Industrial Electronic Department Copyright of German Malaysian Institute. All rights reserved

Industrial Electronic Department Copyright of German Malaysian Institute. All rights reserved TRANSMISSION SYSTEM Level Range = 0 – 10 ltr inlet outlet Transmitter d/p Cell Controller Control Valve When the sensor measures the controlled variable, the measured value must be transmitted in some manner to the controller. In a similar fashion, it is necessary to get information from the controller to the final control element.

Industrial Electronic Department Copyright of German Malaysian Institute. All rights reserved Two common type of transmission system in use Pneumatic Transmission Electrical Transmission TRANSMISSION SYSTEM

Industrial Electronic Department Copyright of German Malaysian Institute. All rights reserved PNEUMATIC TRANSMISSION A pneumatic transmitter is a device that senses some process variable and translates the measured value into an air pressure that is transmitted to various receiver devices for indication, recording, alarm and control.A pneumatic transmitter is a device that senses some process variable and translates the measured value into an air pressure that is transmitted to various receiver devices for indication, recording, alarm and control. The most common pneumatic transmission signal is 3-15 psig. (The most common pneumatic transmission signal is 3-15 psig. (0.2 – 1 Bar, 0.2 – 1 kg/cm2) May be used for distances up to several hundred feet.May be used for distances up to several hundred feet. Pneumatic signal can be utilized in the hazardous or highly flammable area. This is because pneumatic didn’t create sparks that could ignite fire or explosion.Pneumatic signal can be utilized in the hazardous or highly flammable area. This is because pneumatic didn’t create sparks that could ignite fire or explosion.

Industrial Electronic Department Copyright of German Malaysian Institute. All rights reserved ELECTRICAL TRANSMISSION Most common transmission system.Most common transmission system. The most common electrical transmission signal isThe most common electrical transmission signal is 4-20mA. ( 4-20mA. (0 - 20mA, Volt, Volt) 4mA represents zero, and 20mA represents 100% or full scale.4mA represents zero, and 20mA represents 100% or full scale. A twisted pair of copper wires is used to form a dc current loop.A twisted pair of copper wires is used to form a dc current loop. Current is preferred over voltage because it is more immune to noise and it requires only two wires.Current is preferred over voltage because it is more immune to noise and it requires only two wires.

Industrial Electronic Department Copyright of German Malaysian Institute. All rights reserved Process Engineering Unit (Signal) The engineering signal can be recognized according to the PROCESS BEING CONTROL (x OR PV) for instance FlowLevelPressure Temperature Liter/min Gal/min Ft 3 /min etc Bar kPa Pa Psi Kg/cm2 inH2O mmH2O etc O C O K O F Liter Feet Meter Mm Gal m 3 Ft 3 etc

Industrial Electronic Department Copyright of German Malaysian Institute. All rights reserved 1. What is the flowrate of the flow process if the measuring instrument indicate 6 mA ? Flow Range is 0 – 50 ltr/Hr, Instrument range is 4-20 mA 2. A final control element is only received a pneumatic signal to operate, but the signal output from controller is in VOLT. Calculate what is the Conversion signal received by the final control element if output of the controller is 4.6Volts?Controller signal range is 1- 5Volt and FCE is 0.2 – 1 kg/cm2 3. Output from Measuring Instrument is 4 – 20 mA, unfortunately the controller is only received 1- 5 Volts signal. Calculate and determine how to convert the signal so it can be suit to controller application. ASSIGNMENT