Littelfuse built the new solid-state relay family to meet the rigorous reliability requirements of commercial and industrial machinery.Littelfuse has released the SRP1 solid-state relays (SSRs) family to meet customer demand for more reliable switching performance that reduces downtime in industrial and commercial machinery.
Traditional mechanical relays are often prone to failure when subject to prolonged use in challenging environments. The solid-state architecture of the SRP1 family addresses these limitations and is engineered for durability over extended periods of use in harsh environments.
According to Littelfuse, the key to the new relays' performance is a proprietary power component that is resistant to heat degradation and designed for high-frequency switching over extended periods of time. This results in fewer field failures and less costly equipment downtime.
The SRP1 SSRs are available in five configurations for easy installation and design flexibility across various applications, including industrial automation machinery, HVAC, and food and beverage equipment.
The Basics of the New Solid-State Relay's Operation
The SRP1 SSRs quickly block or pass AC line power to downstream equipment loads, such as cooking ovens, hot drink dispensers, traffic lighting control, HVAC equipment, plastic and packaging machinery, industrial ovens, and electronics production equipment.
At the heart of the SRP1 SSRs are power diodes and optical isolation circuitry (rated to 4000 Vrms) that consists of light-emitting diodes (LEDs) and photodetectors (PDs). The diode IP comes from the IXYS power semiconductor portfolio, including a range of rectifiers, fast-recovery diodes, and other diode types. The IXYS power circuitry within the SRP1 can support AC load currents up to 90 A at low or high voltages (up to 660 V, 50–60 Hz).
SRP1 functional block diagram.
The relay is controlled by either an AC or DC signal (depending on the model type) applied to its input terminals, which is passed across the optical isolation boundary to open or close the relay and control AC power to the output load.
The SRP1 series operates with either instantaneous (random turn-on) or zero cross-switching. For instantaneous switching, the relay turns on immediately regardless of the AC output cycle, while zero cross-switching coordinates the switching with the zero crossing of the AC load signal. The latter helps mitigate the generation of interfering signals from switching under load.
SRP1 switching properties.
According to Littelfuse, with no moving parts subject to wear and tear over repeated use, the SSRs offer two to three times more life endurance cycles than conventional relays. In many cases, solid-state relays can also open and close faster than their electromechanical counterparts.
Key Capabilities of the SRP1
Littelfuse engineered the new SRP1 relays to minimize operational disruptions due to equipment failure or maintenance, allowing customers to focus on efficient operations. Equipment uptime is critical to cost-efficient operations, making the SRP1's specified endurance the headline feature of the SSRs. Littelfuse designed the SRP1 series to support up to 750,000 life cycles, more than twice that of standard SSRs.
SRP1 lifecycles.
The SRP-1 series incorporates IP20 finger-safe protection and overvoltage protection to help with safe installation and is compliant with UL and IEC international standards governing safety and electromagnetic compatibility.
All images used courtesy of Littelfuse.
