Solid State Relay (SSR): Low‑Noise Switching Solutions

Solid state relay, also known as SSR, offers high-performance, low-maintenance alternatives to mechanical relays, ensuring smooth operation and noise-free switching in industrial and commercial applications. United Automation’s SSR range, including the LN Series (single-phase) and LN3P100 Series (three-phase), delivers reliable control, UL-listed safety, and industry-leading efficiency.

What Are Solid State Relays (SSR)?

A solid state relay (SSR) is an electronic switch that uses semiconductor components (such as thyristors or triacs) to control power to a load without mechanical contacts. Unlike electromechanical relays, SSRs offer:

• Noise-free operation (no clicking)
• Fast switching speeds
• High reliability with no moving parts
• Extended lifespan in demanding environments

United Automation’s SSRs are designed to handle both single-phase loads (LN Series) and three-phase systems (LN3P100), making them ideal for a wide range of industrial control tasks.

Product Specifications

✅ LN Series – Solid State Relay (Single‑Phase, Low-Noise SSR)

• UL Listed: UL‑US‑2013894‑0, UL‑CA‑2011013‑0
• Rated Voltage: up to 280 VAC
• Current Options: typically 10 A to 50 A
• Zero-cross switching for minimal electrical noise
• Compact DIN‑rail or panel mounting
• Designed for resistive or inductive loads

✅ LN3P100 Series – Solid State Relay (Three‑Phase)

• Three-phase support for large loads up to 100 A
• Industry-grade rugged housing for panel installation
• Synchronous switching across all phases
• Ideal for three-phase heaters, motors, or industrial ovens

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SSR-50A-530V | LN3P10050 Solid State Relay

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SSR-15A-530V | LN3P10015 Solid State Relay

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SSR-75A-240V | LN Series Solid State Relay

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SSR-50A-240V | LN Series Solid State Relay

Applications of Solid State Relay (SSR)

⚡ Industrial Heating & Temperature Control

• SSRs drive resistive elements like infrared heaters, ovens, and heat lamps
• Zero-cross switching minimises electrical interference and ensures precise temperature control

🏭 AC Motor & Fan Control

• Ideal for variable fan speed systems, conveyors, and pumps
• Low-noise SSRs contribute to quieter and cleaner control rooms

🧪 Laboratory & Medical Equipment

• Precise and silent switching protects sensitive environments
• UL-certified models provide safety and regulatory compliance

🏨 Commercial Catering & Hospitality

• Used in quartz-lamp controllers and catering heater systems
• Reliability and long service life reduce maintenance interruptions

How SSRs Improve Industrial Control

Noise Reduction & Reliability

SSRs eliminate mechanical wear and eliminate audible “clicks,” providing low noise SSR operation and high reliability even in continuous-duty cycles.

Faster Switching & Longer Life

Without moving parts, SSRs offer rapid switching and extended service life—ideal for heating cycles and frequent on/off control.

Safety & Compliance

United Automation’s LN Series single-phase SSRs are UL Listed, ensuring compliance with North American standards. They guarantee safe integration into commercial and industrial systems.

Reduced Electromagnetic Interference

Zero-cross switching significantly reduces harmonic distortion and electromagnetic interference—an advantage in sensitive control panels and noisy environments.

Who Benefits from Solid State Relay (SSR)?

• OEMs and Panel Builders integrating reliable switching modules in industrial systems
• Plant Maintenance Engineers aiming for maintenance-free, long-life solutions
• Food Manufacturing & Catering Engineers using SSRs in infrared heating and food warming systems
• HVAC Technicians and Electrical Contractors working with fan and motor control applications
• Medical and Laboratory Facility Managers requiring accurate, silent, and safe power switching

Why Choose United Automation SSRs?

• British engineered quality with decades of power control expertise
• UL Listed (LN Series) for global regulatory compliance
• Low-noise design — perfect for environments sensitive to electric or acoustic interference
• Robust circuitry for industrial-grade reliability and minimal maintenance
• Flexible models catering to single-phase through three-phase control needs

Check the full SSR portfolio here:
🔗 United Automation SSR Products

Investing in solid state relay (SSR) technology ensures smoother, quieter, and more reliable switching in challenging industrial environments. With United Automation’s UL Listed SSR products, you get precision, compliance, and peace of mind.

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🔗 Explore the full SSR range