KEB COMBIVERT F5-A Applications Manual page 411

Protective functions
function active" (POFF). Attention:Motor warming! A reset is necessary for the restart.
Pn.44 bit 3...4 = 1:
The inverter modulates independent of a set direction or rotation with the adjusted boost and is in status "78:
power off function active" (POFF). After expiration of the restart delay Pn.52 (if adjusted) the inverter restarts
automatically when the mains voltage is returned.
Pn.44 bit 3...4 = 2:
The inverter switches off the modulation and is in status "84: no direction of rotation after power off" (PLS). A
reset is necessary for the restart.
Restart delay (Pn.52)
If a restart is allowed the restart delay time is kept constant after power recovery of the output value. It is ad-
justable within the range of 0...100 s (Default 0 s). After expiration of this time it is accelerated again onto the
current setpoint.
Power off start inp.sel. (Pn.49)
Only hardware inputs can be adjusted with this parameter, since these inputs are scanned in the same cycle
where the power off control is active. A setting via the control word or di.01/02 is not possible.
Examples of the power off-operating modes
To better illustrate the context, the operating modes are explained in more detail in the following section.
Bridging of mains gaps (not for vector controlled operation with DSM)
Setpoint source: Starting voltage (Pn.44 bit 6..7 = 0)
Voltage setpoint Pn.50, if base value < Pn.48 (Pn.44 bit 6..7 = 2)
In this mode the motor shall be operated almost in no-load operation and only the energy, the inverter requires
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for operation should be regenerated. The starting voltage is simultaneously the setpoint of the DC-link voltage
controller. In v/f-characteristic operation, the set value is the setpoint of the active current controller, and in
vector controlled operation, the torque limit of the speed controller.
In case of weak supply systems it is recommended to choose the automatic starting voltage, as in this case the
starting voltage value is adapted to slow voltage fluctuations.
In the first cycle, a speed jump is issued in v/f-characteristic operation, and in vector controlled operation, the
limit of the speed controller is set to the measured slip so that the drive is put in no-load operation.
To safely decelerate the drive in v/f-characteristic operation, the controller parameters of the active current
controller are lowered to below of the restart value, linearly with the base value.
Restart at power recovery
Only in this mode the system recovery can be constantly detected. An immediate restart upon power recovery
is possible.
After detecting the power recovery the restart delay (Pn.52) runs down and the drive accelerates to the current
setpoint value.
An immediate restart is not executed below the restart value (Pn.48). The drive decelerates with the quick stop
function (Pn.60..61) and behaves according to the adjustment in Pn.44 bit 3...4 or after expiration of Pn.96.
To have more energy available for braking the inertia mass on reaching standstill in v/f-characteristic operation,
the voltage setpoint can be increased to the voltage setpoint (Pn.50) (Pn.44 Bit 6...7 = 2) (if below the restart
level (Pn.48)).
In this case the control remains active with the increased setpoint value. A restart is possible then only after
reaching the standstill.Then the behaviour of Pn.44 Bit 3...4 is defined.
In this mode, too, the lowering of the controller parameter is executed.
© KEB, 2012-10 COMBIVERT F5-A, -E, -H Page 7.13 - 37