What is an intermediate relay Intermediate relay selection elements

What is an intermediate relay?

It can be used in electromechanical protection and automatic control system to increase the number and capacity of contacts, not only the intermediate relay can also be applied to the circuit to provide the function of transmitting intermediate signals. It's basically similar to an AC contactor, both in terms of structure and in terms of how it works. However, there are some differences, among which the most important difference is that the main contact of the contactor can pass a large current, while the contact of the intermediate relay can only pass a small current, so it can only be applied to the control circuit. Moreover, it usually has no main contact, because the overload capacity is relatively small, so the intermediate relay USES all auxiliary contacts and a relatively large number of them.

Intermediate relay selection elements

Generally speaking, these aspects need to be taken into account when selecting this kind of relay, among which there are mechanical functions, installation environment, input of excitation coil, contact output and other elements. Next, we will focus on these elements of selection of intermediate relay.

1, mechanical action: here need to take into account the main vibration, impact, collision, such as stress principle and the function, for use in control system for installation in the middle of the relay, the selection of special even when considering the earthquake resistance, resistance to mechanical stress such as the ability of appropriate selection using balanced armature mechanism of miniature intermediate relay.

2, installation environment: the need to consider here are all installation altitude, temperature, humidity, and selection of elements such as electromagnetic interference, and usually consider the universal applicability of control system, both must be after the particularity of reliable operation, then in the key parts of the relay must choose to use with high insulation, strong resistance performance of whole sealing type, whether metal cap seal or encapsulation type, but better than metal encapsulation of intermediate relay. Only a fully sealed relay can have good long-term endurance to harsh conditions, as well as electrical contact stability and reliability, and the ability to switch loads (independent of external climatic conditions).

3. Input parameters of excitation coil: including excitation, front excitation, low-voltage excitation and high-voltage (220V) output isolation, as well as the influence of temperature change, long-distance wired excitation, electromagnetic interference excitation and other important factors. In fact, these are all factors to ensure the reliability of the automation equipment of the power system in the future operation process. Excitation according to the excitation quantity stipulated by the intermediate relay is a necessary condition to ensure its reliable and stable operation.

4. Contact output (switching) parameters: capacitive load, motor load, resistive load, contactor (relay) coil load and inductor, etc. Contact load value (open circuit voltage value, closed circuit current value), and includes low level load, dry circuit load, small current load, large current load and other factors. Therefore, any automation equipment needs to choose appropriate and matching load nature and auxiliary value size according to the actual requirements, and the correctness of the selection of intermediate relay is also particularly important.

What is the above intermediate relay? Intermediate relay selection elements, I hope to help you.