Power System Protection

Gee, these seem to me to be pretty self explanatory. Unless you are having trouble understanding what a pickup means in a control system. A pickup is not in this case a way for an engineer to have a good time. A pickup is a sensor, a transducer. It converts some physical property into an electrical signal that other parts of the system can use. A microphone is a pickup device. No pickup device works flawlessly. The difference between the pickup signal produced and the actual signal it should have produced is the error.

You have advantage of the Internet and yet you still want somebody else to do the donkeywork.

pick up error is the tolerance error % allowed for pick up voltage of a coil in relays, contactors etc.. Extremely inverse characteristic is one the curve which is used for inverse definite minimum time overcurrent & earth fault protection.