Siemens SIMOTRAS 6SG7050 Operating Instructions Manual page 326

Function descriptions
9.10 Thermal overload protection of motor
2
(I t monitoring of motor)
The I 2 t monitoring function is parameterized in parameters P100, P113 and P114. If these parameters
are adapted correctly, the motor is protected against overloading (not all-round motor protection).
Adaptation
P114: A time constant T
parameter P114.
P113, P100: The permissible continuous current of the motor must be defined by parameters P100 and
P113.
The permissible continuous current is the product of the calculation P113 * P100.
Warning characteristic / switch-off characteristic
If the motor is loaded constantly, for example, with about 125% of the permissible continuous motor
current, then alarm A037 is triggered after a time constant (P114) has elapsed. If the load is not
reduced, then the drive is shut down when the switch-off characteristic is reached and fault message
F037 displayed.
Warning/switch-off times for other loads can be calculated from the diagram.
Alarm message triggering by motor I
This diagram shows how long it takes for an alarm 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
2,5
2
1,5
1
0,5
0
0
9-28
in minutes for the I
motor
0% preloading
80% preloading
0,5 1
Time / thermal time constant of motor
2
t monitoring function must be entered in
2
t monitoring function
1,5 2
0% preloading
20% preloading
40% preloading
60% preloading
80% preloading
2,5 3
SIEMENS AG 6SG7000-0BA76
SIMOTRAS HD Operating Instructions
01.04
3,5