The Various Forms Of Contactors And How They Operate

DC contactor suppliers

Even though technology has advanced over time, the fundamental techniques for managing electrical circuits have not changed. One of these is a contactor, and this article looks at the many high voltage DC contactor kinds and how they operate. Additionally, it examines the variations between AC and DC contactors as well as contactor and relay.

How Do Contactors Work?

An electromechanical switch called a contactor establishes or breaks the electrical connection between the power source and the load. The switched circuit is often powered at a considerably higher level than the contactor, which is electrically regulated. For instance, you may have a 230-volt motor switch controlled by a 230-volt coil magnetic.

Types of Contactors

Controlling electric motors, thermal evaporators, lights, capacitor banks, heating, and other electrical loads are among the uses for contractors. Both the size and capacity of contractors vary. Large ones measure approximately a meter on the side and those are readily lifted with one hand. Additionally, there are some with breaking currents between a few and hundreds of amps as well as those with voltages ranging from 24 V DC to several kilovolts.

Knife Blade Switch

It utilizes ON and OFF electric motors and is the first form of contactor. A strip and a lever made up the switch for the knife blade. This contactor is operated manually as a result of the lever’s function to raise and lower the metal strip. It was no longer used because of several flaws. These difficulties include

  • A contactor’s lifespan was shortened due to frequent arcing.
  • had potential dangers.
  • Being susceptible to mud and moisture.

Manual Double Break Contactor

The knife blade switch was replaced with and improved upon using this contactor. However, manual operation is still a part of it. Other crucial characteristics include

  • Double break contacts allow for the simultaneous opening of two circuits, increasing current flow in constrained areas.
  • Unit with proper enclosure guarding the inside.
  • Improved operation.
  • Reduced size.

What Functions of a Contactor Device?

You must be familiar with the many components of a contactor to comprehend how it functions. Three things are necessary to consider for high voltage DC contactor suppliers in China;

  • The electromagnetic coil.
  • Contacts.
  • The enclosure or frame.

An electromagnet or a coil

The driving force of a contactor that closes the contacts is provided by the coil. It functions like an electromagnet because it has a coil twisted around an electromagnetic core. The coil consists of two parts: a fixed component and a moveable part, connected by a spring. This structure creates a mechanism for spring returns.

The moveable component is attached to a rod known as an armature. Both contacts are in connection when the coil’s force is greater than the spring’s force. The contacts disengage when the spring’s force is greater than the coil’s force.


The contactor coil’s input can be either AC or DC. The electromagnetic core is excited by this current, which originates from the contactor’s external control circuit. Soft laminated iron serves as the electromagnetic core of AC contactors. It lessens the loss due to eddy currents. Since eddy current is not a problem with DC contactors, solid steel is used for the electromagnetic core.

In a contactor, contacts are responsible for transporting current. A contactor has three distinct sorts of contacts: auxiliary contact, power contact, and contact spring. There are two different kinds of power contacts: fixed and moving contact.

High welding resistance and consistent arc resistance are required for contact material. Additionally, the substance must be resistant to mechanical stress and erosion. Silver tin oxide is the material useful in high-current and DC applications, whereas silver nickel and silver cadmium oxide are useful in low-current applications.


The enclosure serves to safeguard the contactor’s interior components, as its name indicates. It protects the contacts from oil, explosive risks, dust, and bad weather. Additionally, it stops employees from touching the contacts.


In a nutshell, the contactor operates as follows:

The electromagnetic core is excited by the current that travels via the contactor from the external control circuit. A magnetic field produced by the coil/electromagnet then causes the contactor to move the armature. The circuit between the fixed and movable contacts is subsequently completed by a usually closed contact. These connections then allow the electricity to flow to the load.

The coil de-energizes when the current is cut off, and the magnetic force zeroes out. Due to the increase in the pressure of spring force, the armature is pulled back, which completes the circuit. Contactors’ construction makes quick ON-OFF action possible.

DC contactor and AC Contactor Differences

There are five key ways in which an AC contactor differs from a DC contactor;

  • The electromagnetic core of a DC contactor consist of soft steel, whereas the core of an AC contactor depends on laminated silicon steel sheets.
  • A DC contactor’s electromagnetic core frequently has a U form, whereas an AC contactor’s electromagnetic core frequently has an E shape.
  • At the static core’s end of an AC contactor is a short circuit ring. It reduces the electromagnet’s vibration and noise. Since it is not necessary, a DC contactor does not come with a short circuit ring.
  • An AC contactor may operate at a maximum frequency of 600 times per hour and have a high beginning current.
  • While an AC contactor utilizes a grid arc as an extinguishing mechanism, a DC contactor uses a magnetic quenching arc.


High voltage DC contactor have additional safety features and are essential tools for controlling a circuit. Finding an electrical device that meets your demands and performs as intended is crucial, just as with any other electrical item.

You also need a dependable vendor, China DC contactor manufacturers, that provides authentic goods that adhere to international standards like IEC. You also want additional design and utility options, as well as expert assistance. These elements assist you in choosing a useful device that enhances safety and offers you value for your money.

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