Solid State Relays: How to Choose the Right Type

In modern industrial automation, choosing the right type of relay is critical to ensure system efficiency, reliability, and longevity. One increasingly popular option is the Solid State Relay (SSR) — a fast, silent, and durable alternative to traditional electromagnetic relays.

At Beijing Strong Electric, we provide a wide range of SSRs tailored for various industrial applications, including heating, motor control, lighting, and more. This guide will help you understand the different types of SSRs and how to choose the one that fits your needs.

What is a Solid State Relay (SSR)?

An SSR is an electronic switching device that uses semiconductor components — like thyristors, triacs, or transistors — instead of mechanical contacts. The result? A relay that’s faster, quieter, and longer-lasting.

Common Types of SSRs and Their Applications

1. DC-to-AC SSRs (e.g., SSR-40DA)

• Input: DC control signal (e.g., 3–32VDC)
  
• Output: AC load switching (e.g., 24–380VAC)
  
• Typical Use: Heating elements, ovens, motors
  
• Strong Electric Model: SSR-DA-Series-Single-Phase-SSR
  

2. AC-to-AC SSRs

• Input: AC control signal
  
• Output: AC load
  
• Use Case: Ideal for synchronizing AC control systems
  
• Available on request
  

3. DC-to-DC SSRs

• Input: DC control
  
• Output: DC load (e.g., motors, LED lighting)
  
• Best For: Low-voltage DC circuits
  
• Available on request
  

How to Choose the Right SSR

When selecting a solid state relay, consider the following:

• Control Voltage: Make sure the input signal from your PLC, sensor, or control board matches the SSR's input range (e.g., 3–32VDC).
  
• Load Voltage & Current: Choose a relay with a voltage and current rating that exceeds your maximum load (e.g., 40A @ 380VAC).
  
• Heat Dissipation: SSRs generate heat. Pair with a heat sink for loads over 10A.
  
• Switching Type: Zero-crossing (for resistive loads) or random turn-on (for inductive loads or phase control).
  

Why Choose Strong Electric SSRs?

✅ High Performance Components
We use premium-grade semiconductors for stable, reliable switching — even under heavy load.

✅ Wide Product Range
From 10A to 120A, we have models that meet the needs of light-duty applications and industrial power control alike.

✅ Compact, Safe Design
Each relay is compact, DIN-rail or panel mountable, with optical isolation between input and output for safety.

✅ Fast Shipping & Technical Support
We offer global delivery and responsive support to help you select the right products for your application.

Featured Product: SSR-25DA

• Input: 3-32V DC
  
• Output: 24-380V AC
  
• Load Current: 25A
  
• Compact size and durable housing
  
• View full product details »
  

At Strong Electric, our goal is to help you build safer, smarter, and more efficient systems — one component at a time. Explore our full range of SSRs and automation products at www.strong-ele.com.

Need help choosing? Contact us today. We're here to assist!