99 PLC SCADA Interview Questions and Answers 2

99 PLC SCADA Interview Questions and Answers 2

List of PLC SCADA Interview Questions and Answers

21. Can split my one T/C signal to two separate instruments?

No. The T/C signal is a very low- level millivolt signal, and should only be connected to the device.
Splitting to two devices may result in bad readings or loss of signal. The is to use a “ dual” T/C probe, or convert one T/C output to a 4-20 mA signal by using a transmitter or signal conditioner, then the new signal can be sent can be sent more than one instrument.

22.What are the flow measuring instruments used in flow measurement?

ØDifferent pressure meters
ØPositive displacement
ØVelocity meters


23. Explain working of differential pressure measurement ?

Suitable restriction placed in flow stream causes a different pressure across it. As flow depends upon different pressure (Head) & area so any of them or both can be varied for varying flow.

24.What are the components of different flow sensor?

For creating different pressure: Orifice plate, Venturi Tube, flow Nozzle, pitot tube For measuring pressure: U- Tube Manometers, Ring- Balance
Manometer, P. Cell

25. What type of pressure sensors used in pressure measurement?

ØBourdon tubes
ØBellow elements
ØDiaphragm elements
ØDP transmitters

26. Explain working of different pressure transmitters.

 Process pressure is transmitted through isolating diaphragms and oil fill fluid to a sensing diaphragm. The sensing diaphragm is a stretched spring element that deflects in response to differential pressure across it.
The displacement of the sensing diaphragm, a maximum deflection f 0.004 inch (0.10mm), is proportional to the applied pressure, Capacitor plates on both sides of the sensing diaphragm detect the position of the diaphragm.
The transmitter electronics convert the different capacitance between the sensing diaphragm and the capacitor plates into a two- wire mA signal and a digital output signal.

27.      What is Control Valves?

The control valve, commonly named the final control element of control contains a pneumatic device that converts the control signal from the controller in action, regulation the flow.

28.      What type of control valves used in the industry?

ØON – OFF SERVICES:- Gate, Ball,
Diaphragm, Plug, Butterfly valves.
Butterfly, Diaphragm, Pinch valves.

29.      What are specifications of the control valve?

Following specifications are used for control valve
ØFlow medium and operating
ØFlow rate kg/hr or Nm3/hr                  Max/Min/Normal
ØInlet and Outlet pressure :
kg/cm2       Max/Min/Normal
ØMax. allowable diff. Pressure :
ØDensity of medium : kg/m3
ØCv: Valve Flow Coefficient

30.      What are the components of control valve?

  • ØActuator, Body, Trim, Diaphragm,
    Diaphragm plate, Actuator stem
  • ØActuator spring, Seat, Travel
    Indicator, Valve stem, Gaskets, Yoke, Hand wheel

31.      What is flow coefficient?

It is the flow of water (G=1, T=6 to 34 deg. C) through the valve at full lift in U.S. gallon per minute with a pressure drop across the valve of 1 psi.

Supervisory Control and Data Acquisition Software : Wonderware In Touch

32.      What is SCADA ? Role of MMI/HMI/SCADA in Industrial Automation

SCADA : Supervisory control and data acquisition
MMI : Man Machine Interface
HMI : Human machine Interface
This acts as an operator station. The operator can monitor as well as control the process parameters from this stations. Apart from online process data the operator will have access to historical and real-time trends, alarms and reports.
The operator can give commands to control hardware for opening the valve, change the set point, start the pump etc.

33.      What are Features of SCADA software?

 The common features of SCADA include Dynamic process mimic, Tends, alarm, Connectivity with hardware, Recipe management etc.

34.      Applications of SCADA.

 SCADA systems has many applications right industrial automation, power distribution to water management.

35.      Some of the leading SCADA companies

ØInvensys Wonder ware In Touch
ØSiemens WinCC (Earlier COROS)
ØAllen Bradley RS View (Earlier
Control View)
ØIntellution ifix (Earlier Fix
ØGE Fanuc Simplicity

36.      Types of Wonder ware SCADA packages

No. of I/Os- Wondeware In Touch comes is 64, 128,256,1000, and 64,000 tags package.
Development+ Runtime + Network (DRN)/ Runtime + Network (R+N) and View Node
D+R+N: With this packers development and editing of the application is possible, Runtime monitoring and control of the plant is possible and Networking is possible.
R+N: With this package development and editing of the application is NOT possible, Runtime monitoring and control of the plant is possible and Networking is possible.
Factory Focus: With this package developments and editing of the application is N OT possible, Runtime monitoring is possible but control of the plant is NOT possible and Networking is possible. This package is used a view node

37.      What type of licensing patterns used in the SCADA software

Typically two types of licenses are used in the SCADA software

ØDongle Key : It is a hardware
lock which can be put on the communication port of the PC.
ØSoftware Lock: Hare the software
code is the license. Typically can put the code while installation or transfer
the code from Floppy to hard- disk.

38.      Various EXE files used in Touch Software an there role

 InTouch : It is an application manager.
Using this you can create new application. Move between various application.
View: Window
viewer. This will start Runtime application. From this you can monitor and
control the plant.
WM: WM.XE is
Window maker. This will start the development package in InTouch. Using you can
you can develop the application.

39.      Types of Window?

Replace: Automatically
closes any window (s) it intersect when it appears on the screen including
popup other replace type windows.
Overlay: Appears on
top of currently displayed window (s) and can be larger than the window (s) it is overlaying. When an overlay window is closed, any window (s) that ware hidden behind it will reappear.
Clicking on any on any visible portion of a window behind an overlay window will bring that window to the foreground as the active window.
Popup: Similar to
an overlay window except, it always stays on top of all other open windows (even if another window is clicked) Popup window usually require a response from the user in order to be removed.

40.      What is Symbol Factory?

Symbol Factory contains symbols which cab be readily used in the application. The symbol is contains include various Tanks, Reactor, Pipes Icons, and Flags.

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