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First, the magnetic holding relay working principle and influence under the constant magnetic field The magnetic holding relay is mainly composed of three parts: the coil, the armature assembly, and the moving and static film. The magnetic force generated when the coil is energized drives the change of the direction of the armature assembly, thereby changing the action of the moving and static film. The opening and closing. Under the influence of the constant magnetic field, the magnetic force generated by the coil will be cancelled out, which will cause the relay to behave simply or not at the same driving voltage. At the same time, the state of the armature assembly may be changed and the relay may malfunction.
Second, the analysis of the constant magnetic standard The new specification specifies that the magnet's volume is 50mm*50mm*50mm, and the magnetic force is 200mT (single-phase electricity meter) and 300mT (three-phase electricity meter). Under normal conditions, the magnetization is not uniform, and the magnetic force distribution on the surface of the magnet is small in the middle and large in the circumference. Therefore, the magnet used in the design of the anti-magnetism product should have a center magnetic field of 200mT or 300mT, leaving a margin.
Third, the impact of anti-magnetic design factors 1, the coil power to ensure that enough drive is not offset by the magnet to properly drive the relay, coil power needs to be properly increased, the need to adjust the wire diameter and the number of ampere wire, at the same time The limitation of the relay product's external dimensions, the space that can be wound is relatively limited, and it needs to be calculated more rationally during design.
2. The magnetic force of the armature assembly ensures that the state of the armature assembly does not change under the influence of the external magnetic field, and the magnetic force of the armature assembly needs to be properly increased to provide sufficient magnetic retention force, but at the same time, the magnetic force generated by the coil is also affected by the external magnetic field. It will be reduced, so when designing, it is necessary to ensure the fit of the armature assembly and the coil without reducing the holding force.
3, contact pressure enough contact pressure can reduce the contact resistance, thereby reducing the temperature rise of the relay power state, at the same time, can also be in the short-circuit current impact, the contact will not be opened to ensure that the contact is complete and the relay does not explode . However, in the course of the magnetic force reduction of the coil and the magnetic force adjustment of the armature assembly, the contact pressure is too large to be normally opened and closed. Therefore, in the design, it is necessary to ensure that the contact pressure is sufficient and the relay can be operated normally. , need to adjust the mold and related parameters to achieve this purpose.
4. The shielding shell of the shielding shell can cancel out part of the magnetic force of the external magnetic field and reduce the influence of the external magnetic field on the relay. At the same time, however, the shielding shell will also guide the magnetic force generated by the coil, which will negatively affect the action of the relay. Therefore, in the design, the size and position of the shield shell can not be changed, you need to consider adjusting the internal parameters of the relay to match the impact of the shield on the performance of the relay.
Fourth, the anti-magnetism product design misunderstanding Because the magnetic holding relay works by the magnetic steel as the rotating mechanism, by the coil magnetic force to change the open and close the state, and shielding the iron shell will also have an impact on this state, plus On the external constant magnetic field interference, often in the design of the structure, have to sacrifice some performance parameters to meet the flexibility of the relay action, but reduce the reliability.
The increased coil power consumption is limited by the size of the relay, and is limited by the drive voltage of the meter solution. Therefore, when the coil power consumption design is limited, the magnetic force of the armature assembly is often reduced, and the closing pressure between the contacts is decreased. In order to make the relay work more easily, the temperature rise of the relay, the ability to withstand short-circuit currents, and the magnetic holding force are reduced, and it is difficult to find in general routine tests.
Fifth, need to pay attention to the main parameters of anti-ferromagnetic products compared with ordinary products 1, magnetic armature magnet assembly armature components determine the magnetic holding relay magnetic retention, performance in the transport of the bump is not easy to make the state change, in the outside world Under a constant magnetic field disturbance, the state is not easily changed, so the armature assembly magnetic force of the anti-magnetism product should not be smaller than the ordinary product.
2. When the pressure of the contact closure pressure is too high, in the adjustment of the anti-ferromagnetic product parameters, it may cause the relay to be opened or closed. Therefore, in the anti-magnetic product design, the contact pressure should not be lower than the normal product. small.
3, with shielded iron shell before and after the action voltage increases the amplitude of the shielding shell will guide the magnetic force generated by the coil, so that the relay action is not crisp or not action, when the coil power consumption is limited, it will reduce the magnetism of the armature assembly, you can The lower voltage than the original is driven by the coil. At this time, the parameters of the coil part before the shielded shell, the operating voltage is very low (30% of the rated voltage), with a shielded shell, the action voltage rises significantly (up to 60% or even more than 70%). Therefore, in the parameter adjustment before and after the shielded shell, it is necessary to ensure that the magnitude of the change in the operating voltage should not be too large, so as to ensure the reliability of the product. 