moog
MSD Servo Drive Compact Operation Manual
32
Id no.: CA97555-001, Rev. 3.0 - Date: 06/2012
3.13.3 Switching in the motor cable
ATTENTION!
Switching in the motor cable must take place with the power
cut and the power stage disabled, as otherwise problems such as burned-off
contactor contacts may occur. In order to ensure unpowered switch-on, you
must make sure that the contacts of the motor contactor are closed before
the drive power stage is enabled. At the moment the contactor is switched
off it is necessary for the contact to remain closed until the drive power stage
is shut down and the motor current is 0. This is done by inserting appropriate
safety times for switching of the motor contactor in the control sequence of
your machine.
Despite these measures, the possibility cannot be ruled out that the drive may
malfunction during switching in the motor cable.
!
3.14 Braking resistor (RB)
In regenerative operation, e.g. when braking the drive, the motor feeds energy back to
the drive. This increases the voltage in the DC link. If the voltage exceeds a threshold
value, the internal braking transistor is activated and the regenerated power is converted
into heat by means of a braking resistor.
3.14.1 Protection in case of braking chopper fault
ATTENTION!
If the internal braking chopper transistor is permanently
switched on, because it is alloyed through by overload (= 0
Ω
), there is a
protective function to protect the device against overheating.
You activate this function by assigning to any digital output (Moog
D
rive
A
DministrAtor
5
►
expert field "I/O configuration"
►
digital outputs
►
OSD00 to OSD02) with
BC_FAIL(56)
. In the event of a fault the selected
output then switches from 24 V to 0 V. This signal ensures that the drive is
safely disconnected from the mains supply.
For detailed information on parameterization refer to the MSD Servo Drive application
manual.
3.14.2 Design with integrated braking resistor (C3 + C4)
The Ordering Catalog only specifies the peak braking power for the servo drives with
integrated braking resistor (model G394-xxx-xxx-xx2). The permissible continuous
braking power must be calculated. It depends on the effective loading of the drive in the
corresponding application.
The drive is thermally designed in such a way that no energy input by the internal
braking resistor is permitted during continuous operation with rated current and at
maximum ambient temperature.
Consequently, a drive design featuring an integrated braking resistor only makes sense
when the effective drive load is ≤80% or the braking resistor is designed for one-off
emergency stop. In the event of an emergency stop, only the heat capacity of the
braking resistor can be used for a one-off braking action. The permissible energy W
IBr
can be taken from the following table.
!
