Relay output parameters should be considered when selecting the following parameters: Contact Group Number Contact Form Contact load Contact material Electrical life, mechanical life
1, the load type Most of the domestic relay load capacity, only marked the largest pure resistive load, which gives users the choice of relay load, resulting in two kinds of misunderstanding, leading to selection mistakes. One of the misunderstandings is that it is often not a purely resistive load, but an inductive, lamp, motor or capacitive load that is practical for a user. The load size is equal or close to the resistive load. The second misunderstanding is that the load can be reduced from a low power Flat to rated load, can adapt. It should be noted that a relay capable of reliably converting a resistive load of 10 A can not convert an inductive load of 10 A, and certainly can not reliably convert a load of 10 mA. Because of the different nature of the load under the conditions of electrical contact failure mechanism is completely different. Automotive system uses DC power supply voltage, DC voltage zero crossings, instantaneous contact opening, that is, the arc, and because of the applied voltage continues to be maintained, only the arc is elongated, can not self-sustaining and extinguished. Arc heat can burn the contacts severely, and the DC current always flows in one direction, causing more contact material transfer. Most automotive relay load capacity, nominal resistive load only, but the actual use of automotive relays is often not a resistive load, but the inductive load, lamp load, motor load, due to the existence of high inrush current, steady-state load contacts The size should be based on the size of the impact of the use of derating. It should be emphasized that the contact failure is the main reason for the failure of the relay. Contact in different load types, different load conditions of the electrical contact characteristics, failure and failure mechanism is different.
2, contact material Contact material is the most critical material used by the relay, the level of its performance determines the quality level of the relay