AC contactors are divided into AC contactors (working voltage AC) and DC contactors (voltage DC), which are used in power engineering, power distribution equipment and power engineering places. AC contactor theoretically refers to a household appliance that uses a coil to form an electromagnetic field according to the amount of industrial production current to turn off the AC contactor to control the load.
AC contactor is a power switch and control circuit commonly used as a switching power supply. It uses the main contact surface to turn on and off the power circuit, and uses the auxiliary contact surface to implement program control. The main contact surface generally only has the opening and closing contact surfaces, and the auxiliary contact surface usually has two pairs of contact surfaces with the functions of opening and closing and normally closed. Small AC contactors are usually used as small relays and main power circuits. The contact surface of the AC contactor is made of silver-tungsten alloy, which has good electrical conductivity and thermal crack resistance.
A DC contactor is an AC contactor used in a DC circuit. It matches the AC contactor and usually has a main contact surface. Assist with contact surfaces and coil contact points. Take the DC contactor shown in the image as an example. It adopts modularization and can assemble the touch routines and touch methods required by customers (often turned on, often turned off and changed); this product series has a high touch power switch operating voltage and level blowing electromagnetic field arc extinguishing , the maximum power switch operating voltage can be achieved 220VDC. This product is suitable for system control switching power supply or ups power system software, electric forklift, new energy electric vehicle construction machinery equipment system software.
The structural features and principles of DC contactors are basically the same as those of AC contactors, and they are also composed of electromagnetic induction organization, touch system software and arc extinguishing equipment, but the electromagnetic induction organization is different.
Generally speaking, the difference between the structure of DC contactor and AC contactor depends on: the iron core coil is not easy to cause eddy and eddy current loss damage according to the DC power supply, so it is not easy to get hot. In order to better facilitate production and processing, the iron core is made of all mild steel. In order to better make the coil heat dissipation excellent, the coil is usually wound into a thin cylindrical shape, which directly contacts the iron core, which is very easy to heat dissipation. Let’s take a look at the four differences between DC contactors and AC contactors.
The key difference is the AC contactor and the DC contactor.
1. The iron core is different: the iron core of the AC contactor will cause eddy and eddy current loss damage, while the DC contactor has no iron core damage. Therefore, the iron core of the AC contactor is composed of silicon steel plates with mutually insulating layers, usually E-shaped; the iron core of the DC contactor is made of all mild steel, most of which are U-shaped.
2. The software of the arc extinguishing system is different: the grid arc extinguishing equipment is selected for the AC contactor, and the magnetic blowing arc extinguishing device is selected for the DC contactor.
3. The number of coil turns is different: the number of coil turns of the AC contactor is small, the number of turns of the DC contactor coil is more common in the DC power supply, the AC contactor is divided into an AC circuit, and the DC contactor is divided into a DC circuit.
4. The actual operating frequency is different: the AC contactor has a large operating current, the maximum is 600 times/hour, and the application is low-cost. The DC contactor can reach 2000 times/hour, and the application cost is relatively high.
Can AC contactors and DC contactors be interchanged?
1. The AC contactor can be applied to the DC contactor in an emergency, and the pull-in time cannot exceed 2 hours (because the heat dissipation of the AC coil is worse than that of the DC, which lies in its different structure). It is best to connect the resistance in series with the AC coil, but DC cannot replace the AC contactor;
2. The number of turns of the AC contactor coil is small, and the number of turns of the DC contactor coil is large. When the current of the main power circuit is too large (IE250A), the AC contactor uses a series-connected double-winding coil;
3. The DC relay coil resistor is large and the current is small. If it is not easily destroyed by connecting to AC power, please place it immediately. However, the AC automobile relay coil has a small resistor and a large amount of current. If it is connected to a DC regulated power supply, the coil will be destroyed;
4. The number of turns of the AC contactor coil is small and the resistor is small. When the coil enters the alternating current, there will be a large magnetic induction friction resistance, which far exceeds the resistance of the coil. The key to the excitation power of the coil is the size of the magnetic induction friction resistance. If a DC current were to flow in, the coil would become a purely resistive load. At this time, the amount of current passing through the coil will be particularly large, making the coil hot or even burnt. Therefore, AC contactors cannot be used as DC contactors.
Post time: Apr-30-2022
