The SSR-CU Solid State Relay Control Unit from Electronic Design Service (EDS) provides safe and reliable switching of AC-powered devices using a low-voltage control signal.
The unit integrates a high-power solid-state relay and provides full galvanic isolation between the low-voltage control electronics and the AC power circuit. This allows microcontrollers, single-board computers, or automation systems to safely control electrical loads such as pumps, heaters, lights, or other AC equipment.
The SSR-CU enables modern automation systems to control standard electrical outlets without exposing sensitive electronics to dangerous high voltages.
The SSR-CU solid state relay control unit enables safe switching of AC loads using low-voltage control signals from microcontrollers or automation systems.
Key Features
• High-power solid-state relay switching for AC loads
• Full galvanic isolation between control and power circuits
• Compatible with 3 – 32 VDC control signals
• Designed for 24 – 280 Vrms AC loads
• Two output sockets:
Always-On outlet
Controlled outlet
• LED indicators for power and relay status
• Compatible with microcontrollers and automation systems
Typical Applications
The SSR-CU is designed for safe electrical load control in automation and monitoring systems.
Typical applications include:
• sump pump control systems
• home automation platforms
• IoT monitoring devices
• microcontroller-based control systems
• remote switching of AC loads
• integration with smart monitoring devices
The SSR-CU can be used together with the SPM-010 Smart Sump Pump Monitoring System to automatically control pump operation based on monitoring conditions.
How the SSR-CU Works
The SSR-CU receives a low-voltage control signal (3–32 VDC) from a microcontroller, automation system, or other electronic device.
This control signal activates the internal solid-state relay, which switches the AC power delivered to the controlled outlet.
Because the relay is optically isolated, the control electronics remain electrically separated from the high-voltage AC circuit.
This architecture provides:
• improved electrical safety
• protection for control electronics
• reliable switching without mechanical contacts
Available Versions
Two SSR-CU versions are available:
SSR-CU_12A
Maximum load current: 12 A
SSR-CU_6A
Maximum load current: 6 A
Both versions use the UPD2425 zero-voltage switching solid-state relay, rated for up to 25 A internal switching capacity.
Operating Environment
Operating Temperature: 32 °F – 90 °F (0 °C – 32 °C)
Operating Humidity: 0 – 85 % non-condensing
Integration with EDS Devices
Engineering Design
Like all EDS devices, the SSR-CU is designed using engineering principles commonly applied in avionics electronics development. This approach ensures reliable operation, electrical safety, and long-term durability in real-world installations.
Electrical Specifications
Output
Operating Voltage: 24 – 280 Vrms
Maximum Load Current:
- 12 A (SSR-CU)
- 6 A (SSR-CU_6A)
Transient Overvoltage: 600 V peak
Maximum Surge Current: 239 A peak
Maximum On-State Voltage Drop: 1.4 Vrms
Operating Frequency: 47 – 440 Hz
Control Input
Control Voltage: 3 – 32 VDC
Minimum Turn-On Voltage: 3 VDC
Minimum Turn-Off Voltage: 1 VDC
Maximum Input Current: 10 mA
Minimum Turn-On Current: 3 mA
Learn More or Contact Us
For additional information about the SSR-CU or other EDS monitoring and control devices, please visit our Contact page.