Why Summer Is the Hardest Season on Your Industrial Drives07/16/2026 Every summer, industrial electronic repair shops see the same spike: variable frequency drives (VFDs) that ran fine all winter suddenly begin failing in July and August. This isn't a coincidence. Summer brings two major threats that attack drives from opposite directions: sustained heat and violent lightning storms. A drive that survives one can still be taken out by the other. Here's what's happening inside your control panels as temperatures rise, and what you can do to keep your equipment running throughout the season. Heat: The Slow Killer Every time a VFD controls a motor under load, the power transistors (IGBTs) in the output stage dissipate a significant amount of heat. The harder the motor works, the more heat those components generate. The drive is designed to handle that heat—but only if it has an effective way to remove it. When it doesn't, damage accumulates quietly over weeks and months. • The output section runs hotter than rated. Most VFDs are designed for a maximum ambient temperature of approximately 40°C (104°F). Manufacturers are clear that exceeding this limit increases the risk of premature failure [3]. To protect themselves, many drives automatically derate, reducing the output current they can deliver as temperatures climb [3][4]. • Cooling can't keep up. A clogged filter, dirty heat sink, or failing cooling fan prevents heat from escaping the enclosure, pushing internal temperatures beyond the conditions the drive was designed to withstand. • Components age faster. Electrolytic capacitors are among the most heat-sensitive components in a drive. Their service life follows the Arrhenius law of chemical aging: every 10°C increase above the rated temperature can reduce capacitor life by roughly half [1][2]. Danfoss cites a similar rule of thumb for the drive's electronics as a whole [3]. The result is premature failure. A drive that should have lasted ten years may fail in five, often with very little warning. Lightning: The Fast Killer While heat causes damage gradually, summer storms can destroy a drive in microseconds. A direct lightning strike is uncommon—the greater threat is a transient voltage surge. These surges travel through power conductors or are induced into nearby wiring whenever lightning strikes in the surrounding area [5]. Those voltage spikes seek out the most sensitive electronic components inside the drive: • Input rectifier and DC bus: A severe surge can destroy the semiconductor diodes that convert AC power to DC while also damaging the DC bus capacitors. • Control power supply and logic boards: Even a relatively small induced surge can destroy the low-voltage electronics responsible for operating the drive. • Surge protection devices: Metal-oxide varistors (MOVs) are sacrificial by design. Every surge they absorb reduces their ability to protect against future events [6]. The IEEE surge standard classifies surge environments by location. The closer equipment is to the building's service entrance, the greater the surge energy it must withstand. That's why best practice is to use staged surge protection, with one SPD at the service entrance and additional protection at distribution panels or drive cabinets [5]. SPDs cannot stop lightning, but they provide a safer path for surge energy than your drive. Preventive Maintenance: What Actually Helps The goal is simple: allow the drive to shed heat efficiently and provide surge energy with a safe path to ground. • Clean or replace panel filters. • Blow out heat sinks. • Remove conductive metal shavings carefully. • Verify cooling fan operation. Cooling fans are inexpensive wear items, and replacing one before it fails is far less expensive than replacing the drive it protects. • Inspect surge protection devices and replace any that have reached the end of their service life. Safety First: LOTO Before You Open Anything No maintenance task is worth risking an injury. Before opening any electrical panel, follow your company's lockout/tagout (LOTO) procedures. Drives can retain hazardous voltage in their DC bus capacitors even after power has been removed, so always verify de-energization and allow sufficient discharge time before servicing. When Heat or Lightning Wins Sometimes the damage has already been done—whether a drive has been slowly overheating all summer or was hit by a severe power surge during a storm. Fortunately, many heat- and surge-damaged drives can