Instrumentation and Control Engineering

What Is LabVIEW? NI LabVIEW software is used for a wide variety of applications and industries, which can make it challenging to answer the question: “What is LabVIEW?” I have heard many conflicting opinions and debates over the years, so I thought it would be appropriate to take this opportunity to discuss what LabVIEW is.   LabVIEW is a highly productive development environment for creating custom applications that interact with real-world data or signals in fields such as science and engineering. The net result of using a tool such as LabVIEW is that higher quality projects can be completed in less time with fewer people involved. So productivity is the key benefit, but that is a broad and general statement. To understand what this really means, consider the reasons that have attracted engineers and scientists to the product since 1986. At the end of the day, engineers and scientists have a job to do – they have to get something done, they have to show the result...

Differences between RS 232 , RS422 , RS485 For understanding the difference between RS332 , RS422 and RS485 it is essential to understand   Single ended Transmission or Balanced   Differential Transmission or Unbalanced speed.For more advanced interfaces single return path for each signal in line twisted pair  cable is required Advantages of single ended transmission are Low system cost  Simple to Implement Noise and crosstalk Ground shifts Low data rates Low line length Low sensitivity to crosstalk Ground Noise rejection Common mode noise rejection High signalling rates Long length upto 1200m Twisted pair cable is required  Higher cost Point to Point - consist of one driver and one reciever Multi Drop - One driver with Multiple reciever Multi Point - Multiple drivers and Multiple Recievers Single Ended Point to Point Bus toplogy At Driver End Logic 0 - 5v to 15v Logic 1 - 5v to -15v Logic 0 +3 to ...

Proportional, Integral and Derivative Control Action Proportional (P) Action When measured value becomes higher than the set value (deviation), the upper end of proportional lever shifts to the right. Thus the flapper approaches to the nozzle and the back pressure of the nozzle, i.e., the pressure charged upon the pilot relay, increases. Consequently valve in pilot relay open and supply pressure flows into control side to increase the pressure. At the same time, this pressure is charged upon proportional bellows and lifts up proportional lever and thus flapper is detached from the nozzle and control pressure is set in proportion to such deflection. All of the above actions occur simultaneously in the actual operation. When both pointers overlaps (deviation is zero) control pressure becomes 60 kPa (20-100kPa). Proportional-Integral (PI) Action Assuming that the controller is acting properly and measured value and set value are in equilibrium, (or deviation is zero), and t...

Three-element Drum-level Control Three-element drum-level control is suited for handling variable feed water pressure or multiple boilers with multiple feed water pumps. In this design, three elements are used, each for controlling level, steam and feed water flow respectively. This system offers far better and advanced drum level control as compared to all other systems. For best control, correct flow values of both steam as well as feed water must be maintained with regard to density. A typical drum level control with three element module is shown in the figure below. Notes: https://drive.google.com/file/d/0B-ZhnHb2X39pTV9jOHg1ZnVvVW8/view?usp=sharing

                                                         ESD/ESV valves are one of the defense in protection layers against process hazards. These valves have a function which requires much more reliable performance than standard remotely operated on-off valves. IEC 61508 is a globally recognized new safety standard specific to process industry. Very strong guidelines are given there to process operators to test and prove the availability and functional safety of the safety loop including the final elements and ESD valves.Part 1 of the IEC 61508 demands certain documentation requirements for the development of safety critical devices. The selection of a specific type of safety valve is governed by several factors: -    Cost -    Valve construction -    Approvals -   ...

Flow Rate Equations are provided here for general use which are in accordance with: American Gas Association Report 3 American Gas Association Report 5 American Gas Association Report 8 American Petroleum Institute API MPMS 14.3.1 Following equations can be used for Mass Flow Rate, Volumetric Gross Flow Rate, Volumetric Net Flow Rate and Energy Flow Rate 1.   Mass Flow Rate at Flowing Conditions ‘Qm’ (Klbm/hr) Q  =( C  x  EV  x  Y  x   ∏/4  x  d2  x sqrt( 2  x  ΔP  x  Pf ) ) x 3600/ 1000 2.   Volumetric Gross Flow Rate at Flowing Conditions ‘Qv’ (MCF/hr) Q v  =  Q m   /   ρ f 3.   Volumetric Net Flow Rate at Base Conditions ‘Qb’ (MSCF/hr) Q b  =  Q m   /   ρ b 4.   Energy Flow Rate at Base Conditions ‘Qe’ (MMBTU/hr) Q e  =  (  Q b   x  HV  )  / 1000 No...

The simplest calibration procedure for a linear instrument is the so-called zero-and-span method. The method is as follows: 1. Apply the lower-range value stimulus to the instrument, wait for it to stabilize 2. Move the \zero" adjustment until the instrument registers accurately at this point 3. Apply the upper-range value stimulus to the instrument, wait for it to stabilize 4. Move the \span" adjustment until the instrument registers accurately at this point 5. Repeat steps 1 through 4 as necessary to achieve good accuracy at both ends of the range An improvement over this crude procedure is to check the instrument's response at several points between the lower- and upper-range values. A common example of this is the so-called -ve-point calibration where the instrument is checked at 0% (LRV), 25%, 50%, 75%, and 100% (URV) of range. A variation on this theme is to check at the -ve points of 10%, 25%, 50%, 75%, and 90%, while still making zero and span a...