Decrypting Signal Relays: How to Implement Signal Conversion and Control

In today's era, signal relays are key components of electronic/electrical systems in the United States and other international countries, and electrification is further advancing every day around the world, including in the United States. They are not only used for conversion, but also capable of controlling and switching signals between various other devices. This can help engineers and technicians better understand the working principles and applications of the equipment, thereby improving its reliability and performance.

Signal relay is just an electrical switch device used to process low voltage signals ranging from 2 V to several hundred volts, such as enhanced or attenuated connections. It has the function of controlling when to turn on the output based on changes in the input signal. Signal relay: Unlike power relay, signal relay is used to switch low voltage or low current signals. We use them for industrial automation, communication systems, testing facilities, and other services.

Some of the main uses of signal relays are:

Convert to signal: Convert the received electrical signal into a more informative form, which will change the operation of subsequent circuits.

Isolation signal: prevent direct conflict between high voltage signals and low voltage control systems.

Signal amplification: Relay control circuits can amplify signals to drive high load current applications.

The working principle of a signal relay is similar to other types of relays, and its core components include coils, contacts, and external circuits. The following is the basic workflow of a signal relay:

Coil electrification: When current passes through the coil of a relay, the coil generates a magnetic field. This magnetic field will attract or repel the contacts of the relay.

Contact switching: The magnetic field generated by the coil can cause changes in the contacts of the relay. When the input signal reaches the rated condition, the contact will switch from the normally open (NO) position to the normally closed (NC) position, or vice versa.

Signal control: The contacts of relays can be used to control devices in other circuits. When the contacts of a relay change, it can activate, deactivate, or switch signal transmission in external circuits, thereby affecting the working state of the equipment.

Signal relays are commonly used to handle low voltage control signals, such as 0-24V DC or AC voltage (such as 12V AC). When the input signal changes, the contacts inside the relay will turn on or off, thereby achieving signal conversion or control.

3D diagram of signal relay

Signal relays convert low voltage and/or current signals on these lines into higher currents, thus enabling them to work together with the contacts of control relays. For example, you can use a 5V input signal to switch the contacts of a relay and control devices with higher voltage (12 Ie 220).

This conversion method is generally used for high-power loads and signal relays, so the current carrying capacity should not be too large and cannot directly carry high-power currents. Instead, the switch operation of the contacts is used to switch between different circuits.

Signal relays are also used for signal conversion, converting direct current (DC) to alternating current (AC) in both directions. Usually achieved through the use of different relay contact configurations. Relays can connect AC loads to DC power sources or connect DC signals to circuits.

In some automation equipment, it may be necessary to use relays to convert signals from different voltage systems to each other.

Sometimes signal relays are also used to convert a certain state logic (such as high, low) into other outputs within the control system. For example, sensors may output a 0V signal level, and relays can convert it to a high-level signal level to turn on other devices such as actuators or alarms.

Some signal relays can achieve signal reversal during operation (such as converting high levels to low levels, and vice versa). This is usually accomplished by using specific circuits or contact configurations in the relay.

When the input signal is too weak, the signal relay can amplify the signal by connecting an appropriate driving circuit, thereby converting weak signals (such as sensor signals) into strong signals, driving larger loads or linking with other devices.

For example, in remote control systems, weak sensor signals can be amplified by relays and used to drive distant devices.

William Relay Engineer specializing in writing blog articles on automation equipment electronic components and relay industrial control equipment