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In the electronics industry, surge current protection is one of the most critical topics when designing reliable systems for power supplies, energy storage, EVs, industrial controls, and medical devices.
Yet, a common misconception persists:
“If there’s already a fuse, do I still need surge current protection?”

The answer is yes. A fuse and an NTC thermistor serve completely different roles—and both are essential for long-term product reliability.

What Is Inrush (Surge) Current?

When a device powers on, components like large capacitors, transformers, or motors draw a sudden, high-amplitude current spike.

This short-lived current can cause:

⚡ Damage to semiconductors, PCB traces, or connectors.

⚡ Nuisance fuse blowing, leading to unnecessary maintenance.

⚡ Long-term system instability and reduced product lifetime.

Fuse ≠ Surge Suppression

A fuse is designed to respond to severe faults or short circuits—but it does not actively suppress inrush current.
Without proper surge control, systems risk:

• Frequent fuse replacements, slowing production and raising costs.
• Component failure and higher field returns.
• Increased warranty and service expenses.

The Proven Solution: NTC Thermistor + Fuse

The industry standard approach combines active suppression with passive protection:

✅ NTC Thermistor: High resistance at startup limits inrush current effectively.

✅ Self-Adjusting Behavior: As it warms, resistance drops, minimizing power loss.

✅ Fuse Integration: Ensures fault isolation in case of catastrophic failure.

✅ Optional Relay Bypass: Enhances efficiency for high-power or frequent start-stop applications.

Global Best Practice

From energy storage systems to EV power trains, industrial automation, and medical electronics, leading manufacturers rely on this combined approach:

• NTC Thermistor → Active inrush suppression.
• Fuse → Fault and over-current protection.
• Relay Bypass (where needed) → Durability and efficiency boost.

This layered design philosophy has been validated across industries worldwide.

Why Engineers Choose Shiheng Electronics？

With over 20 years of expertise in NTC thermistors and inrush current limiting solutions, Shiheng Electronics supports global customers by providing:

✔ A complete NTC inrush limiter portfolio for mainstream and custom needs.

✔ Balanced solutions across reliability, cost, and design flexibility.

✔ Responsive technical support to help engineers shorten development cycles.

Better surge protection doesn’t just safeguard your product—it safeguards your reputation.

Looking for the right inrush protection solution for your next design? Contact Shiheng Electronics to get expert application support and tailored product recommendations.