Vacon 100 - Page 310

P3.20.2 BRAKE MECHANICAL DELAY (ID 353)
After the brake opening command is given, the speed stays at the value of the parameter
P3.20.3 (Brake Opening Frequency Limit) until the brake mechanical delay is expired. Set the
delay time to agree with the reaction time of the mechanical brake.
The Brake mechanical delay function is used to prevent current and/or torque spikes. This
prevents the motor from operating at full speed against the brake. If you use P3.20.2 at the
same time with P3.20.8, it is necessary to have the expired delay and the feedback signal to
release the speed reference.
P3.20.3 BRAKE OPENING FREQUENCY LIMIT (ID 1535)
The value of the parameter P3.20.3 is the output frequency limit of the drive to open the
mechanical brake. In open loop control, we recommend that you use a value that is equal to
the nominal slip of the motor.
The output frequency of the drive stays at this level until the brake mechanical delay is
expired, and the system receives the correct brake feedback signal.
P3.20.4 BRAKE CLOSING FREQUENCY LIMIT (ID 1539)
The value of the parameter P3.20.3 is the output frequency limit of the drive to close the
mechanical brake. The drive stops and the output frequency goes near 0. You can use the
parameter for the 2 directions, positive and negative.
P3.20.5 BRAKE CURRENT LIMIT (ID 1085)
The Mechanical brake closes immediately if the motor current is below the limit set in
parameter Brake Current Limit. We recommend that you set the value to approximately half
of the magnetisation current.
When the drive operates on the field weakening area, the brake current limit decreases
automatically as a function of output frequency.
ID1085
ID602
Brake
current limit
Current (A)
Output
frequency (Hz)
Field weakening point
Field weakening area
Fig. 89: Internal reduction of the brake current limit
VACON · 310 PARAMETER DESCRIPTIONS
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