8.4.4 Stopping Servomotor after SV_OFF Command or Alarm Occurrence
The stopping method can be selected after the SV_OFF command is received or an alarm occurs.
• Dynamic braking (DB) is used for emergency stops. The DB circuit will operate fre-
quently if the power is turned ON and OFF or the SV_ON command and SV_OFF
command are received with a reference input applied to start and stop the servomo-
tor, which may result in deterioration of the internal elements in the SERVOPACK.
Use speed input references or position references to start and stop the servomotor.
• Dynamic braking is an auxiliary function for an emergency stop. It is not intended to
stop the motor. The motor may coast to a stop due to a fault. For protection, install
stopping equipment to ensure safety at the machinery if an error occurs.
• Do not use the servo drive with a load moment of inertia that exceeds the allowable
value. Doing so may result in damage or failure of the resistors or power elements in
the SERVOPACK.
• Parameters cannot be used to set the stopping method for the servomotor if the main
circuit power supply (L1, L2, L3) or the control power supply (24 V or 0 V) is turned
OFF during operation without turning OFF the servo. The stopping method depends
on the conditions, as given below.
• Turning OFF the main circuit power supply without turning OFF the servo: The
alarm stopping method is used. For details, refer to 11.2.1 List of Servo Drive
Alarms.
• Turning OFF the control power supply without turning OFF the servo: Refer to the
following table.
• If the servomotor must be stopped by coasting rather than by dynamic braking when
the main circuit power supply or the control power supply is turned OFF but the
SV_OFF command has not been received, arrange the sequence externally so the
current will be cut off for servomotor wires U, V, and W.
• To minimize the coasting distance of the servomotor to come to a stop when an alarm
occurs, the zero-speed stopping method is factory-set for alarms to which the zero-
speed stop method is applicable. The DB stopping method may be more suitable than
the zero-speed stopping method, however, depending on the application.
For example, for multiple axes coupling operation (a twin-drive operation), machinery
damage may result if a zero-speed stop alarm occurs for one of the coupled shafts
and the other shaft stops by dynamic brake. In such cases, change the method to the
DB stopping method.
• If an induction motor is used (Pn01E.0 = 1, 3, or 5), a coasting to a stop is performed
without dynamic braking even if a combination with a DB circuit is specified. If an
induction motor is used, always set Pn001.0 to 2.
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