Operating instructions

6-34 Mounting and Installation Rexroth IndraDrive
DOK-INDRV*-FU*********-IB01-EN-P
General Measures of Radio Interference Suppression for Relays,
Contactors, Switches, Chokes, Inductive Loads
If, in conjunction with electronic devices and components, inductive loads,
such as chokes, contactors, relays are switched by contacts or
semiconductors, appropriate interference suppression has to be provided
for them. In the case of d.c. operation, this is achieved by arranging free-
wheeling diodes and in the case of a.c. operation, by arranging usual RC
interference suppression elements depending on the contactor type,
immediately at the inductance. Only the interference suppression element
arranged immediately at the inductance serves this purpose. Otherwise
the emitted noise level is too high which can affect the function of the
electronic system and of the drive.
If possible, mechanical switches and contacts should only be realized as
snap contacts. Contact pressure and contact material must be suited for
the corresponding switching currents.
Slow-action contacts should be replaced by snap switches or by solid-
state switches, because slow-action contacts strongly bounce and are in
an undefined switching status for a long time which emits electromagnetic
waves in the case of inductive loads. These waves are an especially
critical aspect in the case of manometric or temperature switches.