The control cabinet - the inconspicuous heart of every electrical system, often hidden away in plant rooms or on hall walls. But while we keep a close eye on the service life of machines and production systems, the question of the ageing of switch cabinets often remains unanswered. When is an enclosure really old? And which factors have a decisive influence on its service life?
Components age at different rates
An enclosure does not age as a whole, but rather component by component - and at surprisingly different rates. While robust metal enclosures can easily last 30 years or more, there are other elements that show signs of ageing much earlier:
- Relays and contactors: 100,000 to 1 million switching cycles, depending on load
- PLC modules: Typical service life 10-15 years
- Power supply units and power supplies: Often critical after 7-10 years
- Fan and air conditioning: Often problematic after 5-8 years
- Capacitors: Depending on type and ambient temperature 5-15 years
A particularly revealing example: Several systems in a production plant were experiencing sporadic faults. The cause was found in the power supply units of the control units - all of which were from the same procurement round nine years ago and were now showing signs of age-related failure.
What factors accelerate ageing?
The calendar time is only one of several factors that determine the actual "ageing" of an enclosure:
Ambient temperature: Every 10°C increase halves the service life of electronic components - an often underestimated rule of thumb. Switch cabinets without sufficient air conditioning in warm production areas therefore often age twice as quickly as comparable installations in air-conditioned rooms.
Humidity and dust: Particularly in production environments with a high particle load or humidity, switch cabinets show accelerated signs of ageing. Here, the effective service life can be reduced by 30-40%.
Switching frequency: Mechanical components such as relays or contactors age primarily through use, not through time. A relay in a rarely switched system can last 20 years - the same component in a system with frequent switching operations may only last 2-3 years.
The four warning signals for ageing control cabinets
How do you recognize that your switch cabinet needs a makeover? Look out for these signs:
- Thermal abnormalities: Local heat zones or unusual temperature distribution
- Accumulation of component failures: Especially if similar components are affected
- Increasingly sporadic faults: Often an indication of ageing electronic components
- Corrosion or mechanical damage: Especially at connection points
Act proactively instead of repairing reactively
A forward-looking modernization strategy for control cabinets can minimize failure risks and optimize costs:
- Selective component replacement: Preventively replace critical components
- Condition-based maintenance: Regular thermographic examinations
- Documented ageing strategy: Record service life expectations of all important components
Investing in systematic monitoring and scheduled modernization of enclosures pays off many times over thanks to reduced downtimes and avoided emergency repairs. And best of all, modern CAE tools such as EPLAN allow the modernization process to be planned and documented smoothly - for enclosures that do not age, but are continuously rejuvenated.
