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Functions, monitoring and protective functions
9.5 Monitoring functions and protective functions
Overload responses
The power module 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 module, since switching
losses account for a very 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 in output frequency (p0290 = 0, 2)
This response is recommended if pulse frequency reduction is not desired 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 quadratic torque characteristic with falling speed.
Reducing the output frequency has the effect of significantly reducing the drive output
current which, in turn, reduces losses in the power module.
● No reduction (p0290 = 1)
You should choose this option if it is not possible to reduce the pulse frequency or the
output current. With this response, the drive 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 drive 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
Parameters
• r0036
• r0037
• p0290
• r0293
• p0294
• r2135.13
• r2135.15
672
Thermal monitoring, power module
CO: Power module overload I
CO: Power module temperatures
Power module overload response
CO: Power module alarm threshold model temperature
Power module warning I
Fault: thermal overload in power module
Alarm: thermal overload in power module
t
2
t overload
2
Operating Instructions, 11/2017, A5E36652151A
Converter cabinet units
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