Planning the electrical installation
87
Implementing a safety switch between the drive and motor
It is recommended to install a safety switch between the permanent magnet
synchronous motor and the drive output. The switch is needed to isolate the motor
during any maintenance work on the drive.
Using a contactor between the drive and motor
Implementing the control of an output contactor depends on how you select the drive
to operate. See also section Implementing a bypass connection on page 88.
When you have selected to use
• DTC or vector motor control mode, and motor ramp stop,
open the contactor as follows:
1. Give a stop command to the drive.
2. Wait until the drive decelerates the motor to zero speed.
3. Open the contactor.
When you have selected to use
• DTC or vector motor control mode, and motor coast stop, or
• scalar control mode,
open the contactor as follows:
1. Give a stop command to the drive.
2. Open the contactor.
WARNING! When the DTC or vector motor control mode is in use, never open the
output contactor while the drive controls the motor. The DTC and vector motor
control operate extremely fast, much faster than it takes for the contactor to open its
contacts. When the contactor starts opening while the drive controls the motor, the
DTC or vector control will try to maintain the load current by immediately increasing
the drive output voltage to the maximum. This will damage, or even burn the
contactor completely.
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