ABB RELION 620 Series Technical Manual page 557

1MAC504801-IB E
5.5.5
620 series ANSI
Technical Manual
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, the drop-off timer is activated.
Drop-off timer
Once activated, the drop-off timer remains active until the input is deactivated or at least
during the drop-off time. The BLOCK signal can be used to block the TRIP signal or the
light signal output ARC_FLT_DET.
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 ground-fault current measurement.
The function detects light from an arc either locally or via a remote light signal. Locally,
the light is detected by lens sensors connected to the inputs Light sensor 1, Light sensor
2, or Light sensor 3 on the communication module of the relay. The lens sensors can be
placed, for example, in the busbar compartment, the breaker compartment, and the cable
compartment of the metal-clad cubicle.
The light detected by the lens sensors is compared to an automatically adjusted reference
level. Light sensor 1, Light sensor 2, and Light sensor 3 inputs have their own reference
levels. When the light exceeds the reference level of one of the inputs, the light is detected
locally. When the light has been detected locally or remotely and, depending on the
operation mode, if one or several phase currents exceed the set Phase pickup value limit,
or the ground-fault current the set Ground pickup value limit, the arc protection stage
generates a trip signal. The stage is reset in 30 ms, after all three-phase currents and the
ground-fault current have fallen below the set current limits.
Protection-related functions
Section 5
551