Description
The Yangming FOTEK SSR-40DA is a single-phase solid-state relay (SSR) designed for high-reliability switching of AC loads using a low-voltage DC control signal. Unlike electromechanical relays, the SSR uses semiconductor (thyristor) output with zero-cross switching, eliminating contact wear, arcing, and electrical noise during switching . This makes it suitable for frequent switching applications, temperature control systems, and environments where reliability and silent operation are important.
The relay accepts a DC control voltage of 4–32V (some sources list 3–32V) and switches AC loads from 24V to 380V AC, with a nominal current rating of 40A max . Key protection features include overheat protection circuitry, high surge current tolerance (over 10× rated current for one cycle), and double surge absorption circuits . The input and output circuits are optically isolated with dielectric strength exceeding 4KV, ensuring safe separation between control electronics and mains voltage .
Critical limitations: Solid-state relays generate heat during operation—a heatsink is mandatory for loads above 5A, and forced air cooling is recommended for sustained currents near the rated limit . Without adequate thermal management, the relay will overheat and fail. The 40A rating is a maximum, not a continuous operating recommendation; derating is required based on load type and ambient conditions . The relay is not suitable for precise speed control of asynchronous motors .
Features
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Zero-Cross Switching: Turns on/off at AC voltage zero-crossing, minimizing electrical noise and inrush current .
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Optical Isolation: Input and output circuits are isolated with dielectric strength >4KV for safe control of mains loads .
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High Surge Tolerance: Withstands surge currents over 10× rated current for one cycle .
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Overheat Protection: Built-in thermal protection circuit prevents damage from overheating .
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Wide Control Voltage (4–32V DC): Compatible with Arduino, PLCs, and industrial control systems .
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Wide Load Voltage (24–380V AC): Suitable for most single-phase AC applications .
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Silent Operation: No mechanical contacts, eliminating audible noise and wear .
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LED Status Indicator: Visual confirmation of relay activation .
Technical Specifications
| Parameter | Specification (FOTEK SSR-40DA) |
|---|---|
| Control Voltage | 4–32V DC (some sources list 3–32V) |
| Load Voltage | 24–380V AC |
| Rated Current | 40A max |
| Control Method | Zero-cross trigger (DC to AC) |
| Dielectric Strength | >4KV |
| Isolation Resistance | >100MΩ / 500VDC |
| Surge Current | >10× rated current (1 cycle) |
| Response Time | ≤10ms |
| Operating Temperature | -20°C to +80°C (varies by source) |
| Mounting | Panel mount (screw terminals) |
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