FAQ02801 of General Purpose Relays FAQ

There are two main types of maintenance: corrective maintenance (i.e., inspections and replacements that are performed after a failure has occurred) and preventative maintenance (i.e., inspections and maintenance that are performed before a failure occurs).

Some of the important issues with preventative maintenance is when to perform inspections and replacements, how to know when that is required, and how to determine the timing.

The factors that must be considered when determining maintenance schedules for Relays is the level of importance of the target device, and the required reliability level, when looking at maintenance from the device or system perspective. There are also different types of failure for the different characteristics and items based on the type of Relays.

Relays failure types can be broadly classified into failures from wear, typified by worn out contacts, and deterioration failures, such as layer shorts in coil windings.

In general, once the conditions of use for the Relays have been determined, it is possible to predict maintenance requirements because types of wear, such as contact wear, and the timing of wear related failures are related to the number of operations. On the other hand, deterioration failures, such as layer shorts in coil windings, are greatly affected by the inherent reliability of the Relays being used. The maintenance requirements are affected by use reliability, e.g., operating conditions and on-site environment.

This means that the failures are often different for each case, which makes it difficult to determine a maintenance schedule in advance.

In actual operation, wear and deterioration progress at the same time and it is important to know which type of failure is going to occur first when determining maintenance schedules.

The following items are useful for reference when determining maintenance timing.