4.2 Power failure bridging
4.2.1 Detection of a voltage failure
The mains failure support feature detects a failure of at least two phases of the mains
supply. If no countermeasures are taken, this failure will cause a drop in the DC link
voltage and thus lead to the device being switched off.
In the event of a power failure, the DC link voltage can be supported by using the
motor’s rotational energy. To this end, the motor will be operated as a generator and
decelerated in a controlled manner in the event of a power failure so that a
configurable DC link voltage setpoint will be maintained. This function is especially
useful when it comes to powering the electronics in drives with magnetic bearings,
as this will prevent the assembly from crashing into the safety bearing in the event of
a power failure all the way to the lowest possible speeds.
NOTE
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Please note that the components which need bridging must be
powered via the DC link (DC power supply). In particular, the
power supply of the drive controller itself (24 V control voltage)
must be ensured.
Image 4.2: Power failure bridging settings screen
ID No.: 0842.26B.5-01 Date: 09.2020
ServoOne - Device Help
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4 Power stage
4.2.1.1 Functional description
The P 2940 - CON_PowerFail_Sel selection parameter can be used to select the
following operating modes:
0= (OFF) switched off
1= (Ret) Power failure bridging with power return detection. The system will start up
again if the power returns within a configurable period of time.
2= (NoRet) Power failure bridging with power return detection. The system will not
start up again.
3= (NoLim) Fastest possible speed reduction without power return detection.
4 = (VFC_NoLim) Only with HF function package; please refer to the “Power failure
bridging” section in the “HF function package” User manual (ID No.: 1107.22B.x)
5= (RetAbs) Same as 1=Ret, but with absolute voltage levels and without validation
check.
6= (NotRetAbs) Same as 2=NoRet, but with absolute voltage levels and without
validation check.
7= (NoRetAbsPulse) Same as 6=NoRetAbs, but with pulse operation.
NOTE
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For information on the advanced V/Hz mode, see the “HF function
package" User manual (ID No.:1107.22B.x).
