Lenze 9400 - Manual (Page 226)

5 Motor interface
5.9 Monitoring
226
Lenze · Servo-Inverter 9400 HighLine · Reference manual · DMS 10.0 EN · 11/2013 · TD05/06
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5.9.4 Motor phase failure monitoring
5.9.4.1 Monitoring of the individual motor phases during operation
Failure of one motor phase during operation
If a current-carrying motor phase (U, V, W) fails during operation, the response set in
C00597 is
executed (Lenze setting: "No response") if two conditions are fulfilled:
• Condition 1: Monitoring is activated
To safely detect a motor phase failure, a certain motor current must flow for the current sensor
system.
• Monitoring will therefore only be activated if, in the case of servo control the setpoint of the
motor current, and in the case of sensorless vector control or V/f control the actual value
motor current (display in C00054 ) has exceeded a certain current value.
• The current value for the activation can be set in C00599 in [%] with regard to the maximum
device current (display in C00789 ).
• Condition 2: A specific commutation angle was covered without the detection of a current flow.
In this case monitoring works according to the principle of checking for each motor phase that a
current flows depending on the commutation angle.
• Monitoring responds if a rotating field is output and hence a specific commutation angle
(approx. 150°, electric) is covered without the current having exceeded a (non-parameterisable)
threshold that depends on the device power.

Note!
• In case of sensorless vector control or V/f control, the safe detection of a motor phase
failure is only carried out if the actual current has exceeded the 3.5-fold value of the
threshold parameterised in C00599 .
• The dependence on the commutation angle also causes a dependence on the motor
type used:
• The commutation angle and the angle at the shaft (number of pole pairs) of a
synchronous machine are proportional. This makes it possible to predict which
shaft angle is maximally covered in case of error.
• An asynchronous machine has an additional slip between the commutation angle
and the angle on the shaft. This results in a load dependency due to which it is
impossible to predict the maximally covered shaft angle in the event of a fault.
In certain applications (e.g. hoists during lowering operation at non-zero speeds) it
may be possible that a rotating field is no longer applied. Instead, a DC current
flows. In this case, condition 2 is no longer met.