Contact Protection Measures - Profimess SW-08 Operating Instructions Manual

Installation and initial startup

Contact protection measures

Fig. 26: Pin assignment, plug socket,
Change-over contact (Form 30x70)
5.9 Contact protection
measures
The Reed-switches used in the switch
contacts are designed to be very sensi-
tive to overload. To prevent destruction
of the switch contact, the values speci-
fied on the rating plate of the switch
contact housing must never be
exceeded (not even temporarily).
There is a risk of overload from:
n inductive loads
n capacitive loads
ohmic loads.
n
Suitable measures must be taken to
protect against overload (see following
examples):
42
Inductive load
There is danger of voltage peaks from
inductive loads when switching off (up
to 10 times the rated voltage). Induc-
tive loads are caused by, e.g.:
n Contactors, relays
n Solenoid valves
n Electric motors
Examples of protective measures:
Fig. 27: Example 1
Fig. 28: Example 2
Capacitive loads
There is a danger of high current
peaks from capacitive loads when
switching-on the switch contact
(exceeding rated current). Capacitive
loads are caused by, e.g.:
Long connecting cables
n
Capacitive consumers
n
Example of protective measure:
23.02.2015