Application - ABB RELION REX640 Technical Manual

Section 4
Protection functions
4.9.6
986
input is activated, the operation of the function is based on light information only.
When the OPR_MODE input is deactivated, the operation of the function is based on
both light and current information. When the required criteria are met, Fixed delay 1
timer is activated.
Fixed delay 1
Once this timer is activated, the OPERATE signal output is activated immediately. The
output is kept active for minimum 25 ms or as long as the input is activated. The
BLOCK signal can be used to block the OPERATE signal.
Fixed delay 2
Once this timer is activated, the ARC_FLT_DET output is activated immediately. The
output is kept active for minimum 25 ms or as long as the input is activated. The
BLOCK signal can be used to block the ARC light signal output ARC_FLT_DET.
Supervision
If a faulty arc sensor is internally detected or if the connection to the arc sensor is lost,
ALARM output is activated if Sensor supervision is set to "on".
When Sensor supervision is set to "off", ALARM output stays false even though the arc
sensor is faulty or unconnected.

Application

The arc protection can be realized as a stand-alone function in a single relay or as a
station-wide arc protection, including several protection relays. If realized as a
station-wide arc protection, different tripping schemes can be selected for the
operation of the circuit breakers of the incoming and outgoing feeders. Consequently,
the relays in the station can, for example, be set to trip the circuit breaker of either the
incoming or the outgoing feeder, depending on the fault location in the switchgear. For
maximum safety, the relays can be set to always trip both the circuit breaker of the
incoming feeder and that of the outgoing feeder.
The arc protection consists of:
• Optional arc light detection hardware with automatic backlight compensation for
lens type sensors
• Light signal output ARC_FLT_DET for routing indication of locally detected
light signal to another relay
• Protection stage with phase- and earth-fault current measurement.
The function detects light from an arc either locally or via a remote light signal.
Locally, the light is captured either by lens type point sensors or transparent fiber loop
sensors connected to the light sensor input of the relay. This captured light is guided
via optical fiber to the sensor input of the relay, where it is converted to electrical
signal by means of a photo diode. The optical light sensors can be placed in the various
1MRS759142 C
REX640
Technical Manual