Special issues to be aware of when using relays

What are the special problems and analysis that should be paid attention to when using relays during the use of relays?

1. About sealed relays and unsealed relays:

Some engineers and technicians believe that the non-sealed products are intuitive in operation and convenient in failure analysis, while the operation process of the fully sealed products is invisible. It is subjectively determined that non-sealed products are more reliable than fully sealed products. This concept of intuitive recognition is very wrong. .

The advantage of the non-sealed relay is that it adopts the snap-on armature, the structure is simple, the manufacturing process is simple, the installation and maintenance are convenient, the working state is intuitive, the failure analysis is convenient, and the price is cheap. The main disadvantage is that the reliability of work is sensitive to changes in the use environment (climate stress, mechanical stress). The long-term weather resistance performance is prone to environmental pollution and damage over time. The electrical contact stability and reliability are poor. Moisture and impurity contamination cause electrical corrosion, mildew and failure.

The advantage of the fully sealed relay is that it adopts the balance rotary armature, the full sealing mechanism isolates the external climatic stress, has excellent anti-corrosion performance, and the contact electrical contact performance is stable and reliable. The coil is resistant to corrosion and mildew, and the long-term reliability is excellent. The disadvantage is the structure. It is complicated, the manufacturing process is complicated, the failure analysis is difficult, it can not be reused after maintenance, and the cost is high.

Therefore, from the perspective of long-term weather resistance performance, harsh environmental performance and reliability of electrical contact stability, fully sealed relays are superior to non-sealed relays. Especially for products using relays in high-voltage switches, fully sealed relays should be used. Special requirements for automatic power control and long-term stability.

2. Parallel and series connection of relay contacts:

The use of relay contacts in parallel does not increase the load current, because the action of multiple sets of contacts of the relay is absolutely different at the same time, that is, the first set of contacts that are switched on first switches the increased load, and the other contacts in parallel No action, it is easy to make the contact damage without contact or fusion welding can not be disconnected, the contacts are connected in parallel.