What is Protection, control and automation

Protection

Each part and each equipment in the electrical plant and power system are protected against abnormal conditions by Protection Systems. During normal condition the protection system is alert and watchful. When abnormal condition develops in the protected zone, faulty part from the rest of the healthy system. The protective actions are taken instantaneously (within a few cycles without deliberate time lag) or with certain time lag of the order of few seconds. e.g. Fuse provide protection to house wiring against short circuit currents or over load currents. Miniature Circuit Breakers also provide protection to house wiring against short circuit currents or over load currents. During a fault within a transformer winding, the Differential Protection acts and trips the circuit breakers on both the sides of the transformer within 10 cycles of 50 Hz wave.

Control

The control system ensures that the electrical plant operates within assigned performance limits of various variables and gives desired optimum performance. The output is compared with desired output and corrective actions are taken to adjust the appropriate input variables to ensure satisfactory output.

Controllers may be Manual or Semi Automatic or Completely Automatic (without human intervention).

e.g. Voltage Control of Substation bus by means of On Load Tap Changing Transformer.

Monitoring

Monitoring means checking the performance at regular intervals. If the variables are showing unhealthy trend, appropriate corrective action should be taken to prevent failure. Significant variables are measured periodically, scanned at regular interval and indications of abnormal trends are flashed on control panel facia and alarm is sounded.

Automation

The engineering science and art or technique of making a process more automatic, self moving, self controlled and without human intervention. Automation involves investigation, Design, Development and Application of methods to render the process or plant or equipment automatic, self controlled, self moving, self acting, etc.

e.g. Automatic speed control of Turbine Generator shaft by means of Governor Action.