1. The series and parallel connection application of contactors Many electrical equipment are single-phase loads, so several poles of multi-pole contactors can be used in parallel. Such as resistance furnaces, 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 after parallel connection is not completely proportional to the number of poles in parallel. This is due to the fact that the resistance values of the active and static contact circuits are not necessarily completely equal, so that the current flowing through the active contacts is not evenly distributed. Therefore, the current can only be increased to 1.8 times after the parallel connection of two discontinuations, and the current can only be increased to 2-2.4 times after the parallel connection of the three poles.
In addition, the demand points out that since it is impossible to turn on and off the contacts at all poles after parallel connection, it is not possible to make and break the ability to progress.
Sometimes, several poles of the contactor can be used in series, and the arc can be divided into many segments due to the increase of contact breakage, which improves the arc extinguishing ability and accelerates the extinguishing of the arc. Therefore, several poles can be connected in series to improve their operating voltage, but not exceed the additional insulation voltage of the contactor. The agreed heating current and additional working current of the contactor in series will not change.
2. The influence of power supply frequency Regarding the main circuit, the change of frequency affects the skin effect, and the skin effect increases when the frequency is high, and for most products, 50 Hz and 60 Hz have little impact on the temperature rise of the conductive circuit. However, as far as the lead coil is concerned, it should be noted that the magnetic flux of the magnet wire used in the 50 Hz planning for the magnet wire at 60 Hz will be reduced, and whether it can be used depends on the margin of the plan. In general, it is best for the user to use according to its calibration value, and order according to the operating power frequency used.
3. The influence of the operating frequency The number of operating cycles per hour of the contactor has a great impact on the burning loss of the contact, and attention should be paid to the selection, and 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 the given value, the contactor must be degraded.
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