Siemens SIMATIC ET 200pro - Page 116

SIMATIC - ET 200pro motor starter
8-24 GWA 4NEB 950 5661-02 DS 04
Stop voltage
The parameter "stop voltage" sets the voltage value whereby run-down type
"voltage ramp" aborts the run-down, i.e. is switched off.
Current limitation value
The parameter "current limitation value" limits the start-up current to the param-
eterized value.
Duty cycle
The relative duty cycle in % is the ratio between the load duration and cycle
time for consumer units that are frequently switched off and on.
The duty cycle can be calculates according to the following formula:
Formula key:
• Duty cycle [%]
•t
s
start time [s]
•t
b
operation time [s]
•t
p
idle time [s]
The following graphic shows the operation.
Figure 8-13: Duty cycle
Switching frequency
To prevent a thermal capacity overload of the devices, the maximum permitted
switching frequency must be adhered to without fail. To this end, the parameter
"Response to overload – thermal motor model" must be deactivated (deactiva-
tion without restart). Furthermore, the idle time for the cooling down character-
istics of the thermal motor model must be disabled in the default setting = 0
(see Chapter 8.2.7 Parameters for idle time).
The following tables provide an overview of the switching frequencies / hour
according to the influencing factors.
ED
t
s
t
b
+
t
s
t
b
t
p
++
------------------------=
I
e
t
t
s
t
b
t
p