Siemens SINAMICS G130 Operating Instructions Manual page 478

Functions, monitoring, and protective functions
9.4 Monitoring and protective functions
Overload responses
The power unit responds with alarm A07805. The Control Unit initiates the responses
assigned via p0290 at the same time that the alarm is issued. Possible responses include:
● Reduction in pulse frequency (p0290 = 2, 3)
T his is a highly effective method of reducing losses in the power unit, since switching
losses account for a high proportion of overall losses. In many applications, a temporary
pulse frequency reduction in favor of maintaining the process can be tolerated.
Disadvantage:
The pulse frequency reduction increases the current ripple, which can cause increased
torque ripple on the motor shaft (when moment of inertia is low) and increased noise
level. Reducing the pulse frequency does not affect the dynamic response of the current
control circuit, since the sampling time for the current control circuit remains constant.
● Reduction of the output frequency (p0290 = 0, 2)
This version is recommended if you do not need to reduce the pulse frequency or if the
pulse frequency has already been set to the lowest level. Further, the load should also
have a characteristic similar to a fan, that is, a square law torque characteristic with
decreasing speed. Reducing the output frequency has the effect of significantly reducing
the converter output current which, in turn, reduces losses in the power unit.
● No reduction (p0290 = 1)
You should choose this option if it is not possible to reduce the pulse frequency or the
output current. The converter does not change its operating point once an alarm
threshold has been overshot, which means that the drive can be operated until it reaches
its shutdown values. Once the shutdown threshold is reached, the converter switches off
with an "overtemperature" or "overload" fault. The time until shutdown, however, is not
defined and depends on the degree of overload. Only the alarm threshold can be
changed so that an alarm is received earlier and, if necessary, steps can be taken to
intervene in the drive process (e.g., reduce the load, reduce the ambient temperature).
Function diagram
FP 8014
Parameter
• r0036
• r0037
• p0290
• r0293
• p0294
• r2135.13
• r2135.15
478
Thermal monitoring, power unit
CO: Power unit overload I2t
CO: Power unit temperatures
Power unit overload response
CO: Power unit alarm threshold model temperature
Power unit alarm I2t overload
Fault thermal overload power unit
Alarm, thermal overload power unit
Inverter chassis units
Operating Instructions, 07/2016, A5E00331449A