Differential Protection Relay

Definition: The relay whose operation depends on the phase difference of two or more electrical quantities is known as the differential protection relay. It works on the principle of comparison between the phase angle and the magnitude of the same electrical quantities. For example: Consider the comparison of the input and output current of the …

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Mho Relay

A mho Relay is a high-speed relay and is also known as the admittance relay. In this relay operating torque is obtained by the volt-amperes element and the controlling element is developed due to the voltage element. It means a mho relay is a voltage controlled directional relay. A mho relay using the induction cup structure …

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Reactance Relay

The reactance relay is a high-speed relay. This relay consists of two elements an overcurrent element and a current-voltage directional element. The current element developed positive torque and a current-voltage developed directional element which opposes the current element depending on the phase angle between current and voltage. Reactance relay is an overcurrent relay with directional …

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Classification of Substations

The substation is the medium of transferring the power from generating unit to the consumer end. It consists different types of equipment like transformer, generator, power cable which helps in the power transmission. The generation, transmission and distribution are the main work of the substation. The substation which generates the power is known as the …

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Impedance Type Distance Relay

Definition: The relay whose working depends on the distance between the impedance of the faulty section and the position on which relay installed is known as the impedance relay or distance relay. It is a voltage controlled equipment. The relay measures the impedance of the faulty point, if the impedance is less than the impedance …

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Distance Protection Relay

Distance protection relay is the name given to the protection, whose action depends on the distance of the feeding point to the fault. The time of operation of such protection is a function of the ratio of voltage and current, i.e., impedance. This impedance between the relay and the fault depends on the electrical distance …

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Overcurrent Relay

Definition: The overcurrent relay is defined as the relay, which operates only when the value of the current is greater than the relay setting time. It protects the equipment of the power system from the fault current. Depending on the time of operation the overcurrent relay is categorized into following types.  Instantaneous Overcurrent relay Inverse …

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Thermal Relay

The thermal relay works on the principle of the thermal effect of electrical energy. The bimetallic strips, heating coils and the current transformers are the important parts of the thermal relay. The current transformer supplies the current to the coils of the heater. The thermal energy of the heater coils heated the bimetallic strips. The …

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Types of Relays

The relay may be defined as an electrical device interposed between the main circuit and the circuit breaker in such a manner that any abnormality in the circuit acts on the relay, which in turn if the fault is dangerous then it causes the circuit breaker to isolate and so to remove the faulty element. …

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Protective Relays

Protective relay work as a sensing device, it senses the fault, then known its position and finally, it gives the tripping command to the circuit breaker. The circuit breaker after taking the command from the protective relay, disconnect the faulted element. By clearing the fault fast with the help of fast-acting protective relay and associated …

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