Lenze E82xVxxxKxxxxx - Manual (Page 278)

Function library
Behaviour in the event of mains switching, mains failure or controller inhibit
Controlled deceleration after mains failure/mains disconnection
10
l
278 EDS82EV903 EN 3.0
10.4.3 Controlled deceleration after mains failure/mains disconnection
Description
)
Note!
ƒ The function described below can be used for max. 1.5 kW rated controller
power. If this function is to be used for greater controller powers, Lenze
must be consulted first.
ƒ The deceleration time until standstill cannot be defined exactly. It depends
on the machine/system components (mass inertia, friction, ...).
Controlled deceleration of the motor to a standstill (f = 0) in case of mains switch−off or
mains failure.
The function can be implemented with or without external brake resistor:
This function serves to prevent the drive from coasting in case of an emergency switching
off (controller is activated via mains).
Without external brake resistor
ƒ Controlled deceleration of the motor to a standstill (f = 0) if the controller is active.
ƒ The braking energy stems from the system losses (controller and motor).
With external brake resistor
ƒ Automatic, quick deceleration of the motor to a standstill (f = 0).
ƒ The deceleration time is shorter than it is without external brake resistor.
Functional sequence
1. The mains voltage is interrupted.
2. The DC−bus voltage (V
DC
) falls below the value in C0988
Þ the controller switches
over to parameter set 1.
3. The drive brakes along the quick stop ramp (C0105 in parameter set 1).
4. Due to operation in generator mode, V
DC
exceeds the value in C0988 Þ the
controller switches over to parameter set 2.
5. The motor accelerates along the acceleration ramp (C0012 in parameter set 2).
6. If the DC−bus voltage falls below the value in C0988 again, the process starts all over
again with step 2.
Steps 2. to 6. are carried out until a motor speed of approx. zero is reached because the
rotational energy in the motor conserves V
DC
.
If the motor is not at a standstill at the time when the mains recovers, the drive will
accelerate to the selected setpoint along the acceleration ramp (C0012). The drive will then
start immediately which results in a rough restart, compared to the flying restart circuit.