Insulation Failure of a Cabinet Due to Water Ingress
Background
Water ingress tests are required when a product is specified for use in a wet or humid environment, and they refer to the unwanted intrusion of water/moisture into the product or components designed to be dry.
The standard EN 60529 defines how a product is tested by its classification for water resistance, which ranges from small droplets to full immersion.
The presence of unwanted water can compromise electrical insulations and, in some cases, can cause internal condensation , ultimately leading to system failure and electrical hazards. Materials that may have insulating properties are chosen based on their ability to perform in a dry environment. Still, when exposed to moisture or direct water intrusion, they will fail and cause a variety of hazards.
Incident Description
Recently, a customer had a failure of an electrical cabinet that was designed for installation outdoors. It has a water IP rating of 4, which is sufficient for such environments; however, the cabinet circuit breakers kept tripping, and water ingress was found on the internal components.
Analysis of the Failure
The customer sent a representative sample for evaluation and also supplied comprehensive photos of the installed cabinet.
An IPX4 test allows water to enter the product. Still, it must not be sufficient to interfere with the operation of the product, reach live parts/insulation, or the ends of cables, or accumulate where it may reduce the creepages of a circuit.
The sample was tested for IPX4 as required by the standard using the spray head due to the size of the equipment.
The results showed that there was some ingress; however, it was not enough to warrant a failure.
After much more investigation, the root cause was identified within one of the supplied photos. The cabinets had louvres to assist in the cooling of the electrical components. These were fitted in the correct orientation; however, it seems that after some routine maintenance on the installed cabinet, the internal filter that sits behind the louvre was removed but not re-fitted.
This filter was a key part in preventing the water ingress to the control gear; it did not entirely stop the ingress, but it did stop the water from being sprayed directly onto the internal circuits.
The representative sample was re-tested with the internal filter removed, and the failures that were observed in the installed cabinet were replicated.
Lessons Learned
This case highlights that a manufacturer can design a product to be resistant to environmental factors and can pass the relevant tests. Still, once installed, the responsibilities of continued compliance may fall into the hands of the maintenance team.
Conclusion
Failure due to water ingress can cause safety issues, product malfunction, and in some cases, the reputation of a manufacturer can be at risk if there are customer complaints.
Although the manufacturer has produced a cabinet that has passed all the requirements for environmental tests, these tests are typically performed in a laboratory environment on a new production sample.
Although regular servicing is an essential part of maintenance, it must be ensured that the service personnel are also responsible for the continued compliance of a product once it has been installed and commissioned.
Enquire Here
