Strip chart recorders are widely used to record variation of a variable quantity or quantities with respect to time axis. In some applications in industry, it is required to know the variations in a particular parameter which changes with respect to time and is needed to be recorded for record purpose.
Strip chart recorder, as the name implies, consists the strip of chart on which the variations of the variable are plotted.
The following components are required: –
- PEN (Stylus): –Used for marking the variations of variable quantity on the strip chart.
- Chart paper: – This chart paper is in the form of strip. This paper is rolled and moves under the pen as the time goes on.
- Chart paper drive mechanism: – To move the chart paper under the pen a driving mechanism is required. In this mechanism, the speed of the moving chart can be controlled.
- Event marker: – This marker is used to mark the time for which the variations of quantity are required to record.
- Signal conditioning system: –This system consists of discrete circuits, filters, amplifiers, ADC, DAC etc.
Operation:-
- Firstly, to record any quantity we require a chart. The chart is loaded in the recorder.
- Next, the speed of the moving chart is needed to be selected. This moving speed is adjusted by chart drive system. It has a stepper motor which rotates in steps for the chart to move at a constant step angles.
- Now, the event marker notes down the event on the chart. This is done by giving the event input signal to the event marker.
- After this the input signal is applied to recorder by selecting a proper range which can be easily measured. To properly mark the variable quantity of the input signal, the signal is needed to be conditioned which is done with the help of signal conditioner.
- The output of the signal conditioner is given to the servo motor which is connected to the pen and ink stylus.
- The servo motor moves as it gets the input signal.
- The pen starts moving on the chart and the instantaneous value of variable quantity is recorded.
So, this is how the strip chart recorder works. It is a better instrument which helps to store the variable quantity at every instant of time.
References:-
- Electronic instrumentation by Kalsi