The SSR-40DA Solid State Relay is a single-phase electronic switching device designed to control high-current AC electrical loads using a low-voltage DC control signal.
Featuring a 40A rated load current, 3–32V DC control input, and 24–380V AC output, this relay provides fast, silent switching without mechanical contacts.
It is suitable for industrial automation, heating systems, lighting control, and microcontroller-based automation projects.
Key Features
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40A Rated Load Current: Designed for switching compatible AC loads.
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DC-to-AC Operation: Controls AC loads using a low-voltage DC signal.
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3–32V DC Control Input: Compatible with suitable electronic control circuits.
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24–380V AC Load Output: Supports a wide range of AC applications.
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Zero-Cross Switching: Helps reduce switching interference for compatible AC loads.
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Silent Operation: No mechanical clicking or moving contacts.
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Solid-State Design: Eliminates mechanical contact wear.
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Screw Terminals: Convenient electrical connections.
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Protective Terminal Cover: Helps protect against accidental terminal contact.
Technical Specifications
| Parameter |
Specification |
| Model |
SSR-40DA |
| Product Type |
DC-to-AC Solid State Relay |
| Rated Load Current |
40A |
| Control Input Voltage |
3–32V DC |
| Load Output Voltage |
24–380V AC |
| Trigger Current |
Approx. 7.5mA at 12V DC |
| Switching Method |
Zero-Cross Trigger |
| Phase |
Single Phase |
| Control Type |
DC Input / AC Output |
| Connection Type |
Screw Terminals |
| Mounting Type |
Panel Mount |
| Cooling |
External Heatsink Recommended |
Terminal Configuration
| Terminal |
Function |
| 1 |
AC Load Terminal |
| 2 |
AC Load Terminal |
| 3 (+) |
DC Control Positive |
| 4 (−) |
DC Control Negative |
Note: Follow the terminal markings printed on the relay housing.
Microcontroller Compatibility
The SSR-40DA can be controlled using a suitable interface with:
- Arduino UNO and Mega
- ESP32 Development Boards
- ESP8266 Modules
- Raspberry Pi GPIO
- PLC Controllers with DC Outputs
Important: Direct GPIO control depends on the controller's output voltage and available current. A transistor driver or suitable interface may be required, especially for 3.3V controllers.
Applications
- Industrial Automation
- AC Heating Systems
- Temperature Controllers
- AC Lighting Control
- Electrical Control Panels
- Arduino and ESP32 Automation
- Raspberry Pi Projects
- Automated AC Load Switching
Important Notes
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AC Loads Only: The output is designed for AC loads and cannot switch DC loads.
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Heatsink Required: Use a properly sized heatsink and thermal compound for higher-current operation.
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40A Maximum Rating: Actual continuous current capacity depends on cooling, ambient temperature, and load characteristics.
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Inductive Loads: Motors and transformers may require additional derating and surge protection.
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Off-State Leakage: A small leakage current may remain when the relay is switched off.
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Electrical Safety: AC mains wiring must be installed by qualified personnel.
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Not a Circuit Breaker: Appropriate overcurrent protection must be installed separately.
Package Includes
