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

What is a Varmeter?Varmeter DefinitionA varmeter is defined as an instrument used to measure the reactive power in an electrical circuit.Single Phase VarmeterIn single-phase varmeters, the pressure coil voltage leads the coil current by 90 degrees, and the reading represents the reactive power.Polyphase VarmeterPolyphase varmeters use two auto-transformers in an open delta configuration to create a phase shift for measuring reactive power.Reactive Power MeasurementReactive power is crucial to me

What is Voltmeter ?Voltmeter DefinitionA voltmeter is defined as an instrument that measures the voltage between two points in an electrical circuit.Working Principle of VoltmeterVoltmeters work by connecting in parallel to the circuit, using high resistance to measure voltage without significantly altering the circuit.Types of Voltmeters Parmanent Magnet Moving coil (PMMC) Voltmeter. Moving Iron (MI) Voltmeter. Electro Dynamometer Type Voltmeter. Rectifier Type Voltmeter Induction Type Voltmete

What is an Ammeter?Ammeter DefinitionAn ammeter is defined as a device that measures the electric current in a circuit in amperes.Working Principle of AmmeterAmmeters must have low resistance and inductive reactance to minimize voltage drop and power loss, and they are connected in series to measure current accurately.Classification or Types of Ammeter Permanent Magnet Moving Coil(PMMC) ammeter. Moving Iron (MI) Ammeter. Electrodynamometer type Ammeter. Rectifier type Ammeter.Permanent Magnet Mo

What is Megger ?Megger DefinitionA megger is defined as a device used to measure the insulation resistance of electrical components and systems, crucial for ensuring operational safety and functionality.Working PrincipleMeggers generate a testing voltage (either via a hand-cranked generator or battery) that creates a torque proportional to voltage and inversely proportional to current, helping measure the electrical resistance.Types of MeggersElectronicAdvantages Level of accuracy is very high.

What is a Backup Relay ?Backup Relay DefinitionA backup relay is an additional relay system that operates if the main relay fails, ensuring continued protection.Function of Backup RelayThe primary function of a backup relay is to trip the circuit breaker when the main relay fails.Reasons for Main Relay FailureMain relays can fail due to mechanical defects, power supply issues, or problems in the CT/PT circuits.Importance of Backup RelayBackup relays provide an extra layer of reliability, essenti

What is an Electromagnetic Relay ?Electromagnetic Relay DefinitionAn electromagnetic relay is a switch that uses an electromagnet to mechanically operate a switching operation, essential in various electrical protection systems.Operation PrinciplesThe working of electromagnetic relays involves principles like magnitude and ratio measurement, essential for understanding their functionality in electrical systems.Types of Relays Attracted Armature type relay Induction Disc type relay Induction Cup

What is Protective Relay ?Protective Relay DefinitionA protective relay is an automatic device that senses abnormal conditions in electrical circuits and triggers actions to isolate faults.Types of Protective Relays Definite time relays Inverse time relays with definite minimum time(IDMT) Instantaneous relays IDMT with inst Stepped characteristic Programmed switches Voltage restraint over current relayOperating PrinciplesProtective relays operate by detecting abnormal signals, with specific pick

What is Differential Relay?Differential Relay DefinitionA differential relay is defined as a device that responds to the difference between two or more similar electrical quantities, such as currents or voltages, to detect faults.Principle of OperationThese relays activate based on discrepancies in electrical quantities within the protected zone, ensuring accurate fault detection.Types and ConfigurationsDifferential relays vary mainly into current and voltage balance types, each tailored for spe

What is an Instantaneous Relay ?Instantaneous Relay DefinitionAn instantaneous relay is defined as a relay that operates with no intentional delay when the current exceeds a set threshold.No Intentional DelayInstantaneous relays activate without any added delay, making them very fast in operation.Inherent DelaysThese relays still have minor delays due to electrical and mechanical factors, but they are not intentionally introduced.Types of Instantaneous RelaysExamples include attracted armature r

What is a Thermal Relay?Thermal relay definitionA thermal relay is defined as a device that uses unequal expansion rates of metals in a bimetallic strip to detect overcurrent conditions.Working principleThermal relays work by heating a bimetallic strip, causing it to bend and close the normally open contact, which triggers the circuit breaker.Construction of thermal relayIt consists of a bimetallic strip, metal with different expansion coefficients, a heating coil and contacts.Technical paramete