11. Trip-circuit supervision
The trip-circuit supervision continuously monitors
the availability and operability of the trip circuit. It
provides open-circuit monitoring both when the cir-
cuit breaker is in its closed and in its open position.
It also detects loss of circuit-breaker control voltage.
12. Access control
To protect the relay from unauthorized access and
to maintain the integrity of information, the relay
is armed with a three level, role-based user au-
thentication system with individual password for
the operator, engineer and administrator level. The
password is a combination of different navigation
keys.
13. Inputs and outputs
The relay is equipped with three Rogowski sensor
inputs. The relay has an additional earth-current
input suitable for a 1A which can be connected to
core-balanced current transformer /split core cur-
rent transformer.
Relay binary input/output overview:
• Two binary inputs one for remote-trip and one for
remote-reset
• One normally open trip output, with trip circuit
supervision functionality
• One normally-closed trip output
• Two signalling outputs one for phased over-
current fault and one for earth fault
• One breaker close output
• Unit ready / IRF output
• LED indication for Ready/IRF, Protection start,
protection trip, Phase fault and Earth fault trip,
Trip circuit fault
14. Communication
The relay is available with optional communica-
tion feature with Modbus RTU protocol on RS-485
bus with two wire connection. This allows relay to
connect to control and monitoring system through
serial communication for remote monitoring.
15. Application warning
In case the relay REF601 is supplied with UPS step-
wave or square-wave, an interposing transformer is
needed to keep the supply voltage (peak voltage)
below the upper limit of the relay.
These are the recommended transformer charac-
teristics:
• Nominal Power: 20 VA
• Secondary voltage: in the range 30...150 V AC
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