APPLICATION EXAMPLES
11.5
DC Brake with External Zero Speed Sensor
For loads which may vary between braking cycles, there are benefits in using an external zero-speed sensor to interface with the
EMX3 for brake shut-off. This control method ensures that the EMX3 braking will always shut off when the motor has reached a
standstill, thus avoiding unnecessary motor heating.
The following schematic diagram shows how you can use a zero-speed sensor with the EMX3 to turn the brake function off at motor
standstill. The zero-speed sensor (A2) is often referred to as an under-speed detector. Its internal contact is open at zero-speed
and closed at any speed above zero-speed. Once the motor has reached a standstill, C53, C54 will open and the starter will be
disabled. When the next start command is given (ie next application of K10), C53, C54 closes and the EMX3 is enabled.
The EMX3 must be operated in remote mode and parameter 6A
Input A Function
must be set to 'Starter Disable'.
CAUTION
Brake operation causes the motor to heat faster than the rate calculated by the motor thermal model. If you are using
brake, install a motor thermistor or allow sufficient restart delay (parameter 4M).
-F1
L3
L2
L1
N
E
-K10
L1
L2
L3
E
T1
T2 T3
A2
A3
A1
C23 C24
C31 C32
C41 C42
C53 C54
-K10
-K11
-K10
-K11
T3
T2
T1
M
3
-K11
-K10
-A2
06401.
E
1
Control voltage
A
Off (Ready)
C23, C24 Start
B
Start
C31, C32 Stop
C
Run
C41, C42 Reset
D
Stop
C53, C54
Programmable input A (Starter Disable)
E
Zero speed
2
Motor terminals
5
Start signal
3
Three-phase supply
6
Zero speed sensor
4
Starter Disable (shown on starter display)
For details on configuring DC Brake, refer to
Brake
on page 36.
CAUTION
When using DC brake, the mains supply must be connected to the soft starter (input terminals L1, L2, L3) in positive
phase sequence and parameter 4G
Phase Sequence
must be set to Positive Only.
CAUTION
If the brake torque is set too high, the motor will stop before the end of the brake time and the motor will suffer
unnecessary heating which could result in damage. Careful configuration is required to ensure safe operation of the
starter and motor.
A high brake torque setting can result in peak currents up to motor DOL being drawn while the motor is stopping.
Ensure protection fuses installed in the motor branch circuit are selected appropriately.
66
| User Manual (710-04840-00M)
