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17
Function library
17.1
Function blocks | L_MFail_1
1411
Lenze · 8400 HighLine · Reference manual · DMS 12.0 EN · 06/2017 · TD23
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17.1.102.3 Activating the mains failure control
The mains failure control is activated by setting
bFault
to TRUE. The inverter now generates the
required operational energy from the rotational energy of the drive. The drive is braked via the
power loss of the inverter and the motor. Thus, the speed deceleration ramp is shorter than for an
uncontrolled system (coasting drive).
After activating the mains failure control:
1. The acceleration time set in
is used to control the DC-bus voltage to the value at
nDCSet_a
.
2. At
nNOut_a
, an internally generated speed setpoint is output which serves to brake the drive to
a speed close to "0" (via the speed setpoint).
• Starting value for the controlled deceleration is the value at
nSet_a
. This input is
appropriately connected to the actual speed value
nMotorSpeedAct_a
of the
SB
• The speed deceleration ramp (and hence the braking torque) results from the moment of
inertia of the load machine(s), the power loss of the drive (system) and the set parameter
setting.
Stopping/cancelling the mains failure control
When
bFault
is reset to FALSE, an internal timing element is triggered. After the time set in
has elapsed, the mains failure control is stopped/cancelled.
• When the restart protection is active, the drive is continued to be braked to standstill.
• When the restart protection is active, the drive can only be reset by setting the
bReset
input
to TRUE.
• When the restart protection not active, the drive is accelerated to the speed setpoint.
Stop!
If a connected braking unit responds, the drive is braked with a max. possible torque
(I
max
). In this case, adapt the parameter setting if required (see the following chapter).
If the power section is not supplied, the drive cannot create a standstill torque
(important for active loads as e.g. hoists).