Arc Protection Relay
REA 10_
1MRS750929-MBG
5
.
The information in the table 1 is based on the
following reference conditions:
• Copper busbars
• Arc length 10 cm
• Surrounding light ~ 400 lux
• No reflecting surfaces
• Light reference level is set one scale mark
to the right from the minimum
Sensitivity of lens sensors
The relative sensitivity of the lens sensor
from different angles of lightning is presented
in figure 2. The normal operating sector is -
130°... +130°. In practice, light is also
reflected from the compartment walls, so the
detecting angle is not critical.
The detection distance of a lens sensor is 3
meters. Therefore, when protecting busbar
sections, the maximum distance of lens sen-
sors from one another is 6 meters
.
SensitivityAngles
Fig. 2
Relative sensitivity of the REA lens sensor
from different angles of lighting
Trip output
The trip output is provided with:
• Two high-speed galvanically isolated
IGBT semi-conductor outputs, HSO1 and
HSO2
• Relay output, TRIP3
The control signal of the outputs is activated
if the overcurrent signal and the light signal,
but not the operating voltage fault signal, are
active at the same time.
When the “Trip Condition” key switch on the
relay’s front panel is in “Light” position, the
overcurrent signal is constantly active, and
tripping is activated by an arc alone. When a
trip signal is delivered, the trip outputs are
latched in active state. The outputs can be
reseted either by pushing the “Reset” button
on the relay’s front panel, or by using a reset
signal applied to RESET input.
Ports A and B for connecting extension
units
The selection switches are used to activate the
ports A and B.
The extension units are connected to the ports
A and B by using connection cables. The
extension unit receives its operating voltage
and operation signals over the port.
The ports are protected against short-circuit
and cable breaks. If the connection cable
from a port breaks, the concerned chain is
disconnected, and the fault LED (Port A
Fault” or “Port B Fault”) as well as the “IRF”
LED on the central unit are lit, and the IRF
relay resets.
A maximum of 5 extension units can be con-
nected to one port. If an extension unit
included in the chain connected to the port is
damaged, the fault LED of the port starts
flashing, the “IRF” LED is lit and the IRF
relay resets.
Table 1: Minimum length (cm) of the exposed sensor fiber per one switchgear
compartment
Fault current (rms)
Distance between sensor and arc
100 cm
200 cm
300 cm
400 cm
0.5 kA
20
-
a
-
a
-
a
0.7 kA
20
70
210
280
1.4 kA
20
20
20
140
2.2 kA
20
20
20
20
a) Not operational.
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