Beckhoff KL26 Series. KS26 Series, Документация

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Commissioning
KL26xx/KS26xx 41 Version: 2.5.0
4 Commissioning
4.1 Use of the relay terminals
NOTE
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.
4.1.1 KL2612 – service life
CAUTION
Observe the maximum values!
It is the maximum values that are to be expected that are critical to selection of the right terminal rather than
the technical figures for normal operation!
Fig. 23: KL2612 – characteristic curves