What is an intermediate relay?
The intermediate relay is an electronic element, also called a "circuit gain device", which is used to connect the circuits that are too far and enhance the transmission effect of current or voltage signals. The structure of the medium relays is relatively simple, and it is usually made up of a relay body, power supply, signal input terminal, signal output terminal, and so on.
The four major functions of intermediate relays
1, Increase the number of control circuits
If the device control circuit needs more numbers of contacts for different control functions, and the main controlling equipment such as contactor and circuit breaker and so on cannot meet the number requirement for contacts, then intermediate relays can be used to expand the number of control circuits. In complicated automation control systems, for instance, there are different control operations to be performed on various devices; here, due to control requirements, some extra contacts can be provided by the intermediate relays.
2, Signal amplification
When the control signal is weak, such as when the signal current output by some sensors is too small to directly drive high-power loads (such as contactor coils), the signal can be amplified through an intermediate relay. The coil of the intermediate relay requires a smaller control current, while its contacts can withstand larger currents and voltages, thereby achieving signal amplification and conversion.
When transmitting signals over long distances, the signal may attenuate. The use of intermediate relays can re amplify the signal at the signal receiving end, ensuring the reliability and accuracy of the signal.
3.Electrical isolation
It can also be used for electrical isolation in cases where voltage differences exist between two circuits, such as a high-voltage main circuit and low voltage. Segregation would help the control circuit avoid any form of damage because of the application of high voltage to it. It protects the operators' safety too.
When the control signal is from different power systems or has different grounding methods, the intermediate relay may avoid interference between different power systems and the influence of grounding circulation.
4, Change control mode
Various kinds of control signals can be converted. As an example, the DC control signal output by the transistor is changed into the AC control signal which is needed by the contactor, or the passive contact signal is transformed into an active signal.
In certain applications, the need arises to change some kind of control logic, and in such situations, the use of intermediate relays can assist in providing a way of control conversion by adopting different connection methods-such as converting positive logic control into negative logic control or switching between manual and automatic modes.
Under what circumstances is it necessary to add an intermediate relay?
- The circuit distance is too far
When the transmission distance of the circuit is too far, due to the existence of circuit resistance, the current or voltage of the transmitted signal will attenuate, resulting in a significant decrease in the efficiency of signal transmission. At this point, it is necessary to add intermediate relays to enhance the signal transmission effect.
- Weak transmission signal
In some cases, due to the small current or voltage of the signal transmission source, the signal transmission effect is poor. Adding an intermediate relay at this point can enhance the signal and achieve better transmission performance.
- Excessive circuit load
When the load of the circuit is relatively large, it is easy to cause the current or voltage of the emission source to fail to meet the requirements of the circuit, thereby affecting the normal operation of the circuit. At this point, adding an intermediate relay can enhance the current or voltage signal, meeting the requirements for normal circuit operation.
Summarize
Overall, adding intermediate relays can enhance the effectiveness of signal transmission in the circuit, improve the stability and reliability of the circuit. However, adding too many intermediate relays can also cause signal attenuation in the circuit, so it is necessary to add them according to the specific situation of the circuit in practice. Using high-performance intermediate relays can enhance the performance and lifespan of equipment. When purchasing intermediate relays, choose QIANJI to provide you with comprehensive services. Contact us now for discounts