Nidec D3-0023-B, Руководство пользователя

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54
Digistart D3: User Guide
Issue: G
7.3.4 Brake
Brake reduces the time required to stop the motor.
During braking an increased noise level from the motor may be audible. This is a normal part of motor braking.
When brake is selected, the Digistart D3 uses DC injection to slow the motor.
Digistart D3 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.
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.
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 (Pr 6G).
Braking has two stages:
• Pre-brake: provides an intermediate level of braking to slow motor speed to a point where full brake can be
operated successfully (approximately 70% speed).
• Full brake: brake provides maximum braking torque but is ineffective at speeds greater than approximately
70%.
To configure the Digistart D3 for brake operation:
1. Set Pr 2I for the desired stopping time duration (1). This is the total braking time and must be set sufficiently
longer than the brake time (Pr 2N) 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 Brake Time (Pr 2N) to approximately one quarter of the programmed Stop Time. This sets the time for the
Full Brake stage (2).
3. Adjust the Brake Torque (Pr 2M) 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.
S
peed
100%
75%
0%
50%
25%
1
2
3
1: Stop Time (Pr 2I)
2: Brake Time (Pr 2N)
3: Coast to stop time
Time
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 Pr 5D 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 Digistart D3 with an external speed sensor (eg for applications with
variable load during the braking cycle), see DC Brake with External Zero Speed Sensor on page 102.