Siemens 6RA7086-6KS22 Operating Instructions Manual page 388

Function descriptions
Fault message triggering by motor I
This diagram shows how long it takes for a fault message to be triggered if, after a long preloading
period (> 5 * T_th), a new constant load value is injected abruptly.
T_th = P114 .. thermal time constant of motor
5
4,5
4
3,5
3
2,5
2
1,5
1
0,5
0
0
CAUTION
When the electronics power supply fails for longer than 2 s, the calculated motor preloading
value is lost. When the supply is reconnected, the system assumes that the connected motor
has not been loaded at all!
If the electronics power supply fails and the converter is switched on again within 2 s (e.g. via
the "Automatic restart" function), then the temperature calculation is based on the last calculated
2
l t value of the motor..
2
The I t monitoring function reproduces only a rough thermal image of the motor, i.e. it does not
provide all-round motor protection.
If P114 (T
motor
9-32
0,5 1
Time / thermal time constant of motor
) is set to zero, then the I
2
t monitoring function
1,5
2
t monitoring function is deactivated.
0% preloading
20% preloading
40% preloading
60% preloading
80% preloading
2 2,5
SIEMENS AG
SIMOREG DC Master
05.05
3
6RX1700-0AD76
Operating Instructions