Ground Fault Protection; Prevention Of Unexpected Start - ABB ACS800 Hardware Manual

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Ground fault protection

The drive is equipped with an internal ground fault protective function to protect the
unit against ground faults in the motor and motor cable. This is not a personal safety
or a fire protection feature. The ground fault protective function can be disabled with
a parameter, refer to the appropriate ACS800 Firmware Manual.
The EMC filter of the drive includes capacitors connected between the main circuit
and the frame. These capacitors and long motor cables increase the ground leakage
current and may cause fault current circuit breakers to function.

Prevention of Unexpected Start

The drive can be equipped with an optional Prevention of Unexpected Start function
according to standards IEC/EN 60204-1: 1997; ISO/DIS 14118: 2000 and EN 1037:
1996.
The Prevention of Unexpected Start function disables the control voltage of the
power semiconductors, thus preventing the inverter 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 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.
• safety relay (type BD5935 has been approved by ABB)
For connections to the drive, see chapter Installation of AGPS board (Prevention of
Unexpedted Start, +Q950).
WARNING! The Prevention of Unexpected Start 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: If a running drive is stopped by using the Prevention of Unexpected Start
function, the drive will cut off the motor supply voltage and the motor will coast to
stop.
Planning the electrical installation