Mechanical wear

The number of mechanical operations has a low impact on the life of the main

contacts and their overall electrical life.

However general information concer ning mechanical wear could be of interest.

AC-Hum

Pollution of the magnet pole surfaces will create a slight hum coming from the

contactor in the closed position. When cleaning, use a soft and dry piece of cloth.

Hum can also occur if the pole surfaces are deformed. A louder hum will occur if

the shading coil (does not apply to AF) is broken because the magnet will cause the

contactor to chatter. If so the complete contactor needs to be exchanged.

Another reason for AC-hum could be corrosion caused by environmental conditions that

exceed the contactor specifications.Contactors need to be protected from conden

sation in order to keep the pole surfaces of the magnet free from corrosion.

For more specific information regarding this please see our technical catalog

1SBC1001122C0202. section: General Technical Data.

Contact bounce

The operational limit of the contactor is between 85 and 110% of the rated coil

voltage according to IEC60947-4-1. A voltage variation of ±5% of the above

limits will increase the contact bounce that leads to increased contact wear (does not

apply to AF with its electronic wide rangecoil). The reason for this is that higher

voltages will increase the speed of the electromagnet at closing. Lower voltages

will decrease the speed at closing. Both these factors can lead to a higher level of

contact bounce at closing. High voltage and the increased speed at closing also

contribute to some increased sound.