SSR-LA Linear Control Solid State Relay
4-20mA Input with Zero-Cross Technology for Precision Industrial Control
Product Overview
The SSR-LA series is a precision linear control solid state relay designed for industrial automation systems requiring 4-20mA input signals. Utilizing advanced semiconductor technology and zero-cross detection, it provides reliable switching without mechanical contacts, ensuring long service life and silent operation. With input current range of 4-20mA and load voltage capability of 24-480V AC, it offers exceptional compatibility with various process control systems and industrial applications. The zero-cross feature minimizes electromagnetic interference and inrush current, making it ideal for resistive and inductive loads in process control environments.
Key Advantages
4-20mA Input
Industry-standard 4-20mA current loop input for process control applications.
Zero-Cross Triggering
Minimizes EMI and inrush current with precise zero-cross detection technology.
Fast Switching
Operate and release time of ≤0.5 cycles +1ms for responsive control.
Wide Voltage Range
Input: 4-20mA, Load: 24-480V AC for versatile applications.
High Current Capacity
Available in multiple models from 10A to 125A load current ratings.
High Isolation
Excellent dielectric strength of 2500VAC and insulation resistance ≥100MΩ.
Wide Temperature Range
Operates reliably in ambient temperatures from -30°C to 80°C.
Low Leakage Current
Maximum leakage current of 10mA ensures energy efficiency and safety.
Current Range Options
Industrial Application Scenarios
The SSR-LA series solid state relays are ideal for process control applications where 4-20mA signals are standard. Their zero-cross operation and linear control capabilities make them particularly suitable for precise control of resistive and inductive loads with minimal EMI in industrial environments.
Process Control Systems
Precise control of industrial processes using standard 4-20mA control signals from PLCs and controllers.
Key Benefits:
- Direct compatibility with process control instrumentation
- Noise immunity of current loop signaling
- Long-distance signal transmission capability
Temperature Control Systems
Precise control of heating elements in industrial ovens, packaging machines, and plastic processing equipment with PID controllers.
Key Benefits:
- Accurate proportional control
- Zero-cross switching prevents current surges
- No acoustic noise during operation
Flow and Pressure Control
Control of pumps, valves, and actuators in fluid handling systems based on 4-20mA sensor inputs.
Key Benefits:
- Linear response to control signals
- High reliability for continuous operation
- Reduced EMI for sensitive control systems
Motor Speed Control
Control of small motors, fans, and blowers in automation systems using 4-20mA speed references.
Key Benefits:
- Smooth speed control
- No contact bounce for precise control
- High resistance to shock and vibration
Test & Measurement Equipment
Precise control in laboratory equipment, environmental chambers, and measurement devices with analog control inputs.
Key Benefits:
- Minimal EMI prevents interference with sensitive measurements
- High accuracy and repeatability
- Compact size for space-constrained applications
Lighting Control Systems
Industrial and commercial lighting control using 4-20mA dimming signals for energy management systems.
Key Benefits:
- Smooth dimming control
- Extended lamp life with soft switching
- No audible switching noise
Wiring Diagram
Connection Guide:
Proper wiring for 4-20mA input control and AC load connections. Ensure correct polarity for current input and appropriate heatsinking based on load current.
Heatsink Recommendations
Thermal Management:
Proper heatsinking is essential for optimal performance. The required heatsink size depends on load current, ambient temperature, and duty cycle. Consult our technical datasheet for detailed thermal guidelines.
Technical Specifications
| Parameter | Specification |
|---|---|
| Input Current Range | 4-20mA |
| Load Voltage Range | 24-480V AC |
| Load Current Range | 10A, 25A, 40A, 60A, 80A, 100A, 125A |
| Control Method | Zero Cross |
| Operate Time | ≤0.5 cycles of load power +1ms |
| Release Time | ≤0.5 cycles of load power +1ms |
| Leakage Current | 10 mA max |
| Dielectric Strength | 2500 VAC 50/60Hz for 1min |
| Insulation Resistance | ≥100MΩ |
| Ambient Temperature | -30~80℃ |
| Ambient Humidity | 45-85%RH |
| Terminal Fixed Torque | 1.6-2.2N.m |
| Mounting Method | DIN rail or screw mounting |
| Housing Material | Flame-retardant PBT |
| Weight (approx.) | 45g (10A) to 190g (125A) |
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