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A Significant Role of Communication Systems: Signal Relay

A Significant Role of Communication Systems: Signal Relay

March 04 , 2024 0

Relays, an electronic device with a history dating back to 1835, remain a widely utilized and valuable component in various industries. Despite their age, they continue to play a significant role, enabling remote control of circuits from a distance and finding applications in diverse fields. In the early days of computing, relays were instrumental, forming the basis of Boolean logic functions in numerous computer systems. Among the diverse types of relays, signal relays stand out as a crucial subcategory, serving specific purposes and holding a significant role in communication systems. This article aims to introduce signal relays, covering their definition, distinctions from other relay types, essential selection criteria, and more.

What is Signal Relays?

Signal relays are primarily employed for load switching below 2A and find application in various fields, including telecom and network devices, test and measurement equipment, as well as security devices.

Small signal relays serve as electrically operated electromechanical switches designed to regulate the current flow in a circuit. They utilize a magnetic force generated by a control current passing through a coil near the contacts to manipulate internal components, moving contacts between open and closed positions. This mechanism enables a small signal to command a larger one. Unlike power relays, signal relays are tailored to handle low voltage and current, generally below 2 amps, and switch low power signals with voltage ratings typically ranging from 5 VDC to 30 VDC. They are commonly referred to as "low signal relays."

Primarily intended for low voltage and current applications, signal relays are optimal for scenarios requiring contacts specifically crafted for low power. While power relays, capable of handling higher current and voltage, may be more cost effective in certain applications, they can distort low power signals in audio or video circuits. Signal relays, with their compact packages suitable for board mounting, provide faster switching times. Additionally, they are usually more budget friendly than solid state relays and are not susceptible to voltage or current transients, or vulnerable to EMI/RFI. Due to their modest power handling, they generate less heat than solid state relays, typically eliminating the need for thermal management solutions in the circuit.

Signal Relay Features

Signal relays excel in providing reliable contact performance, especially with a small signal load, thanks to their gold pasted contacts and bifurcated crossbar structure. Given their primary function of switching current, signal relays typically incorporate a c contact structure. These relays are well suited for reflow mounting and can accommodate multiple mounting options, particularly in reel packages.

Signal Relay Benefits

Signal relays, similar to other electromechanical relays, provide numerous advantages in projects, including:

Simplicity in design

Electrical isolation

Robust operation

Cost savings in long distance wiring

Multiple packaging and feature options

Immunity to EMI/RFI

When appropriately tailored to the circuit's power needs, signal relays offer additional benefits such as:

Ease of operation

Compact size

Affordable cost

Resistance to mechanical shock

High insulation between the internal coil and contacts

Key Specifications And Selection of Signal Relays

When choosing a signal relay model for a design, various factors should be taken into account, including:

Voltage Rating: The maximum voltage the relay can switch, typically measured in VDC or VAC.

Current Rating: The maximum current the relay can switch, measured in Amps.

Contact Resistance: The resistance, measured in Ohms, added to the load circuit.

Coil Voltage: The rated control voltage for the relay coil.

Coil Current: The rated current that the coil takes with the rated coil voltage.

Contact Form: The relay’s switch configuration (number of poles and normally open or normally closed configuration), such as SPDT (1 Form C) and DPDT (2 Form C).

Contact Rating: The current and voltage values for guaranteed relay performance, typically expressed as 1 A @ 30 VDC.

Switching Time: The operating speed of the relay from when control current is applied to when the contacts close or vice versa.

Mounting Type: The mounting method of the application, either through hole or surface mount on the PC board.

Dielectric Strength: The maximum voltage a relay can tolerate without damage for a specified period.

Operating Temperature: The specified range of temperatures a relay can safely and successfully operate in without degradation.

With the above considerations, engineers can begin selecting a suitable signal relay for a project. Begin by determining the required voltage and current ratings based on the maximum switching load of the circuit. Signal relays typically handle loads of 2 A or less.

Identify the required control voltage and type, either AC or DC, and specify the number of poles/circuits to be switched. Determine whether the circuit requires a normally open (NO) or normally closed (NC) switching arrangement.

Lastly, consider the method of mounting the device in the circuit, such as panel mount, DIN rail, surface mount, or through hole. By identifying these specific parameters, engineers can choose a relay that meets the system's needs without over specifying.

Signal Relay Applications

Signal relays, with their capability for low power switching, find applications in a diverse range of settings, both consumer and commercial. They offer an efficient solution for network devices that necessitate long distance signals with voltage and current levels higher than what most electronics can handle inherently. In applications demanding quick responsiveness but not as much power as a power relay, signal relays prove to be valuable. In everyday scenarios, such as in homes and offices, where a thermostat operates at low voltage and current, a signal relay becomes instrumental. It can take the small, low power control signal and effectively transmit the message to the furnace or air conditioning (AC) unit, enabling them to take the necessary action.

In the evolving landscape of electronic systems, where increased sophistication demands comprehensive electrical isolation between a switching signal and the signal being switched, the role of signal relays becomes crucial. Signal relays serve as a solution for effectively controlling current and voltage remotely.

These devices find extensive applications across a spectrum of consumer and industrial products and systems, serving the purpose of power switching in various circuit configurations. CUI Devices, recognizing the diverse needs of design engineers, provides a comprehensive range of signal relays catering to the demands of low level current switching.

KUKE will continue to strive to meet customer needs as electronic components that can contribute to new generation power supplies, such as high quality general purpose relay. If you have any question about wireless / RF signal relay, please contact KUKE immediately.