China Nanfeng Electric


DC contactors Profile

DC contactor

1 DC contactor Introduction              2  DC contactor selection method    

3 contactor working principle           4  contactor exchange difference   

5 contactor  overcurrent fault           6   contactor selection of attention

1 DC contactor Introduction

The contactor adopts modular design, can with minimal parts assembly customer required number of contacts and clients need contact form (normally open, normally closed and conversion). The series products contact breaking high voltage, and the transverse blowing magnetic field quenching, the maximum open circuit voltage can be reached 220VDC. products applicable to the programmable power supply or uninterrupted power supply system, forklifts, electric vehicles, engineering machinery system.

2 DC contactor selection method

Selection method of DC contactor.

1 select the type of DC contactor type DC contactor type should be based on the type of load current and load of light weight to choose, that is AC or DC load, is light load, general load or heavy load.

2. DC contactor main contact rated current DC contactor main contact rated current can be calculated according to the empirical formula in the main contact is more than or equal to PN motor / (1~1.4) UN motor if DC contactor control motor starting, braking or reversal frequently in general will be the main contact of the contactor's rated current drop level using

3. Main contact rated voltage of the contactor nameplate standard voltage refers to the rated voltage of the main contact can withstand, not attracted to the coil voltage and use main contacts of the contactor's rated voltage should be not less than the rated voltage of load.

4. The operating frequency of the choice of operating frequency refers to the contactor per hour on-off times. When the on-off current is large and the on-off frequency is too high, causing the contact seriously overheating, even welding. Operating frequency if more than set value, should choose the rated current of a DC contactor.

The rated voltage of the 5 coil is not necessarily equal to the rated voltage of the main contact, when the circuit is simple, the use of electrical appliances less, can be directly used 380V or 220V voltage, such as circuit complexity, the use of electrical appliances over 5h, 24V, 48V or 110V voltage (1964 International regulations for 36V, 110V, or 127V) of the coil.

3 Contactor working principle

When the contactor coil is energized, the coil current generates a magnetic field, which causes the static core to generate electromagnetic suction to attract the moving core, and drives

AC contactor

Contact action: normally closed contact is disconnected, normally open contact is closed, the two are linked. When the coil power, the electromagnetic force disappears, the armature of the release spring release, make contact restoration: normally open contact is disconnected, the normally closed contact closure

4 Contactor exchange difference

DC contactor, the main circuit current is dc.

AC contactor, the main circuit of the current is the exchange of.

5 Contactor overcurrent fault

The overcurrent fault can be divided into acceleration, deceleration, and constant velocity. It may be due to the increase of the frequency converter of the time is too short, load, load distribution, output short circuit, etc.. At this time, the general can be extended by the time to increase the deceleration time, reduce the load of the mutation, plus energy consumption brake components, load distribution design, the line for inspection. If you disconnect the load frequency converter or the fault of the inverter, the inverter inverter circuit is bad, need to replace the inverter.

Overload fault

The overload fault includes the frequency conversion and the motor overload. The acceleration time is too short, the grid voltage is too low, the load is too heavy, and so on. Generally by the extension of the time, the extension of the brake time, check the grid voltage, etc.. Load is too heavy, the selected motor and inverter can not drag the load, it may be due to mechanical lubrication is not good cause. If the former is to replace the large power of the motor and frequency converter; if the latter to the production machinery maintenance.

Fault summary

1, in a word, in the design, installation, use of frequency converter must comply with the instructions of the use of inverter manual;

2, the electrical design personnel, on-site electrical commissioning staff can improve the reference of this converter.

6 selection of attention

The action principle of DC contactor is similar to that of AC contactor, but the magnetic field energy stored in the inductive load is instantaneous released and the high energy arc generated at the breakpoint. In the medium / large capacity DC contactor, the whole structure is arranged in a single point plane, which is characterized by a long arc distance, and an arc extinction cover. Small capacity DC contactor with double break point cubic layout structure.

Select the contactor should pay attention to the following points.

Rated voltage rated voltage is greater than or equal to 1, the main contact load.

The rated current is more than 2, the main contact of 1.3 times the rated current of the load.

3, coil rated voltage. When the line is simple, the use of electrical appliances less, can choose 220V or 380V; when the circuit is complex, the use of electrical appliances more or less safe place, can choose 36V, 110V or 127V.

4, the number of contacts, the type should meet the requirements of the control line.

5, operating frequency (per hour contact number of times). When the current is larger and the breaking frequency exceeds the specified value, the rated current should be used for the first time. Otherwise it will make the contact severe fever, even welded together, resulting in motor load phase operation.

Zhejiang Nanfeng Electric Appliance Co., Ltd.

Address: No.43,Daqiao Road,Liushi Town,Yueqing City, Zhejiang Province,China.
Tel: +86-577-62797256 62776658
Fax : 86-577-62797257

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