Get to Know about the Contactor’s Principle of Operation

An electrical switching device is an electric contactor. For switching an electrical circuit off and on, it is used. It is a special kind of relay, but between a relay and the contactor, there is a basic difference. In applications where higher current carrying capacity is involved, the contractor is mostly used while for lower current applications, the relays are used. Usually, multiple contacts are featured by these devices. The contacts provide operating power to the load and are mostly normally open whenever the contactor coil is powered. With electric motors, Contactors are popularly used.

There are different contactors types, and their own sets of capabilities, applications and features are present in the various types. Ranging from voltage from 25VDC to thousands of volts and a few to thousands of amperes, Contactors can take over a vast range of currents. Furthermore, in various sizes, these devices come. Measuring up to a meter or a yard on one side, they are small hand-held dimensions to large sizes.

With high-current load, a motor contactor is most commonly used because of its capability to handle high power well over 100kW and current well over 5000 amperes. They produce arcs when heavy motor currents are interrupted. To control and reduce these arcs, a contactor can be used.

Contactor’s Principle of Operation

The contactor’s operating principle is very simple; the electromagnet is energized by the current flowing through the contactor. A magnetic field is created by the energized electromagnet. The contactor core moves the armature as a result of this. Between the fixed and moving contacts, the circuit is then completed by a normally closed (NC) contact. This contact allows the current to pass to the load through the contacts.

The coil opens the circuit and is de-energized when the current is stopped from passing through. The contacts of contactors can close and open rapidly. Thus, larger loads can be handled by them. Moving contacts may bounce as magnetic contactor is designed to rapidly close and open contacts, as they rapidly collide with fixed contacts. In many contractors, Bifurcated contacts are used to avoid bouncing. Follow us on Facebook

Working and Characteristics of an Electrical Fuse

A fuse is an electric/electronic or mechanical device, which is generally used to protect circuits from overloading, the excessive current which then makes sure the protection of the circuit. There are different electrical fuse manufacturer and types of fuses, but their function is the same. Here we will discuss its construction, working, and characteristics.

Working and Construction of a Fuse

A general fuse consists of a low resistance metallic wire that is enclosed in a non-combustible material. It is used for connection and installation in series with a circuit and device which then needs to be protected from short circuit and over current. If it is not done then in the absence of the fuse, circuit breaker, and arrester disconnector, the electrical appliance may get damaged as they are unable to handle the excessive current according to their rating limits

The thin wire inside the fuse melts whenever a short circuit, over current or mismatched load connection, occurs and it is due to the heat generated by the heavy current flowing through it. Therefore, from the connected system, it disconnects the power supply. Fuse wire is just a very low resistance component in the normal operation of the circuit and it does not affect the normal operation of the system connected to the power supply.

Characteristics of a Fuse

• Breaking Capacity of a Fuse
• Current Carrying Capacity of Fuse and its fuse
• I2t Value of Fuse
• Response Characteristic of a Fuse
• Response Characteristic
• Rated voltage of Fuse
• Voltage Rating of Fuse

Packaging Size

On the amount of current flowing through its wire the speed at which the fuse blows rely on. The response time will be faster if the current flowing through the wire is higher.

For an overcurrent event response, the characteristic shows the response time. Ultra-fast fuses or Fast fuses are the types of fuses that respond rapidly to the current situation. In many semiconductor devices, they are used as semiconductor devices are damaged by overcurrent very rapidly.

There is another fuse which is called a slow burn fuse. To the overcurrent event, this 24kv drop out fuse does not respond instantly but after several seconds of over-current occurrence, it blows. In motor control electronics systems such fuses found their application and it is because motors take a lot more current at starting than running. Follow us on Twitter