ABB ACS550-02 User Manual page 25

IT (ungrounded) Systems
The ACS550 drive is suitable for IT (ungrounded systems). Disconnect the filter
before connecting the drive to an ungrounded system. For detailed instructions on
how to do this, please contact your local ABB representative.
WARNING! If a drive is installed on an IT system [an ungrounded power system or a
high resistance-grounded (over 30 ohms) power system], the system will be
connected to earth potential through the EMC filter capacitors of the drive. This may
cause danger or damage the unit.
Required Tools
• 3 mm (0.12 in) screw driver
• 10 mm (3/8 in) Torx screw driver
• torque wrench with 500 mm (20 in) or 2 x 250 mm (2 x 10 in) extension bar
• 19 mm (3/4 in) socket
for frame size R7: 13 mm (1/2 in) magnetic end socket
for frame size R8: 17 mm (11/16 in) magnetic end socket.
Checking the Insulation of the Assembly
Every drive has been tested for insulation between the main circuit and the chassis
(2500 V rms 50 Hz for 1 second) at the factory. Therefore, do not make any voltage
tolerance or insulation resistance tests (e.g. hi-pot or megger) on any part of the
drive. When checking the insulation of the assembly, proceed in the following
manner:
WARNING! Check the insulation before connecting the drive to the mains. Make
sure that the drive is disconnected from the mains (input power).
1. Check that the motor cable is disconnected from the drive output terminals U2,
V2 and W2.
2. Measure the insulation resistance of the motor cable and the motor between each
phase and the Protective Earth by using a measuring voltage of 1 kV DC. The
insulation resistance must be higher than 1 Mohm.
ohm
M
PE
23
Installation