The Most Common Automatic Transfer Switch Faults and What Causes Them

A correctly functioning automatic transfer switch responds swiftly in case the main source of power gets cut off, automatically shifting the electrical load from the main to the generator. In case the system functions perfectly, there won’t be any problems, but faulty systems mean that everything will fail at the most critical times. 

At Blades Power Generation, we often find that many ATS problems come down to maintenance, environmental conditions, or incorrect installation rather than the switch itself. 

Contact Wear and Burnt Connections 

The most frequent fault encountered is that the contactors within the switchgear are worn. This situation can be caused by: 

Failure to address this issue can result in delayed switching or even total switching failure. In the business environment where generators undergo periodic testing, wear develops more quickly. 

Battery and Starting Issues 

In such instances, the fault may be attributed to the transfer switch, while actually it lies with the generator starting system. 

Flat battery, faulty charger, or starter connections could prevent the generator from spinning at its rated speed and, hence, the ATS would recognise an unstable source and not transfer the load. 

This issue is especially common with older or poorly maintained used generators that may spend long periods sitting idle between outages. 

Moisture and Condensation 

The UK climate can be unforgiving on electrical equipment. The formation of condensation within enclosures can lead to: 

In open systems lacking IP-compliant enclosures, winter and coastal climates pose an increased risk of such issues. 

At Blades Power Generation, we always recommend checking enclosure condition and ventilation as part of routine inspections. 

Incorrect Voltage Sensing 

An ATS relies on voltage monitoring to know when to transfer between mains and generator power. 

Incorrect setting up of the sensing parameters can result in the following: 

That is why it is essential to commission an installation properly. Even top-of-the-range switches can work improperly due to incorrect settings. 

Lack of Routine Testing 

Perhaps the biggest problem of all is simply neglect. 

Many systems are installed and forgotten about until a real power cut happens. By then, seized mechanisms, weak batteries, or damaged components may already be waiting to cause trouble. 

Regular testing helps identify small problems before they turn into complete failures. 

At Blades Power Generation, we believe reliable backup power starts with proper maintenance, sensible installation, and equipment designed for real operating conditions. A well-maintained ATS should provide dependable service for many years without unnecessary complexity.