Page 188 - Practical Power System and Protective Relays Commissioning

190 Practical Power System and Protective Relays Commissioning

5. Frequency relays;
6. Temperature relays;
7. Flow relays;
8. Vibration relays.

18.2.3 CLASSIFICATION BASED ON PRINCIPALS OR
STRUCTURES

1. Differential relays;
2. Impedance relays;
3. Electromechanical;
4. Solid state-static relays;
5. Digital-static relays;
6. Numerical-static relays;
7. Thermal relays.

18.2.4 CLASSIFICATION BASED ON CHARACTERISTICS

1. Distance relays;
2. Directional relays;
3. Inverse time relays;
4. Definite time (DT) relays;
5. Under voltage relays;
6. Earth fault or phase fault relays;
7. High- or low-speed relays;
8. Directional comparison relays;
9. Segregated phase relays;
10. High-impedance or low-impedance differential relays;

Subchapter 18.3

Design of Protective Relaying Systems

The design of a protection power system is divided into several zones; each
zone needs a group of relays. The design of a protective relaying system
depends on the following factors:
1. Economics, the importance of the protected power system components
and the required degree of protection against the cost.
2. Availability of the measured input signals, current transformers (CT), and
voltage transformer (VT) locations.
3. Design philosophy used before, and previous experience.