January 2011
5 of 9
Impulse•G+/VG+ Series
3
Safe-Off 8001.x
PN:
140-10305
Introduction to Safe-Off
The Safe-Off option, when used with other safety components, provides protection according to
EN954-1 Category 3
for safe stop and protection against restart. An Impulse•G+/VG+ Series 3
drive equipped with the Safe-Off option is just one component in a safety control system. To
ensure that the Safe-Off function appropriately fulfills the safety requirements of the application,
a thorough risk assessment shall be done according to
ISO12100
for the whole safety system at
the final installation. All components in the system must be appropriately selected and applied to
achieve the desired safeguarding.
The Safe-Off function performs a safe stop according to
EN60204-1 Stop Category 0
referred
to as “uncontrolled stop by power removal” or “coast to stop.” Safe-Off is certified to meet the
requirements of
EN954-1, Safety Category 3
. The Safe-Off function is implemented totally in
hardware on the Impulse•G+/VG+ Series 3 control and interface board.
Safe-Off disables the motor, not the drive controller. Power to the control board and display is
maintained so all parameters, monitors and fault data may be read and observed. Also, all
communications stay active.
The Safe-Off function uses two independent hardware channels to redundantly block the driver
signals to the output devices (IGBTs) so the motor is disabled and operation prevented.
Redundancy ensures that a single fault in any of the parts involved in Safe-Off does not lead to
a loss of the safety function.
Safe-Off is completely electronic; no mechanical moving parts (relays) are involved in the Safe-
Off circuitry. Safe-Off is suitable in applications classified as “medium risk” where coasting to a
stop is the appropriate response to a fault condition.
Safe-Off prevents the motor from moving; the Safe-Off option does
not
serve as a motor
disconnecting means (NEC Article 430 Part IX) and does
not
provide electrical shock safety. It
is only suitable for preventing motor operation when people are working near parts of a machine
affected by the drive system.
The Safe-Off option should
not
be used as the normal means to start and stop the drive.
NOTE
: The Safe-Off interface board is ONLY available in 24 VDC
.
