Planning the electrical installation
48
Prevention of unexpected start-up (option +Q950)
The drive can be equipped with an optional Prevention of unexpected start-up
function according to standards:
• IEC/EN 60204-1:1997,
• ISO/DIS 14118:2000,
• EN 1037:1996,
• EN ISO 12100:2003,
• EN 954-1:1996,
• EN ISO 13849-2:2003.
The Prevention of unexpected start-up (POUS) function disables the control voltage
of the power semiconductors, thus preventing the drive from generating the AC
voltage required to rotate the motor. By using this function, short-time operations
(like cleaning) and/or maintenance work on non-electrical parts of the machinery can
be performed without switching off the AC power supply to the drive.
The operator activates the Prevention of unexpected start-up function by opening a
switch on a control desk. An indicating lamp on the control desk will light, signalling
that the prevention is active. The switch can be locked out.
The user must install on a control desk near the machinery:
• switching/disconnecting device for the circuitry. “Means shall be provided to
prevent inadvertent, and/or mistaken closure of the disconnecting device.”
EN 60204-1:1997.
• indicating lamp; on = starting the drive is prevented, off = drive is operative.
For connections to the drive, see the circuit diagram delivered with the drive.
WARNING! The Prevention of unexpected start-up function does not disconnect the
voltage of the main and auxiliary circuits from the drive. Therefore maintenance work
on electrical parts of the drive or the motor can only be carried out after isolating the
drive system from the main supply.
Note: The Prevention of unexpected start-up function is not intended for stopping
the drive. If the Prevention of unexpected start-up function is activated when the
drive is running, the control voltage of the power semiconductors is cut off and the
motor coasts to a stop.
For detailed instructions for installation, start-up, use and maintenance of the
function, see chapter Installation of the AGPS board (Prevention of unexpected
start-up, +Q950).
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