Function library
Function blocks
9.2.41 Mains failure control (MFAIL)
9-149
L
EDSVS9332S-D11 EN 3.0
Activation
z MFAIL-FAULT = HIGH activates the mains failure control.
z MFAIL-FAULT = LOW triggers a timing element. After the time set under C0983 has elapsed,
the mains failure control is completed/cancelled (see description of mains recovery, Chapter
9.2.41.6).
– The drive is accelerated to the speed setpoint if the restart protection is not active.
– The drive is still decelerated to zero speed, if the restart protection is active (see description
about the restart protection, Chapter 9.2.41.3).
– If the restart protection is active, the drive can only be reset by a HIGH level signal at the
MFAIL-RESET input.
Function
The controller gains the required energy from the rotational energy of the driven machine. The driven
machine is braked via the power loss of the controller and the motor. The speed deceleration ramp
is shorter than for an uncontrolled system (coasting drive).
With the activation,
z the DC bus voltage is controlled to the value at the MFAIL-DC-SET input.
z an internally generated speed setpoint is output at the MFAIL-N-OUT output. The drive can
thus be braked to zero speed (via the speed setpoint).
– The value at input MFAIL-SET is the start value for the controlled deceleration. This input is
generally connected to the output MCTRL-NACT (actual speed) or MCTRL-NSET2,
MFAIL-NOUT (speed setpoint).
– The speed deceleration ramp (and thus the brake torque) results from the moment of inertia
of the driven machine(s), the power loss, and the parameterization.
Stop!
z If a connected brake unit is activated, the drive is braked with the maximum possible torque
(Imax). In this case, it may be necessary to adapt the parameterization (see description of the
parameterization).
z If the power stage is not supplied, the drive cannot generate a standstill torque (important for
active loads such as hoists).
Parameter setting
The parameters to be set depend strongly on the motor used, the inertia of the driven machine and
the drive configuration (single drive, drive network, master - slave operation, etc.). This function must
therefore be adapted to the individual application in every case.
The following specifications refer to Chapter 9.2.41.1
Important settings prior to the initial set-up:
1. Save the previous setting in a parameter set (e.g. parameter set 4)
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