Difference between Short circuit and overload
Short Circuit A short circuit occurs when two or more current carrying conductors of different phases or different voltage levels or different terminal (in DC circuits) come in contact with…
Miniature Circuit Breaker (MCB) – Principle of operation
Miniature circuit breakers commonly known as MCB, are mechanically operated switches cum circuit protection devices. It is an electro-mechanically operated automatic circuit protection devices. An MCB is used to interrupt a circuit during overload and short circuits. It can be used as an alternative to fuses for domestic applications. The advantage of MCBs over fuses is that MCBs are reusable even after interruption of the circuit after an overload or short circuit. Moreover, MCBs are more sensitive to faults than fuses. (more…)
Difference between MCB, MCCB, RCCB, RCBO and Isolator
Introduction
Circuit breakers are safety devices, which ensures the safety of equipment and personnel from electric shocks and damages. They are self-acting and should safely interrupt the current flow on the event of faults. Circuit breakers are a cost-effective and efficient alternative to traditional circuit protection fuses. These devices are reusable and may help in saving a lot of money and downtime. (more…)
Difference between circuit breaker and isolator
Isolator/ Disconnectors
Isolator or disconnectors, as the name indicates, is a switching or isolation device, intended to disconnect an equipment or electrical Circuit from the supply. It is an offload device, which means it can be operated only when the current passing through it is zero. Unlike circuit breakers, it lacks a built-in arc suppression system. It can be operated only during offload conditions. (more…)
What is meant by B, C, D, K and Z curves in MCBs?
MCB (Miniature circuit breaker) is a device designed to protect a circuit from short circuits and overcurrents. Trip curves of MCB’s (B, C, D, K and Z curves) tell us about the trip current rating of Miniature Circuit breakers. Trip current rating is the minimum at which the MCB will trip instantaneously. It is required that the trip current must persist for 0.1s.
Difference between MCB and RCBO
MCB – Miniature Circuit Breaker and RCBO – Residual Current Circuit Breaker with Overload Protection are circuit protection devices. These devices are commonly used in low voltage power distribution and can be seen in distribution boards in homes, offices, commercial buildings etc.
Buchholz Relay | Buchholz relay – Principle of operation
In large oil immersed transformers, we can find a cylindrical object installed in the pipe connecting the conservator to the main tank. This cylindrical object, that looks like a solenoid valve is called Buchholz relay. It is a type of oil activated relays. It can be found in all oil immersed transformers rated higher than 500kva. (more…)
Sizing of contactor and overload relay for 3 Phase DOL starter
Data required for selection of DOL starter
- KW rating of motor
- Operating voltage
- Application
- KVA code if available
Asynchronous motor(Induction Motor) Starters | Comparison of induction motor starters
As the name indicates, starters are used to start or stop a motor. It consists of an electromechanical switch and protection devices (overload and/or short-circuit protection).
Why should we need a starter?
Contactor – Construction, Operation, Application and Selection
Contactor- Construction, Working Principle, Application
An electrical contactor is a switching device, widely used for the switching of motors, capacitors (for power factor correction) and lights. As the name indicates contactor are used to make or break contacts as like an ordinary on-off switch. The only difference is that the contactors have an electromagnet that holds the contacts when energized whereas switches do not have it.
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