Technical data
8.7 Switching frequency
M200D PROFIBUS/PROFINET
Manual, 08/2014, A5E01577426A/RS-AA/004
175
The switching frequency specifies how many switching cycles can be performed in one time
unit (e.g. in 1 hour) with the switching device under normal operating conditions.
If motors are switched too often, this causes the thermal motor model to respond.
The maximum permissible switching frequency depends on the following operating data:
● Rated current I
e
of the motor
● ON duration ED
● Degree and category of protection
● Ambient conditions such as
– Temperature
– Installation position
The relative ON duration ED in % is the ratio between the load duration and the cycle
duration on loads that are switched on and off frequently.
The ON duration ED can be calculated using the following formula:
ED ON duration [%]
t
s
Starting time [s]
t
b
Operating time [s]
t
p
Idle time [s]
Graphics-based representation:
Figure 8-1 ON duration ED
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