Lenze 9400 - Manual (Page 270)

7 Braking operation
7.2 Monitoring
270
Lenze · Servo-Inverter 9400 HighLine · Reference manual · DMS 10.0 EN · 11/2013 · TD05/06
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7.2.3 I2t utilisation - brake resistor
The controller is provided with a monitoring function of the I 2 t utilisation of the brake resistor
which is proportional to the converted braking power.
[7-2] Signal flow - I2t utilisation - brake resistor
• The monitoring function is based on the mathematical model which calculates the braking
current from the current DC-bus voltage and the brake resistance parameterised in C00129 .
• Hence, monitoring can be activated although no brake resistor is connected and can
therefore also be used for a testing mode to check the parameterisation.
• During the calculation, the thermal utilisation of the brake resistor on the basis of the following
parameters is taken into consideration:
• Resistance value ( C00129 )
• Continuous power ( C00130 )
• Thermal capacity ( C00131 )
• C00138 displays the calculated utilisation of the brake resistor in [%].
• A 100 % utilisation corresponds to the continuous power of the brake resistor which results
at the maximum permissible temperature limit of the brake resistor.
• The calculated utilisation is provided as oscilloscope signal Common.dnI2tBrakeResistor to
check the braking operation while the system is running
(scaling: 2
30 ≡ 100 %).
• If the utilisation exceeds the advance warning threshold set in C00572 , "Brake resistor: I2t >
C00572" is entered in the logbook and the response set in C00571 (default setting: "Warning")
is activated.

Note!
If the DC-bus voltage exceeds the overvoltage threshold due to a too high braking
energy, the monitoring function for overvoltage in the DC bus responds.  DC bus
overvoltage ( 272)

Note!
The braking operation will never be switched off by this monitoring function.
I2t
C00138 C00129
T = 0
Off
T = 1
On
100 %
C00572
C00571
C00574
C00129
C00130
C00131
Logbook entry " " Brake resistor: I2t > C00572
Logbook entry " " Brake resistor: I2t overload
U
DC_act
Temperature model
I =
Br
I
Br