MCD 500 braking
•
Does not require the use of a DC brake contactor
•
Controls all three phases so that the braking
currents and associated heating are evenly
distributed through the motor
Braking has two stages
1.
Pre-brake: provides an intermediate level of
braking to slow motor speed to a point where
full brake can be operated successfully (approxi-
mately 70% speed).
2.
Full brake: brake provides maximum braking
torque but is ineffective at speeds greater than
approximately 70%.
To configure the MCD 500 for brake operation
1.
Set
1-11 Stop Time
for the desired stopping time
duration (1). This is the total braking time and
must be set sufficiently longer than the brake
time (
1-16 Brake Time
) to allow the pre-braking
stage to reduce motor speed to approximately
70%. If the stop time is too short, braking will not
be successful and the motor will coast to stop.
2.
Set
1-16 Brake Time
to approximately one quarter
of the programmed Stop Time. This sets the time
for the Full Brake stage (2).
3.
Adjust
1-15 Brake Torque
so that the desired
stopping performance is achieved. If set too low,
the motor will not stop completely and will coast
to stop by the end of the braking period.
100%
70%
0%
30%
1
2
3
177HA511.10
Time
S
p
ee
d
Illustration 5.8
1:
1-11 Stop Time
2:
1-16 Brake Time
3: Coast to stop time
Table 5.6
NOTE
When using DC brake, the mains supply must be
connected to the soft starter (input terminals L1, L2, L3) in
positive phase sequence and
2-1 Phase Sequence
must be
set to Positive only.
NOTE
For loads which may vary between braking cycles, install a
zero speed sensor to ensure that the soft starter ends DC
braking when the motor stops. This avoids unnecessary
heating of the motor.
For more information on using the MCD 500 with an
external speed sensor, see
5.12 DC Brake with External Zero
.
5.5 Jog Operation
Jog runs the motor at reduced speed, to allow alignment
of the load or to assist servicing. The motor can be jogged
in either forward or reverse direction.
The maximum available torque for jog is approximately
50% - 75% of motor full load torque (FLT) depending on
the motor. Available jog torque in reverse is approximately
50% - 75% of the jog torque in forward direction. To set
the jog torque level, use
15-8 Jog Torque
.
NOTE
Setting
15-8 Jog Torque
above 50% may cause increased
shaft vibration.
Application Examples
MCD 500 Operating Instruction
34
MG17K402 - VLT
®
is a registered Danfoss trademark
5
5