Effects of Electrical Faults on Switchboards

Electrical faults are directly proportional to the excessively high current flow in the circuit which causes damage to equipment and devices. Fault detection and analysis are necessary to select or design suitable switchgear equipment,?electromechanical relays, circuit breakers, and other protection devices.

There are mainly below types of faults in the electrical power system:-

1. Symmetrical Faults
2. Unsymmetrical Faults
3. Transient fault
4. Persistent fault
5. Bolted fault
6. Realistic faults
7. Arcing fault

We will discussion on the Causes of Electrical Faults in another upcoming article, here we will only discuss the effects of Electrical Faults and what are the protective equipment to prevent them.

• Overcurrent flow:?When a fault occurs it creates a very low impedance path for the current flow. This results in a very high current being drawn from the supply, causing the tripping of relays, and damaging insulation, and components of the equipment.
• Danger to operating personnel:?Fault occurrence can also cause shocks to individuals. The severity of the shock depends on the current and voltage at a fault location and even may lead to death.
• Loss of equipment:?Heavy current due to short circuit faults results in the components being burnt completely, leading to improper working of equipment or device. Sometimes heavy fire causes complete burnout of the equipment.
• Disturbs interconnected active circuits:?Faults not only affect the location at which they occur but also disturb the active interconnected circuits to the faulted line.
• Electrical fires:?A short circuit causes flashovers and sparks due to the ionization of air between two conducting paths which further leads to fire as we often observe in the news such as building and shopping complex fires.

It is possible to minimize causes like human errors, but not environmental changes. Fault clearing is a crucial task in the power system network. If we manage to disrupt or break the circuit when a fault arises, it reduces the considerable damage to the equipment and also property. Some of these fault-limiting devices include fuses,?circuit breakers, relays, etc.

1. Fuses:?It is the most common and primary protecting device. It is a thin wire enclosed in a casing or glass which connects two metal parts. This wire melts when excessive current flows in the circuit. The type of fuse depends on the voltage at which it is to operate. Manual replacement of wire is necessary once it blows out in case of ordinary fuses but if it is an HRC fuse then after blown off it will be replaced only.
2. Circuit breaker:?It makes the circuit at normal as well as breaks under abnormal conditions or during fault occurs. It causes automatic tripping of the circuit by disconnecting the supply of the main circuit through tripping devices in the auxiliary circuit when a fault occurs. It can be electromechanical circuit breakers like vacuum/oil circuit breakers etc., or?ultrafast electronic circuit breakers.
3. Relay:?It is a condition-based operating switch, in today’s scenario it’s microprocessor-based which can be programmed according to the application needs. It consists of a magnetic coil and normally open and closed contacts. Fault occurrence raises the current which energizes the relay coil, resulting in the contacts operating so the circuit is interrupted from the flowing of current.?Protective relays?are of different types like impedance relays, mho relays, etc.
4. Lighting power protection devices:?These include lighting arrestors and grounding devices to protect the system against lightning and surge voltages.

Above is a short story about the effects of electrical faults repercussions on a power system and little knowledge about the SCPD (Short Circuit Protection Devices) which will act as a safeguard at the time of Electrical Faults.