Little knowledge about DC contactor

Update:11-12-2020
Summary:

The DC contactor adopts a modular design, which can ass […]

The DC contactor adopts a modular design, which can assemble the number of contacts required by the customer and the contact form (normally open, normally closed and conversion) required by the customer with the least parts; the series of products have high contact breaking voltage , And adopts horizontal blowing magnetic field to extinguish the arc, the highest breaking voltage can reach 220VDC. The product is suitable for program-controlled power supply or uninterruptible power supply system, forklift, electric vehicle, engineering machinery system.
Advantages of  DC Immunity Current Transformers:
1. Reliable airtightness allows the product to be used for a long time in harsh and explosion-proof environments, and its internal components such as coils and contacts are not oxidized. At the same time, the product has the advantages of low energy consumption, low heat generation, long life, small size, light weight, etc. .
2. Can control high voltage and high current
3. Energy saving Some products of specifications adopt energy saving board.
4. A smaller arc makes the product more effective and safer in use. The inert gas is used to seal, so that there is basically no arc between the contacts when the product is in action, and the magnetic blow-out arc is used to ensure safety.
5. High stability The internal mechanism and structure are completely sealed in inert gas, free from interference from external adverse factors, and the contact resistance remains stable for a long time.
6. Wide range of applications. Applications include: DC power control, battery switch control, circuit safety protection, etc.
Working principle of DC contactor:
When the contactor coil is energized, the coil current generates a magnetic field, which makes the static iron core generate electromagnetic attraction to attract the moving iron core and drive the AC contactor
Contact action: normally closed contact is disconnected, normally open contact is closed, the two are linked. When the coil is de-energized, the electromagnetic attraction disappears, and the armature is released under the action of the release spring to restore the contacts: the normally open contact is disconnected, and the normally closed contact is closed

Selection method of DC contactor:
1. Choosing the type of DC contactorThe type of DC contactor should be selected according to the type of load current and the weight of the load, that is, whether it is an AC load or a DC load, light load, general load or heavy load.
2. The rated current of the main contact of the DC contactor The rated current of the main contact of the DC contactor can be calculated according to the empirical formula. IN main contact≥PN motor/(1~1.4)UN motor If the motor controlled by the DC contactor starts, brakes or Frequent reversals, generally reduce the rated current of the main contact of the contactor by one level.
3. Rated voltage of the main contactThe voltage marked on the nameplate of the contactor refers to the rated voltage that the main contact can withstand, not the voltage of the attracting coil.The rated voltage of the main contact of the contactor should not be less than the rated voltage of the load during use.
4. The selection of operating frequency The operating frequency refers to the number of on-offs per hour of the contactor. When the on-off current is large and the on-off frequency is too high, it will cause severe overheating of the contacts and even welding. If the operating frequency exceeds the specified value, it should be Choose a DC contactor with a rated current one level higher.
5. Selection of the rated voltage of the coil The rated voltage of the coil is not necessarily equal to the rated voltage of the main contact. When the circuit is simple and there are few electrical appliances, you can directly choose the voltage of 380V or 220V. Voltage (in 1964, the international regulation is 36V, 110V, or 127V) coil.