The document is a lecture presented by Dr. Ahmad Al-Subhi on electrical switchgear, covering its definition, types, and major equipment involved in power systems. Switchgear is essential for switching, controlling, and protecting electrical circuits, including devices such as circuit breakers and fuses. The lecture also distinguishes between indoor and outdoor switchgear based on voltage and presents various protective devices integrated with switchgear for improved functionality.

1. Dr. Ahmad Al-Subhi
SWITCHGEAR AND PROTECTION
Lecture 1
INTRODUCTION TO ELECTRICAL
SWITCHGEAR
Prepared by: Dr. Ahmad Al-Subhi

2. Outline:
• What is switchgear?
• Switchgear types.
• Major switchgear equipment.
Prepared by: Dr. Ahmad Al-Subhi

3. What is Switchgear?
- Switchgear involves the apparatus used for switching,
controlling and protecting the electrical circuits and
equipment in the power system.
- The term “switchgear” is a generic term encompassing a
wide range of products like circuit breakers, switches, off-
load isolators, fuses, contactors, etc…
Prepared by: Dr. Ahmad Al-Subhi

4. - A general term covering switching and interrupting devices
and their combination with associated control, metering,
protective, and regulating devices; also assemblies of these
devices with associated interconnections, accessories,
enclosures, and supporting structures, used primarily in
connection with the generation, transmission, distribution
and conversion of electric power.
C37.100-1992 - IEEE Standard Definitions for Power Switchgear:
What is Switchgear?
Prepared by: Dr. Ahmad Al-Subhi

5. Prepared by: Dr. Ahmad Al-Subhi

6. - In its initial design, it was a mechanical switch that physically
separated or joined two or more conductors.
- Development over time has made switchgears offer control,
protection and isolation including various electrical equipment
and circuits.
- Switchgears comprise more than one device to form a system
that collectively work together.
- Power switchgear is used throughout the entire power system,
from generation to industrial plants to connect incoming power
supply and distribute power to consumers.
Prepared by: Dr. Ahmad Al-Subhi

7. Switchgear Types:
- Indoor: for voltages below 26 kV
- Outdoor: for voltages beyond 26 kV (large area is needed)
Prepared by: Dr. Ahmad Al-Subhi

8. Major Switchgear equipment:
• Fuses.
• Circuit breaker.
• Recloser.
• Sectionalizer.
• Isolator.
• Surge arresters.
• Wave trap.
• Current transformer.
• Voltage transformer.
• Relays.
• ATS and UPS.
Overcurrent protective devices
Integrated with recloser to improve its functionaility
Off load switch
Provides protection from lightning
Initiate the relay working
The brain of power system protection
Prepared by: Dr. Ahmad Al-Subhi
Low pass filter to block high frequency signals
Used for emergency conditions

9. Prepared by: Dr. Ahmad Al-Subhi