PRACTICAL POSSIBILITIES Incorrect Calibration:

1.- Load the calibration error of the PH sensor.

2.- Load the calibration error of the Level sensor.

3.- Load the calibration error of the Flow sensor.

4.- Load the calibration error of the Temperature sensor.

Non Linearity:

5.- Non inverse linearity of the pH sensor.

6.- Non quadratic linearity of the Level sensor.

7.- Non quadratic linearity of the Flow sensor.

8.- No inverse linearity of the Temperature sensor.

Interchange of actuators:

9.- Interchange the bombs AB-1 and AB-2 between them during the operations of the controls ON/OFF and PID. (Affected sensor: Level sensor).

Reduction of an actuator response:

10.-In the PID, the real response of the proportional valve is half the amount calculated by the PID control. Thus, the maximum real opening that will be able to reach is 50%. (Affected sensor: Flow sensor).

Inversion of the performance in ON/OFF controls:

11.-In the ON/OFF control, the actuation sensor of the AVS-1 is inverted, acting, thus, on the same way as the others 2 valves (for a good control, it should operate the other way around to how the others 2 do it). (Affected sensor: pH).

Reduction or increase of the calculated total response:

12.-In the PID, the real action in the resistance is half of the total calculated. (Affected sensor: Temperature sensor).

The action of some controls is annulled:

13.-The Integral control does not work. It is reduced to a PD control (Proportional-Derivative).

14.-The Derivative Control does not work. It is reduced to a PI Control (Proportional-Integral).

15.-The Integral and Derivative controls do not work. They are reduced to a Proportional Control.

SPECIFICATIONS SUMMARY

The "FAULTS" mode consists on causing several faults in the unit normal operation. The student must find them and solve them.

There are several kinds of faults that can be grouped in the following sections:

Faults affecting the sensors measurement:

- An incorrect calibration is applied to them.

In this case, the student should proceed to calibrate the affected sensor through the values collection.

- Non-linearity.

When we have the measures taken by the sensor, a quadratic or inverse function is applied to them. Thus, the value measured will not be the real one, as in the case above mentioned, but when we calibrate again, the sensor will not operate linearly and we will not be able to calibrate it by lest squares fits.

Faults affecting the actuators:

- Actuators canals interchange at any time during the program execution.

This error does not admit any solution.

- Response reduction of an actuator.

By the reduction of the output voltage in analog outputs, we can get an response with a fraction of what it should be, either with a manual execution or with any control type (ON/OFF, PID...).

Faults in the controls execution:

- Inversion of the performance in ON/OFF controls. The state of some actuator is inverted, when it should be ON is OFF instead, and vice versa. The student should provide the correct operating logic.

- Reduction or increase of the calculated total response.

We multiply by a factor the total response calculated by the PID, causing, thus, the reduction or increase of the action really applied to the actuator, and the consequent instability of the control. The student should notify it and try to calculate this factor.

- The action of some controls is annulled.