately 7000 Pa, we often use kPa and MPa as units of pressure.

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FLOW MEASUREMENT

Flow Sensor

Measurement of fluid flow rate is one of the most important in the process control flow. This measurement aims to find out how much capacity the flow of fluid to get the price is measured (measurement variables). The flow is generally measured by the amount of fluid velocity through a particular cross-sectional area, or
Qv = A x V. … … … … … … … … … … … … … … … … … … … … … … (2.1)
where: qv: the flow rate (m3 / s)
A: cross-sectional area of pipe (m2)
V: fluid velocity (m / s)
Four important factors in the measurement of fluid flow in pipes is:
• The speed of fluid
• Friction / fluid friction with the pipe
• The viscosity / viscosity of the fluid
• density / density of the fluid

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LEVEL MEASUREMENT

LEVEL MEASUREMENT

Level is one of the many variables encountered in industries such as temperature (temperature), pressure (pressure) and flow (flow). Therefore, the level of measurement is one of the important things in relation to the overall sustainability of the process. Failure level measurements may result in failure of a process or may even cause harmful factor for safety. Some examples of instruments relating to the measurement of the level shown in Figure 1.


Basic principles.
In general, the level of measurement is always based on the determination of boundary (interface) of two different fluid. For example between a fluid liquid with another liquid fluid, the fluid is a liquid with gas / vapor or gas between the gas fluid. By knowing where the limit is, then the level of fluid in question will be known.

Level measurement method.
There are several ways that can be used to measure the level of which is:
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