Difference Between AC Contactor and DC Contactor
If you are a regular user of electrical appliances, power contactors are something you might have already heard of. They are electrical devices with the ability to switch electrical circuits on or off through a special relay.
Power contactors, as opposed to switches, are used for applications that carry higher volumes of current and are often equipped with multiple contacts, commonly used for electric motors.
Available in various types depending on their applications, features, and capabilities, power contactors can be primarily classified into - AC Contactor and DC Contactor. Though they both serve a common purpose, there are several differences between them.
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The major differences between AC contactors and DC contactors are as mentioned below:
- The primary difference lies in the construction of the contactors. The AC contactor contains a grid arc extinguishing device as opposed to the DC contactor, which has a magnetic arc extinguishing device.
- The AC contactor uses the principles of alternate current to operate and is equipped with an iron core that leads to eddy current loss and hysteresis loss. To prevent this, the iron core is laminated with silicon steel plates.
- As there is no generation or depletion of eddy current, DC contactors require no such lamination to counter the loss. The DC contactors can, therefore, be made out of complete cast steel or iron.
- The silicon steel plating in AC contactors is also required to prevent overheating. There is no heat generation when it comes to direct current, so the iron core in DC contactors needs no such lamination.
- The DC contactor has a U shape, while the AC contactor has an E shape.
- The DC contactor has a maximum operating frequency of 1200 times per hour. In contrast, AC contactors have a maximum operating frequency of 600 times per hour.
- The AC contactor is designed to work at lower resistances, so they have fewer turns. To counter the heat generation in AC contactors, the coils are made into thicker, yet smaller cylindrical shapes. These coils are provided with ample space in between to encourage heat dissipation.
- There is no inductance in DC contactors, so they can bear heavier resistance and more turns. As there is negligible heat generation, the coil in DC contactors can be tightly spun into a thinner cylindrical shape.
- The number of coils in AC contactors and DC contactors varies greatly. DC contactors have a significantly higher number of coils in comparison to AC contactors.
- The AC contactor and DC contactor can also be distinguished based on their construction. The DC contactor is equipped with a freewheeling diode.
- An AC contactor, on the other hand, does not employ the freewheeling diode structure. It uses the laminated iron core to maintain an efficient flow of electricity through the device.
- To be able to work efficiently, DC contactor electrical requires ample clearance around the equipment. AC contactors offer no such limitations.
Now that you know the main differences between AC contactor and DC contactor, you can decide more conveniently which one you require.
If you are looking to purchase AC contactors and DC contactors, you can easily avail them from the e-shop of Schneider Electric. Schneider Electric is a one-stop destination for all your electrical needs and wants!