50 Unidrive M / HS Frame 7 to 10 Power Installation Guide
Issue Number: 5
4 Electrical installation
Electric shock risk
The voltages present in the following locations can cause severe electric shock and may be
lethal:
AC supply cables and connections
DC and brake cables, and connections
Output cables and connections
Many internal parts of the drive, and external option units
Unless otherwise indicated, control terminals are single insulated and must not be touched.
Isolation device
The AC and / or DC power supply must be disconnected from the drive using an approved
isolation device before any cover is removed from the drive or before any servicing work
is performed.
STOP function
The STOP function does not remove dangerous voltages from the drive, the motor or any
external option units.
Safe Torque Off function
The Safe Torque Off function does not remove dangerous voltages from the drive, the
motor or any external option units.
Stored charge
The drive contains capacitors that remain charged to a potentially lethal voltage after the
AC and / or DC power supply has been disconnected. If the drive has been energized,
the AC and / or DC power supply must be isolated at least ten minutes before work may
continue. Normally, the capacitors are discharged by an internal resistor. Under certain,
unusual fault conditions, it is possible that the capacitors may fail to discharge, or be
prevented from being discharged by a voltage applied to the output terminals. If the drive
has failed in a manner that causes the display to go blank immediately, it is possible the
capacitors will not be discharged. In this case, consult Emerson Industrial Automation or
their authorized distributor.
Equipment supplied by plug and socket
Special attention must be given if the drive is installed in equipment which is connected to
the AC supply by a plug and socket. The AC supply terminals of the drive are connected
to the internal capacitors through rectifier diodes which are not intended to give safety
isolation. If the plug terminals can be touched when the plug is disconnected from the
socket, a means of automatically isolating the plug from the drive must be used (e.g. a
latching relay).
Permanent magnet motors
Permanent magnet motors generate electrical power if they are rotated, even when the
supply to the drive is disconnected. If that happens then the drive will become energized
through its motor terminals. If the motor load is capable of rotating the motor when the
supply is disconnected, then the motor must be isolated from the drive before gaining
access to any live parts.
Unidrive M frame7 to 10 Power Installation Guide issue5.book Page 50 Tuesday, May 24, 2016 11:52 AM
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