Causes of inverter and servo amplifier failure and lifespan
The manufacturer's designed lifespan of an inverter is said to be approximately 10 years, but the factors that determine this lifespan are thought to be the following parts.
- Cooling fan
(Self-cooling fan) failure - power supply smoothing aluminum
Electrolytic capacitor failure - Aluminum for control circuit
Electrolytic capacitor failure - Contact for inrush current suppression circuit
(Thyristor/relay) failure
etc.
The deterioration and failure of these parts over time affects the lifespan of the inverter and servo amplifier, but in fact "heat" has a major impact on the deterioration and failure of these cooling fans and capacitors. Therefore, measures to deal with heat are important for stable use of inverters and servo amplifiers.
Learn the basics of heat problems and how to solve them!
A 24-page resource focusing on thermal issues in panel.
Heat-related problems in panel and how to solve them
We will introduce you to the following.
Periodic replacement of parts with limited lifespan
The Japan Electrical Manufacturers' Association (JEMA)'s "Recommendations for Periodic inspections of General-Purpose Inverters" lists the following guidelines for periodic replacement of inverter parts: Because parts have a lifespan, neglecting periodic replacement will cause the inverter to break down.
Guidelines for periodic inspections and part replacement of inverters (excerpted from "Recommendations for periodic inspections of general-purpose inverters")
| Part Name | inspections items | inspections cycle | Standard replacement period | Exchange method and other details |
|---|---|---|---|---|
| Cooling fan | Are there any abnormal vibrations or sounds? | everyday life | 2-3 years | Replace with a new one |
| Is there any looseness in the connections? | 1年 | |||
| Cleaning the air filter | 1年 | |||
| Smoothing capacitor | Is there any leakage? | 1 year | 5年 | Replace with a new one |
| Is the navel (safety) visible? Is there any swelling? |
1年 | |||
| relay | Is there any rattle noise during operation? | 1年 | ー | To be determined after investigation |
Aluminum electrolytic capacitors and heat countermeasures
According to Arrhenius' law, the lifespan of an aluminum electrolytic capacitor is halved for every 10°C increase in temperature. The design lifespan of an aluminum electrolytic capacitor inside an inverter is based on use at approximately 40°C. If the temperature of an aluminum electrolytic capacitor inside an inverter in panel without cooling measures reaches 50°C, 60°C, or 70°C, the inverter's lifespan will be accelerated to 1/2, 1/4, or 1/8, shortening the inverter's lifespan and leading to breakdowns and equipment shutdowns.
Cooling fan (self-cooling fan) and heat countermeasures
The expected lifespan of the DC fan motor itself installed in the inverter is approximately 100,000 hours at 40°C, but this lifespan shortens above 40°C, and at 60°C the expected lifespan is reduced to just under 50,000 hours, roughly half the expected lifespan.
The design life of a motor is greatly affected by the bearing life, which is expressed as the grease life and mechanical life, but the bearing life is almost entirely dependent on the grease life caused by heat and temperature. It is said that if the bearing temperature rises by 15°C, the bearing grease life will be halved.
Note: From Oriental Motor Co., Ltd. technical information
https://www.orientalmotor.co.jp/tech/reference/life01/
https://www.orientalmotor.co.jp/tech/reference/life06/