be repaired, even when they are obsolete and no direct replacement is available. Repairing your existing drive avoids many of the complications associated with replacement, including production delays, panel modifications, wiring changes, and the need to recreate years of programming and tuning. At Precision Electronic Services, we've been repairing industrial drives and electronics since 1985. We make every effort to preserve your existing programming so your repaired drive returns ready for service. Component-level repairs are often faster and more cost-effective than replacing the entire unit. If heat or lightning has damaged your drive beyond repair, we'll help you find the right replacement as quickly as possible. Sources & Further Reading 1. Nippon Chemi-Con — Lifetime of Aluminum Electrolytic Capacitors (Arrhenius law; lifetime approximately halved for every 10°C rise in temperature): https://www.chemi-con.co.jp/en/faq/detail.php?id=alLifetime 2. Nichicon — Estimated Life Calculator for Capacitors (Arrhenius equation; life halved for every 10°C increase in temperature): https://www.nichicon.com/en-us/design-support/lifetime-calculator/ 3. Danfoss — It's a Harsh World, Part 4: Drives vs. High Temperatures (typical 40°C rating; exceeding it risks premature failure; ~50% lifetime reduction per 10°C above rated maximum; output-current derating): https://www.danfoss.com/en/about-danfoss/articles/dds/it-s-a-harsh-world-part-4-drives-vs-high-temperatures/ 4. Yaskawa — Current Derating for 1000-Series Drives (Application Note AN.AFD.29; derating by ambient temperature, carrier frequency, and altitude): https://www.yaskawa.com/delegate/getAttachment?documentId=AN.AFD.29&cmd=documents&documentName=AN.AFD.29.pdf 5. IEEE Std C62.41 — Recommended Practice on Surge Voltages in Low-Voltage AC Power Circuits (lightning and switching transients as surge origins; surge-environment location categories relative to the service entrance): https://standards.ieee.org/ieee/C62.41/2856/ 6. Northeastern University — Overvoltage and Surge Protection in Variable Frequency Drives (MOV behavior and degradation under repeated surges in VFD applications): https://repository.library.northeastern.edu/files/neu:bz60cx50k/fulltext.pdf Back To Blog
Why Summer Is the Hardest Season on Your Industrial Drives07/16/2026 Every summer, industrial electronic repair shops see the same spike: variable frequency drives (VFDs) that ran fine all winter suddenly begin failing in July and August. This isn't a coincidence. Summer brings two major threats that attack drives from opposite directions: sustained heat and violent lightning storms. A drive that survives one can still be taken out by the other. Here's what's happening inside your control panels as temperatures rise, and what you can do to keep your equipment running throughout the season. Heat: The Slow Killer Every time a VFD controls a motor under load, the power transistors (IGBTs) in the output stage dissipate a significant amount of heat. The harder the motor works, the more heat those components generate. The drive is designed to handle that heat—but only if it has an effective way to remove it. When it doesn't, damage accumulates quietly over weeks and months. • The output section runs hotter than rated. Most VFDs are designed for a maximum ambient temperature of approximately 40°C (104°F). Manufacturers are clear that exceeding this limit increases the risk of premature failure [3]. To protect themselves, many drives automatically derate, reducing the output current they can deliver as temperatures climb [3][4]. • Cooling can't keep up. A clogged filter, dirty heat sink, or failing cooling fan prevents heat from escaping the enclosure, pushing internal temperatures beyond the conditions the drive was designed to withstand. • Components age faster. Electrolytic capacitors are among the most heat-sensitive components in a drive. Their service life follows the Arrhenius law of chemical aging: every 10°C increase above the rated temperature can reduce capacitor life by roughly half [1][2]. Danfoss cites a similar rule of thumb for the drive's electronics as a whole [3]. The result is premature failure. A drive that should have lasted ten years may fail in five, often with very little warning. Lightning: The Fast Killer While heat causes damage gradually, summer storms can destroy a drive in microseconds. A direct lightning strike is uncommon—the greater threat is a transient voltage surge. These