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

Power System Protection DefinitionPower system protection is defined as the methods and technologies used to detect and isolate faults in an electrical power system to prevent damage to other parts of the system.Circuit BreakersThese devices are crucial for automatically disconnecting the faulted part of the system, ensuring the stability and safety of the remaining electrical grid.Protection RelaysProtection relays monitor the electrical network and initiate the tripping of circuit breakers whe

Backup Protection These over current and earth Fault relays may be of Inverse Definite Minimum Time (IDMT) or Definite Time type relays (DMT). Generally IDMT relays are connected to the in-feed side of the transformer.Overcurrent relays cannot differentiate between external short circuits, overloads, and internal faults of the transformer. Backup protection, using overcurrent and earth fault protection on the in-feed side, will activate for any of these faults.Backup protection is usually instal

What are Faults in Transformer?Definition of Transformer FaultsFaults in transformer refer to issues like insulation breakdowns and core faults that can occur inside or outside the transformer.External Faults in Power TransformerExternal Short Circuit of Power TransformerShort circuits can happen in two or three phases of the electrical power system. The fault current is usually high, depending on the short-circuited voltage and circuit impedance up to the fault point. This high fault current in

Capacitor Bank Protection DefinitionProtecting capacitor banks involves preventing internal and external faults to maintain functionality and safety.Element FusesManufacturers usually include built-in fuses in each capacitor element. If a fault occurs in an element, it is automatically disconnected from the rest of the unit. The unit can still function, but with reduced output. For smaller capacitor banks, only these built-in protection schemes are used to avoid the cost of additional protective

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