Free Expert Guides on Power Systems, Circuit Design & Electrical Troubleshooting

What is Lines or Feeder Protection?Transmission Line Protection DefinitionTransmission line protection is a set of strategies used to detect and isolate faults on power lines, ensuring system stability and reducing damage.Time Graded Over Current ProtectionThis may also be referred simply as over-current protection of electrical power transmission line. Let’ discuss different schemes of time graded over current protection.Protection of Radial FeederIn radial feeder, the power flows in one direct

Busbar Differential Protection DefinitionBusbar differential protection is a scheme that quickly isolates faults by comparing currents entering and leaving the busbar using Kirchoff’s current law.Current Differential ProtectionThe scheme of busbar protection, involves, Kirchoff’s current law, which states that, total current entering an electrical node is exactly equal to total current leaving the node.Hence, total current entering into a bus section is equal to total current leaving the bus sec

What is MPCB?MPCB DefinitionA motor protection circuit breaker (MPCB) is an advanced device designed to protect electric motors from electrical faults and overloads.Motor Protection Circuit Breaker Working Principle The motor protection circuit breaker can be considered a subtype of a thermal magnetic circuit breaker, but with additional functions that are specially designed to protect electric motors. The basic working principle is similar to all other circuit breakers. Thermal protection is us

Loss of Excitation DefinitionLoss of excitation in a generator occurs when the excitation system fails, causing the generator to run above synchronous speed.Induction Generator ModeWithout excitation, the generator becomes an induction generator, which can lead to overheating and overloading issues.Undercurrent Relay ProtectionAn undercurrent relay can protect against loss of field by operating when the excitation current falls below a certain value.This relay operates if the excitation current

Stator Earth Fault Protection DefinitionStator earth fault protection limits ground fault current to minimize damage to the stator core and winding.Ground Impedance RoleGrounding the stator with high impedance can reduce fault current but may lower relay sensitivity, requiring additional sensitive relays.Resistance Neutral EarthingIn this method, the stator’s neutral point is grounded through a resistor, which is connected with a current transformer and protective relay.Relay TypesDepending on t

Rotor Earth Fault Protection DefinitionRotor earth fault protection involves methods to detect and fix faults in the rotor’s field winding to prevent damage.Rotor Earth Fault Protection Types Potentiometer method AC injection method DC injection methodPotentiometer MethodThe scheme is very simple. Here, one resistor of suitable value is connected across the field winding as well as across exciter. The resistor is centrally tapped and connected to the ground via a voltage sensitive relay.As it is

What is Inter Turn Fault Protection?Inter Turn Fault DefinitionInter turn faults happen when the insulation between conductors in the same stator winding slot is damaged.Detection MethodsThese faults can be detected using stator differential protection or stator earth fault protection.Importance of Stator Inter Turn ProtectionHigh voltage generators and modern large generators need stator inter turn protection to prevent faults.Cross Differential MethodRoss differential methods is most common am

Motor protection setMotor protection is a set of devices and methods to protect a motor from failure and damage.Type of motor fault External motor fault Unbalanced supply voltage undervoltage Reverse phase sequence Loss of synchronizationInternal motor fault Bearing failure superheating Winding fault Ground faultMotor protection device Fuses: Fuses protect the motor by melting and interrupting the circuit during overload or short circuit. Circuit breaker: The circuit breaker can be reset after a

What is a Vacuum Switchgear?Vacuum Switchgear DefinitionVacuum switchgear is defined as a type of electrical switchgear that uses a vacuum as the arc quenching medium, providing high reliability and low maintenance.Dielectric StrengthFor a given contact gap, vacuum provides, about eight times more dielectric strength than air and four times more dielectric strength than SF6 gas at one bar. As the dielectric strength is so high, the contact gap of vacuum circuit breaker can be maintained very sma

What is Gas Insulated Switchgear?GIS DefinitionGas Insulated Switchgear is defined as a metal-enclosed switchgear that uses SF6 gas as the primary insulation between live parts and the earthed metal enclosure.Key components of a GIS include Circuit breakers Disconnectors Bus bars Transformers Earth switches Surge arrestersHigh Dielectric StrengthThe use of SF6 gas allows GIS to operate at higher voltages without breakdown, providing efficient and reliable power system management.Space Efficiency