Common fault types and diagnostic methods of relays

First, the contact is loose and cracked back

The contact is the electrical contact part of the relay to complete the switching load. The contacts of some products are press-fitted by riveting. The main disadvantages are loose contact, cracked contact or excessive positional deviation. This will affect the contact reliability of the relay.

The loosening of the erasing point occurs, which is caused by an unreasonable size of the mating portion of the reed and the contact or an improper adjustment of the riveting pressure by the operator.

Contact cracking is caused by excessive material hardness or too much pressure. For different materials, the contacts are made of different materials. Some of the higher hardness contact materials should be annealed for contact manufacturing, riveting or spot welding.

The manufacturing of the contacts should be careful. Since the materials have tolerances, the length of each cut should be determined after trial and error. Contact manufacturing should not result in flash, padding and underfill.

The contact riveting is caused by the operator not correcting the touch and misaligning the upper and lower touches. Contact damage, contamination, oil contamination and iron filings on uncleaned tools.

Relevant person summary:

Contact corrosion.

The load of the contact switching is mostly inductive. When the inductive load is disconnected, the accumulated magnetic energy will generate a high back potential at both ends of the contact, and the air gap between the contacts will form a spark, causing electrical erosion. The contact surface is recessed, causing poor contact, or the two contacts are stuck together and cannot be separated, thereby causing a short circuit. Preventing the electrical corrosion between the contacts can be achieved by setting the resistance fire extinguishing circuit and setting the resistance and extinguishing circuit.

The contacts are dusty.

Dust and dirt will deposit on the contacts of the relay, which will cause a black oxide film on the contact surface, resulting in poor contact of the relay. Therefore, it is necessary to clean the contacts regularly, and carbon tetrachloride liquid can be used. Ensure good contact performance of the contacts.

Second, the relay parameters are unstable

A considerable part of the components of the electromagnetic relay is riveted and fitted, and the main problem is that the riveting is loose or the bonding strength is poor. This kind of fault will make the relay parameters unstable, the parameters change greatly under high and low temperature, and the mechanical vibration and impact resistance are poor. The main cause of this problem is the poor condition of the riveting parts, the improper placement of the parts, the unqualified quality of the work tools or the inaccurate installation. Therefore, it is necessary to carefully check whether the tool and the rivet parts meet the requirements before the welding.

Third, electromagnetic system riveting deformation

After the riveting, the parts are bent, skewed, and the pier is thick and black, which makes the assembly or adjustment of the next process difficult, and may even result in scrapping. The main reason for this problem is that the riveted parts are too long, the force is not too short when the riveting is too short, the assembly deviation is wrong or the design size is wrong, and the parts are improperly placed. When riveting, the operator should first check the size of the parts, the appearance, and whether the tool is accurate. If the tool is not installed, it will affect the assembly quality of the electromagnetic system or the deformation of the core and the thickness of the pier.

Fourth, glass insulator damage

The glass insulator is made of metal pins and glass sintered. It is easy to bend the pins during inspection, assembly, adjustment, transportation and cleaning. The glass insulators are dropped and cracked, resulting in leakage and insulation and pressure resistance. Rotation also causes the contact reed to shift, affecting the reliable continuity of the product. This requires the operator of the assembly to handle it lightly during the entire process of relay production. The components should be placed neatly in the transfer box. It is not allowed to pull or twist the lead when assembling or adjusting.

Five, coil failure

There are many types of coils for relays, both outsourced and outsourced. The coils should be placed in separate special parts in separate parts. If the collisions are connected, the wires will be broken when separated. When the electromagnetic system is riveted, the pressure adjustment of the hand press and the press should be moderate. If the pressure is too high, the coil will be broken or the coil bob will be cracked, deformed, and the winding will be broken. If the pressure is too small, the winding will be loose and the magnetic loss will increase. Multi-winding coils are typically made with different colored leads. When welding, you should pay attention to the resolution, otherwise it will cause the coil to be soldered. The coils with the requirements of the beginning end are generally marked with the method of marking to indicate the beginning. Care should be taken when assembling and welding, otherwise the relay level will be reversed.