ABB REU 610 Technical Reference Manual page 88

REU 610
88
Voltage Relay
Technical Reference Manual - ANSI Version
and the link is busy, the relay first waits until the link becomes idle. After this,
a backoff time starts. When the backoff time elapses, the relay checks the link
again. If the link is not busy, the relay starts 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 is 100
milliseconds.
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, the relay supervises collisions on
the link. If a collision is detected, the transmission is immediately cancelled.
After this, the relay tries to transmit the message again, using collision
avoidance before sending the message.
Scaling DNP analog values
The DNP analog values can be scaled using either an internal (fixed) or a
user-defined scaling factor. If the scaling factor index for a certain analog
value is set to 0, the internal scaling factor is used. If set to 1...5, the user-
defined scaling factor of the corresponding scaling factor parameter, SPA
parameter 503V (100+index), is used:
Scaling factor 1
503V101
Scaling factor 2
503V102
Scaling factor 3
503V103
Scaling factor 4
503V104
Scaling factor 5
503V105
Example:
Phase-to-phase voltage U
Internal scaling factor
Default DNP range
0...2 × U (VT)
ab n
100
0...200
1MRS755972