Posts Tagged ‘Substation’

What is Substation Automation?

Substation Automation may be best described by referring to Figure 3.1.


Figure: Functional Structure of Substation Automation

Substation Automation, by definition, consists of the following main components:

  • Electrical Protection
  • Control
  • Measurement
  • Monitoring
  • Data Communications

Substation Automation can be defined as a system for managing, controlling and protecting a power system. This is accomplished by obtaining real-time information from the system, having powerful local and remote control applications and advanced electrical protection. The core ingredients of a Substation Automation system are local intelligence, data communications and supervisory control and monitoring.

The term Substation Automation is actually too restrictive and may be misleading. It is too restrictive in the sense that it refers specifically to a substation only. However, the concepts encompassed in the definition have a much wider application than being limited only to substations. It is applicable to electrical power networks at large, from High Voltage transmission networks, to Medium Voltage distribution networks, to Low Voltage reticulation networks. The term may be misleading in that automation usually refers to some type of process automation, whereas the concepts involved in Substation Automation are quite unique and far removed from process automation, although there is some common ground in the underlying principles.

The term Substation Automation evolved due to the fact that most of the equipment that forms the core of such a system, is located in an electrical substation or switch-room, and these modern, intelligent devices ensure that the need for human presence or intervention in a substation is limited. The components of a Substation Automation system aim to protect monitor and control a typical electrical substation.

(Note: The term “substation” will be used throughout the text to describe mainly a building housing electrical switchgear, but it may also include switchgear housed in some sort of enclosure, for example a stand-alone Ring Main Unit, etc.)

Electrical Protection

Electrical Protection is still one of the most important components of any electrical switchgear panel, in order to protect the equipment and personnel, and to limit damage in case of an electrical fault.

Electrical protection is a local function, and should be able to function independently of the Substation Automation system if necessary, although it is an integral part of Substation Automation under normal conditions. The functions of electrical protection should never be compromised or restricted in any Substation Automation system.


Control includes local and remote control. Local control consists of actions the control device can logically take by itself, for example bay interlocking, switching sequences and synchronizing check. Human intervention is limited and the risk of human error is greatly reduced.

Local control should also continue to function even without the support of the rest of the Substation Automation system. Commands can be given directly to the remote controlled devices, for example open or close a circuit breaker. Relay settings can be changed via the system, and requests for certain information can be initiated form the SCADA station(s). This eliminates the need for personnel to go to the substation to perform switching operations, and switching actions can be performed much faster, which is a tremendous advantage in emergency situations.

A safer working environment is created for personnel, and huge production losses may be prevented. In addition, the operator or engineer at the SCADA terminal has a holistic overview of what is happening in the power network throughout the plant or factory, improving the quality of decision-making.

[For further description, please see the next parts of this series (Substation Automation)]


There are basic two varieties of open circuit breakers:

  1. DeadTank – compartment of circuit breaker, which is in earth potential.
  2. LiveTank – compartment of circuit breaker, which is in line potential.


SF6 Circuit Breaker

The structure of circuit breaker controls the techniques in which, the circuit breaker is putted up. This can be one of following ways.

1. Earth Mounting and Base Mounting: the major advantages of this sort of mounting are – ease, ease of formation, ease of protection and removal of support arrangements. An additional benefit is that in internal substations, there is lessening in the tallness of the structure. A weakness however is also and that to avoid risk to workers, the circuit breaker is enclosed by an earthed barricade, which raises the area requisite.

2. Retractable Breakers: these types of circuit breakers have the benefit of being gap saving owing to the actuality that isolators may be putted up in the same region of authorization that has to be permitted between the retractable circuit breaker as well as the live permanent links. Another benefit is that there is the simplicity and protection of preservation. Moreover such a mounting is inexpensive since at least two insulators for each phase are still desired to support the permanent circuit breaker plug links.


3. Suspended Breakers: at superior voltages tension insulators are more inexpensive than post or base insulators. Through this kind of mounting the live tank circuit breaker is balanced by tension insulators from transparency arrangements, and detained in a steady position by comparable insulators tensioned to the earth. There is the maintained benefit of cheap costs as well as simplified basics, and the arrangements used to hang up the circuit breakers can be used for additional functions.


Ashraful Huda

Electric Substation is the component of the electric power system as well as used for transmitting power from producing points to the load centers. Several of the vital components of a substation are:

1.   Busbars

2.   Lightning arrester or Surge arrestors

3.   Disconnecting Switches or Isolators

Varieties of Isolators:

i.            Central rotating

ii.            Centre-Break

iii.            Vertical swing

iv.            Pantograph type

4.   Earth Switch

5.   Current Transformer

6.   Voltage Transformer

7.   Circuit Breaker

Circuit Breaker Functions Include:

i.            Closing

ii.            Opening

iii.            Auto Re-closing

8.   Power Transformers

9.   Shunt Reactors

10.  Shunt Capacitor

11.  Series Capacitor

12. Series Reactors

13. Lightning Protection

14. Isolated Bus System (Phase)

15. Neutral Grounding Tools

16. Line Trap

17. Insulators

18. Power Cables

19. Control Cables

20. Relay, Control and Metering panels

21. Earthing System


The brief discussion about each individual component will be added very soon.