06/0512
4.2.1 Current monitoring
The monitoring of the motor current supplements the functionality for the activation of
a holding brake. Applications demanding a holding brake accelerate the motor by the
specific load behavior when the brake is opened.
The asynchronous motor must be supplied with sufficient current in all operation
points in order to provide the necessary torque to avoid damage to property and per-
sons. Possible reasons for a lack of torque on the motor shaft can be a defective mo-
tor, a lack of or incorrect motor connection, a defect in the frequency inverter o
r
wrong parameterization. This is why the output current is monitored. If the absolute
value of the output current drops below the set threshold
Monitoring current 808,
the fault "F1310 minimum current monitorin
g" is triggered. In the event of a fault, the
holding brake is closed and the safety switch opened by the frequency inverter or an
external monitoring
Parameter Setting
No. Description Min. Max. Fact. sett.
808 Monitoring current 0.0 A o⋅I
FIN
0.2 ⋅ I
R
4.2.2 Frequency monitoring
The output frequency of the frequency inverter and the rotary frequency of the motor
shaft vary as a function of the load point. The selected control functions and methods
contain an estimate of the load point and thus the slip speed or a precise measure-
ment thanks to a speed sensor feedback. The standstill of the drive can thus be de-
termined precisely or also only estimated.
Reliable activation of the holding brake thus demands a
Frequency threshold 809
relative to the
Maximum frequency 419, from which the time t
13
for the closing of the
holding brake is measured.
Parameter Setting
No. Description Min. Max. Fact. sett.
809 Frequency threshold 0.0 % 100.0% 1.0 %
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