Description
Product Overview
The 3V to 24V 1 Way Solid State Relay (AC Controlled DC) is a specialized semiconductor switching device designed to control DC loads using an AC control signal. Unlike conventional DC-input SSRs, this module accepts an AC voltage input (typically from a 24V AC transformer, thermostat, or HVAC controller) and switches a DC load on the output side .
This module is specifically engineered for applications where the control signal is AC, such as building automation systems, HVAC equipment, industrial controllers, and legacy systems that provide AC control outputs. The SSR features opto-isolated switching, providing complete electrical isolation between the AC control side and the DC load side for enhanced safety and noise immunity .
The module supports a wide AC control voltage range of 3V to 24V AC/DC (depending on the variant) and is available in both High Level Trigger and Low Level Trigger configurations . The output side is designed for DC loads, typically up to 3.5A at 24V DC or higher for some variants, making it suitable for controlling solenoids, valves, DC motors, LED lighting, and other DC-powered equipment.
Unlike mechanical relays, this SSR offers silent operation, faster switching speeds, no contact wear or arcing, and a significantly longer lifespan—ideal for applications requiring frequent switching or operation in hazardous environments where sparks must be avoided .
Key Features
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AC Control Input: Designed to accept AC control voltages from 3V to 24V AC/DC, making it compatible with HVAC controllers, thermostats, and industrial AC output modules .
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DC Load Switching: Output side switches DC loads up to 3.5A at 24V DC (or higher depending on variant), suitable for solenoids, valves, DC motors, and LED lighting .
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Selectable Trigger Mode: Available in both High Level Trigger (active HIGH) and Low Level Trigger (active LOW) versions to match your application needs .
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Optical Isolation: Provides galvanic isolation between the AC control side and the DC load side for enhanced safety and noise immunity. Isolation voltage typically rated at 2500V-4000V AC .
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Fast Switching Speed: Solid-state design enables rapid switching with typical turn-on times of ≤ 10ms, suitable for high-frequency control applications .
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Zero-Current Switching: Many AC-input models incorporate zero-crossing detection to minimize switching noise and inrush current .
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Built-in Snubber Circuit: Includes an internal RC snubber to protect against voltage spikes and reduce EMI when switching inductive DC loads .
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Status Indicator LED: Onboard LED provides clear visual confirmation of relay activation status .
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Compact Module Design: Small footprint with screw terminals for easy wiring and DIN rail or panel mounting options .
Technical Specifications
| Parameter | Operating Value |
|---|---|
| Control Voltage (AC/DC) | 3V – 24V AC/DC |
| Control Current | 5mA – 15mA (typical) |
| Control Signal (High Level) | 3V – 24V AC/DC |
| Control Signal (Low Level) | 0V – 1.5V AC/DC |
| Load Voltage (DC) | 5V – 48V DC (varies by model) |
| Load Current (Max) | 3.5A (typical) – up to 40A for high-power models |
| Output Type | MOSFET or IGBT (DC switching) |
| Output ON Resistance | ≤ 0.1Ω (typical) |
| Operate Time (Turn-On) | ≤ 10ms |
| Release Time (Turn-Off) | ≤ 10ms |
| Isolation Method | Optocoupler (optical isolation) |
| Isolation Voltage | 2500V – 4000V AC (input to output) |
| Operating Temperature | -30°C to +80°C |
| Dimensions | Varies by module (typically 25-50mm × 20-35mm) |
| Weight | Approx. 13g – 30g |
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