14   Safety instructions
Permanent magnet motor
These are additional warnings for permanent magnet motor drives. If you ignore the 
instructions, physical injury or death, or damage to the equipment can occur. 
Control a permanent magnet motor only with the ACS800 Permanent Magnet 
Synchronous Motor Drive Control Program.
 Installation and maintenance work
WARNING! Do not do work on the drive when the permanent magnet motor 
turns. When the supply power is off and the inverter is stopped, a turning 
permanent magnet motor feeds power to the intermediate circuit of the 
drive and the supply connections become live.
Before you do installation and maintenance work on the drive:
• Stop the motor.
• Make sure that the motor cannot turn during work. Prevent the start-up of any 
drives in the same group by opening the Prevention of unexpected start switch 
(option +Q950) or the Safe torque off switch (option +Q967) and locking it. Make 
sure that no other system, such as hydraulic crawling drives, are able to turn the 
motor directly or through any mechanical connection such as felt, nip, rope, and 
so on.
• Make sure that there is no voltage on the drive power terminals:
Alternative 1)
 Disconnect the motor from the drive with a safety switch or by 
other means. Measure that there is no voltage present on the drive input, output 
or DC terminals (U1, V1, W1, U2, V2, W2, UDC+, UDC-).
Alternative 2) 
Measure that there is no voltage present on the drive input, output 
or DC terminals (U1, V1, W1, U2, V2, W2, UDC+, UDC-). Ground the drive output 
terminals temporarily by connecting them together and to the PE.
Alternative 3) 
If it is possible, do both of the above
.
 Start-up and operation 
WARNING! Do not run the motor over the rated speed. Motor overspeed 
leads to overvoltage which can damage the capacitors in the intermediate 
circuit of the drive.