Lenze 8400 motec - Manual (Page 177)

Lenze · 8400 motec · Reference manual · DMS 4.1 EN · 08/2013 · TD05 177
5 Motor control (MCTRL)
5.14 Monitoring
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
5.14.4 Brake resistor monitoring (I2xt)
Due to the converted braking power, the brake resistor is thermally stressed and can even be
thermally destroyed by excessive braking power.
The monitoring of the I 2 xt utilisation of the controller serves to protect the brake resistor. It acts in
proportion to the converted braking power.
• If the I 2 xt utilisation reaches the switch-off threshold set in C00572 :
• The error response set in C00574 will take place.
• The " OC12: I2xt brake resistor overload " error message is entered into the Logbook.
• If the system is dimensioned correctly, the monitoring should not be activated. If individual
pieces of rated data of the actually connected brake resistor are not known, they have to be
identified.
• If the DC-bus voltage exceeds the overvoltage threshold due to a braking energy that is too high,
the monitoring for overvoltage in the DC bus is activated ("OU: DC-bus overvoltage" error
message).
Temperature model
[5-20] Signal flow for monitoring the brake resistor

Danger!
In the Lenze setting ( C00574 = "1: Fault"), the response of the monitoring function stops
the braking operation.
In particular for applications such as hoists, check if a stopping of the braking operation
due to the setting of C00574 = "1: Fault" is permissible.

Stop!
Implement appropriate protective measures against thermal overload of the brake
resistor!
Examples:
• Parameterisation of an error response in C00574 and evaluation of the parameterised
error message within the application or the machine control system.
• Interruption of the mains supply by means of the temperature contact at the brake
resistor and a simultaneous activation of the mechanical brake.
• Evaluating the temperature contact at the brake resistor by the motor PTC input of
the controller.
 Error message: " OC12: I2xt overload brake resistor "
J
C00138
C00130
C00131
I
Br
I = 1
On
I = 0
Off
I xt 2
C00572 C00574
C00129
)
temperature model