AC contactor selection method - Solutions - Huaqiang Electronic Network

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

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1. Series and Parallel Use of Contactors There are many consumers that use single-phase loads. Therefore, several poles of multi-pole contactors can be used in parallel. Such as resistance furnaces, electric welding transformers, etc. When using several poles in parallel, a smaller capacity contactor can be used. However, it must be noted that the agreed heating current of the contactor in parallel is not completely proportional to the number of poles connected in parallel. This is because the resistance values ​​of the active and static contact loops are not necessarily equal, so that the positive current flowing through is not evenly distributed. Therefore, the current can only be increased to 1.8 times after the parallel connection, and the current can only be increased to 2 to 2.4 times after the three poles are connected in parallel.
In addition, it should be noted that since the pole contacts after the parallel connection cannot be turned on and off at the same time, the turn-on and turn-off capabilities cannot be improved.
Sometimes, several poles of the contactor can be used in series, and the arc can be divided into a plurality of segments due to the increase of the contact fracture, which improves the arc extinguishing ability and accelerates the extinction of the arc. Therefore, after several poles are connected in series, the operating voltage can be increased, but the rated insulation voltage of the contactor cannot be exceeded. The agreed heating current and rated operating current of the contactors after series connection do not change.
2. Influence of power frequency For the main circuit, the frequency change affects the skin effect, and the skin effect increases when the frequency is high. For most products, the temperature rise of the conductive circuit is not very high for 50 Hz and 60 Hz. Big. However, it is necessary to pay attention to the attracting coil. When the attracting coil of the 50 Hz design is used for 60 Hz, the magnetic flux of the electromagnetic wire will be reduced, the suction force will also be reduced, and whether the margin of the design is used can be used. Under normal circumstances, the user is best to use according to its calibration value, ordering according to the operating power frequency used.
3. Influence of operating frequency The number of operating cycles per hour of contactor has a great influence on the burning loss of the contact. It should be noted when selecting. The applicable operating frequency is given in the technical parameters of the contactor. When the actual operating frequency of the electrical equipment is higher than a given value, the contactor must be derated.