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1MRS 755310
Feeder Protection Relay
Technical Reference Manual
Collision avoidance and detection
REF 610 supports both collision avoidance and detection. Collision detection can be
enabled or disabled with SPA parameter 503V235.
Collision avoidance occurs before message transmission. When preparing to
transmit and the link is busy, REF 610 will first wait until the link becomes idle.
After this, a backoff time will start. When the backoff time elapses, REF 610 will
check the link again. If not busy, REF 610 will start the transmission. The backoff
time is calculated as follows:
backoff time = silent interval + random delay
The silent interval is set with SPA parameter 503V232 and the maximum random
delay with SPA parameters 503V233 (the width of a single time slot in milliseconds)
and 503V234 (the maximum number of time slots). By setting the time-slot width to
10 milliseconds and the maximum number of time slots to 10, for instance, the
maximum random delay will be 100 milliseconds.
Note!
In a network consisting of several slaves, the priority between the devices are
defined with SPA parameters 503V233 and 503V234. A device with shorter silent
interval and maximum random delay has higher sending priority than a device with
longer silent interval and maximum random delay.
Collision detection is always active during transmission (provided that it has been
enabled). While sending a message, REF 610 supervises collisions on the link. If a
collision is detected, the transmission will be immediately cancelled. After this, REF
610 will try to transmit the message again, using collision avoidance before sending
the message.
Scaling DNP analogue values
The DNP analogue values can be scaled using either an internal (fixed) or a
user-defined scaling factor. If the scaling factor index for a certain analogue value is
set to 0, the internal scaling factor will be used. If set to 1...5, the user-defined scaling
factor of the corresponding scaling factor parameter, SPA parameter
503V(100+index), will be used:
503V101
503V102
503V103
503V104
503V105
Example
Phase current I
L1
Internal scaling factor
Default DNP range
Scaling factor 1
Scaling factor 2
Scaling factor 3
Scaling factor 4
Scaling factor 5
0.00...50.0 x I
n
100
0...5000
REF 610
101
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