Use of the relay terminals

Smooth operation

It is extremely important to observe the technical specifications if fault-free operation of the relay terminal is to be guaranteed. Every exceedance of the factors specified in the technical data can lead to premature contact ageing or even welding.

If relays are to be used in a control system the expected operating conditions must be analyzed with great care.

  • Switching capacity, service life (switching cycles) and the number of switches per minute must be considered.
  • Appropriate protective circuits must be used to protect the relay contacts from excessive voltage peaks such as can occur when switching inductive loads (contactors, motors etc.). This allows switching frequencies nearly equal to those appropriate to ohmic loads to be achieved.
  • Arcing time when switching DC loads are significantly longer than those for comparable AC voltages (zero crossing); material flow can result.
  • If the terminal is used to change the direction of inductive loads, adequate dead-times during the switch-over must be provided, in order to avoid temporary short-circuits.