surges travel through power conductors or are induced into nearby wiring whenever lightning strikes in the surrounding area [5]. Those voltage spikes seek out the most sensitive electronic components inside the drive: • Input rectifier and DC bus: A severe surge can destroy the semiconductor diodes that convert AC power to DC while also damaging the DC bus capacitors. • Control power supply and logic boards: Even a relatively small induced surge can destroy the low-voltage electronics responsible for operating the drive. • Surge protection devices: Metal-oxide varistors (MOVs) are sacrificial by design. Every surge they absorb reduces their ability to protect against future events [6]. The IEEE surge standard classifies surge environments by location. The closer equipment is to the building's service entrance, the greater the surge energy it must withstand. That's why best practice is to use staged surge protection, with one SPD at the service entrance and additional protection at distribution panels or drive cabinets [5]. SPDs cannot stop lightning, but they provide a safer path for surge energy than your drive. Preventive Maintenance: What Actually Helps The goal is simple: allow the drive to shed heat efficiently and provide surge energy with a safe path to ground. • Clean or replace panel filters. • Blow out heat sinks. • Remove conductive metal shavings carefully. • Verify cooling fan operation. Cooling fans are inexpensive wear items, and replacing one before it fails is far less expensive than replacing the drive it protects. • Inspect surge protection devices and replace any that have reached the end of their service life. Safety First: LOTO Before You Open Anything No maintenance task is worth risking an injury. Before opening any electrical panel, follow your company's lockout/tagout (LOTO) procedures. Drives can retain hazardous voltage in their DC bus capacitors even after power has been removed, so always verify de-energization and allow sufficient discharge time before servicing. When Heat or Lightning Wins Sometimes the damage has already been done—whether a drive has been slowly overheating all summer or was hit by a severe power surge during a storm. Fortunately, many heat- and surge-damaged drives can be repaired, even when they are obsolete and no direct replacement is available. Repairing your existing drive avoids many of the complications associated with replacement, including production delays, panel modifications, wiring changes, and the need to recreate years of programming and tuning. At Precision Electronic Services, we've been repairing industrial drives and electronics since 1985. We make every effort to preserve your existing programming so your repaired drive returns ready for service. Component-level repairs are often faster and more cost-effective than replacing the entire unit. If heat or lightning has damaged your drive beyond repair, we'll help you find the right replacement as quickly as possible. Sources & Further Reading 1. Nippon Chemi-Con — Lifetime of Aluminum Electrolytic Capacitors (Arrhenius law; lifetime approximately halved for every 10°C rise in temperature): https://www.chemi-con.co.jp/en/faq/detail.php?id=alLifetime 2. Nichicon — Estimated Life Calculator for Capacitors (Arrhenius equation; life halved for every 10°C increase in temperature): https://www.nichicon.com/en-us/design-support/lifetime-calculator/ 3. Danfoss — It's a Harsh World, Part 4: Drives vs. High Temperatures (typical 40°C rating; exceeding it risks premature failure; ~50% lifetime reduction per 10°C above rated maximum; output-current derating): https://www.danfoss.com/en/about-danfoss/articles/dds/it-s-a-harsh-world-part-4-drives-vs-high-temperatures/ 4. Yaskawa — Current Derating for 1000-Series Drives (Application Note AN.AFD.29; derating by ambient temperature, carrier frequency, and altitude): https://www.yaskawa.com/delegate/getAttachment?documentId=AN.AFD.29&cmd=documents&documentName=AN.AFD.29.pdf 5. IEEE Std C62.41 — Recommended Practice on Surge Voltages in Low-Voltage AC Power Circuits (lightning and switching transients as surge origins; surge-environment location categories relative to the service entrance): https://standards.ieee.org/ieee/C62.41/2856/ 6. Northeastern University — Overvoltage and Surge Protection in Variable Frequency Drives (MOV behavior and degradation under repeated surges in VFD applications): https://repository.library.northeastern.edu/files/neu:bz60cx50k/fulltext.pdf