Power
Relays evolve to address the smart building challenge
By Iker Saenz, European strategic marketing manager – automation, Omron Electronic Components Europe B.V.
T
he homes in which we live and the offices where we work are undergoing many changes, both in response to the pandemic and to the ever-present need to address our environmental footprint by reducing wasted energy. As a result, we are all getting used to living and working in smart homes and smart offices, and are seeking to add new features to them such as micro-energy generation and EV chargers.
Open the case of almost all these systems and you’ll find electromechanical PCB relays used at the output. They are popular because they are reliable, safe, provide high isolation and are cost-effective. Relay manufacturers such as Omron have risen to the opportunity presented by building automation and evolved new solutions to address the challenges presented by these applications.
Relays for building automation systems
In typical building automation systems, the loads vary enormously and include heating, air conditioning, lighting and other elements. The latest technologies being applied place new demands on relays. Manufacturers like Omron have developed a platform relay series that address all the different requirements of a building automation system. For example, its G5Q family offers different specifications with the same PCB connection to meet different switching needs.
In common with other classes of components, relay manufacturers are being challenged to make their components more compact. Designs that are almost 30 mm long used to be perfectly acceptable – not anymore. The G5Q therefore is only 20 mm long by 15 mm high by 10.3 mm deep but offers a high specification.
Specific applications have their own challenges. For example, LED lighting, water pumps and capacitive input filters with Power Factor Correction produce high inrush currents lasting normally for microseconds. This puts extreme loads on relay contacts. If
38 February 2022 The innovative contact used in the G5Q quadruples service life
relay contacts weld together this destroys the relay and thus the device. Type G5Q-1A-EL2 was developed for capacitive inrush currents in the µs range. Such relays can switch inrush currents of 40 A/100 µs and nominal cut-off currents of 1 A/250 V AC up to 100,000 times. This has been achieved due to a new contact shape, which suppresses contact bounce therefore reducing arcing and increasing service life.
The same design is available for inductive motor loads (e.g., fans) which have longer lasting inrush currents in the millisecond range. The G5Q-1A-EL3 is designed accordingly and can perform approximately 300,000 operations with 250 V AC/30 A 500 ms inrush currents (inductive load) with a 3A cut-off current.
PWM controlled and latching relays Relays themselves use power to operate and reducing this is also a concern for system designers. The main source of this is the ‘coil holding current’ needed to keep the relay contact closed when the circuit is energised.
Components in Electronics
Omron Electronic Components Europe has launched relays supporting pulse width modulation (PWM) of the holding current, reducing the duty cycle and hence the average current. Omron G2RL, G5Q and G5NB relays are now available in this form, offering coil power levels 75-90 per cent lower than comparable standard versions. This decreases the power consumption and hence the heat developed in the relay, improving efficiency and reducing thermal load especially in applications where banks of relays are employed. All three families are optionally available in IEC/EN 60335-1 conformant versions.
Latching relays eliminate the need for a coil holding current altogether. For example, Omron’s new 16A G5RL-K-EL latching type relay is approved to IEC60669-1 and has a high inrush current capability up to 255A, making it ideal for demanding switching environments where loads vary enormously. The device is also compatible with the International Safety Standard for Electrical/ Electronic Household Appliances (IEC60335-1).
Solar panels and EV charging points Newer features of our homes and offices such as energy storage systems (ESS) for solar panels or vehicle to home (V2H) charging points for electric vehicles (EVs) have their own specific switching requirements. Omron Electronic Components Europe has launched a small footprint DC power relay for these applications that frees up PCB space without compromising performance. A single G5PZ-X relay, at just W15.2 x L26.4mm, covers 200VDC/20A, but two relays can be connected in series to switch currents at 400VDC/20A.
Conclusion
Our homes and office environments are changing rapidly, but the new systems that we are using demand new types of relays, especially DC power relays to control them. Relay manufacturers such as Omron are rising to the challenge of supplying new designs of components to address the requirements imposed by a sustainable, energy efficient world.
https://omron.co.uk www.cieonline.co.uk
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