Top Instrumentation Interview Questions :: Top Instrumentation Interview Questions en-us WHAT IS THE DIFFERENCE BETWEEN PLC AND DCS programming logic control & digital logic control what is the diffrence between mmwc and kg/cm2 for pressure measurmen when we r measuring very low pressure :: mmWC and measuring high pr. :: kg/cm2/bar/psi... ok for example we r measuring like boiler furnaces pressure(draft) i.e very low pr.(250mmWC) so we r measuring in mmWC, and when we r ca What is the basic principle of vibration measurement by BENTLY NEVAD This is a very good, accurate writeup done by someone else for a similar question earlier on. Hope it helps. The vibration sensors used in turbine, generator etc are all same type i.e proximity type of sensors. The sensor are mounted at the p what is plc? Basic function of plc? application of plc in industry? W Plc is a simple computer which used for automation of real world processes such as controlling of machinery in a industry. Plc is a microprocessor based device with input and output circuitry that monitors the status of the field connected " why 4-20 mA signal is preferred over a 0-10V signal generally in a transister some amount of voltage is required for turning it on. this voltage is the cutin voltage. up to this voltage the exists a nonlinerity in its charecteristics. beyond this cutin voltage the char. of transister is linear what is full form of SMART Self-Monitoring, Analysis, and Reporting Technology HOW TO CHECK THERMOCOUPLE AND RTD & WHAT IS THE DIFFERENCE BETWE Thermocouple when senses gives "mv" readings to the transmitter. RTD gives "ohm" readings to the transmitter. For checking put the multimeter in resistance mode and if the the sensor is throcouple the meter will indicate al what is DCS? dcs is a distributed control systems what is mean by loop checking? I think loop checking is another way of calling "feedback" ... m not sure abt it.. wht is Zero Elevation and Zero Suppression? ZERO ELEVATION MEANS WHITE FIXING THE TRANSMITTER LOWER THAN THE PROCESS LINE IT GOES NEGATIVE .TO CHANGE FROM NEGATIVE WE ADJUST THE ZERO SCREW. ZERO SUPPRESSION IS WHILE FIXING THE TRANSMITTER ABOVE THE PROCESS LINE IT What is the meaning of Dry contact and Wet Contact related to to sen dry contact is that the contacts are floating. One example is the COM, NC and NO contacts of the relays. If no voltage is connected to them, it is called dry contacts. Volt-free and dry contact mean the same thing. If a control system supplier what is the basic working principle of I/P and Positioner in any con I/P is basiclly working on the flapper and nozzle principle.And the positioner is working on the Forced balance principle. what is diff between sensors and transducers.explain with ex? sensor: which converts one physicalquantity into electrical quantity. Transducer which converts one form of energy into another form.Example pressure Measurement{BOURDAN TUDE}. WHICH INSTRUMENT USED TO CALIBRATE CONTROL VALVE? we can calibrate the control valve by using source meter which is used to give 4 to 20 ma source to I/P , if any error in the I/P ,we can adjust the zero or span of I/P.if any error in the valve position ,adjust the zero or span in the posisner o what are the different types of Protocols? & their applications. TCP- COMMUNICATION PROTOCOL IP-iNTERNET PROTOCOL HART PROTOCOL FIELD BUS PROFIBUS