What is “Thermal Runaway” in Industrial Electronics?

Think thermal runaway is “just a heat problem?” It’s actually a self-destruct sequence. And once it starts, it doesn’t stop until something fails. Heat builds. Resistance increases. Currents spike. The cycle feeds itself faster and faster — until components melt, blow, or burn out. It’s dramatic and very costly. And in many cases, it’s entirely preventable. So, what exactly causes thermal runaway, and how can you stop it before it gets out of control?

It starts with heat — and ends with more heat

Thermal runaway is a chain reaction. As a component heats up, its electrical resistance may change. This leads to more current flow and even more heat generation. The cycle repeats. Eventually, the component exceeds its thermal limits and fails entirely.

In industrial electronics, semiconductors are the usual suspects. MOSFETs, IGBTs, and diodes are particularly vulnerable when cooling is inadequate or when power supply fluctuations go unchecked. That’s why monitoring junction temperatures and verifying heat sink contact on power semiconductors is essential (especially in high-load applications).

Environmental factors can trigger the spiral

Even well-designed systems can fall victim to external conditions. Poor airflow, high ambient temperatures, and dirty filters can all set the stage for overheating. Poor ventilation doesn’t just raise internal temps — it entirely disrupts the system’s ability to stabilize itself. Keep a close eye on not just cooling systems, but also environmental factors that can impede those systems. Watch out for these red flags:

• Vents clogged with dust or debris.
• Cabinets installed too close to walls, limiting airflow.
• Cooling fans running slower than spec — or not at all.
• High humidity or corrosive air degrading heat sinks.

Power supply instability pours gas on the fire

Beyond cooling failures, voltage spikes and current surges force components to handle more than they’re designed for. Some components dissipate excess energy as heat, which increases their internal temperature and accelerates failure. The more erratic the supply, the harder it is for components to maintain thermal equilibrium. You might spot issues like:

• Intermittent brownouts that cause stress cycles.
• Fluctuating input voltage on older or overloaded circuits.
• Harmonics generated by nearby drives or motors interfering with power stability.

Aging components lose their ability to keep cool

As electronics age, their thermal efficiency drops. Thermal interface materials degrade. Capacitors dry out. Heat sinks lose contact. Fans seize up or slow down. None of it happens overnight, but together, they set the stage for runaway conditions. Remember — wear and tear are unavoidable, but it doesn’t have to be a death sentence if you catch the signs early:

• Heat sink compound that’s dry or cracked.
• Fan bearings that rattle or squeal.
• Increased thermal resistance between components and heat sinks.
• Circuit boards with darkened areas around heat-generating components.

Design flaws or misuse can accelerate failure

Not all failures are environmental or age-related. Sometimes the root cause is how the component is used — or misused. If thermal margins aren’t built in — or if equipment is used outside its design specs — thermal runaway is just waiting for the right conditions. There are some common scenarios that invite thermal stress:

• Underrated components pushed beyond their limits.
• Improper installation without thermal paste or sufficient spacing.
• Overclocked drives or processors generating excessive heat.
• Enclosures with no cooling provision at all.

The best defense is proactive inspection and cooling strategy

Once thermal runaway starts, it’s hard to stop. Prevention is the better bet. That means monitoring temps, replacing degraded thermal materials, and keeping cooling systems clean and functional.

And when damage is already done? Expert diagnostics stop runaway failures in their tracks. From burned-out semiconductors to scorched circuit boards, thermal runaway leaves a signature. The team at GES knows what to look for — and how to repair it before it leads to bigger losses. Now through the end of the month, we’re also offering 10% OFF single repairs or 15% OFF 3+ repairs on ABB products, including components damaged by thermal runaway.