ABB ret650, Руководство по применению, Страница: 226 / 392

• Over-Current
• Total block via settings
• Total block via configuration
• Analog input error
• Automatic block via settings
• Automatic block via configuration
• Under-Voltage
• Command error
• Position indication error
• Tap changer error
• Reversed Action
• Circulating current
• Communication error
Master-follower method
When the master is blocked, the followers will not tap by themselves and there is
consequently no need for further mutual blocking. On the other hand, when a
follower is blocked there is a need to send a mutual blocking signal to the master.
This will prevent a situation where the rest of the group otherwise would be able to
tap away from the blocked individual, and that way cause high circulating currents.
Thus, when a follower is blocked, it broadcasts a mutual block on the horizontal
communication. The master picks up this message, and blocks its automatic
operation as well.
Besides the conditions listed above for mutual blocking with the circulating current
method, the following blocking conditions in any of the followers will also cause
mutual blocking:
• Master-follower out of position
• Master-follower error (No master/More than one master)
General
It should be noted that partial blocking will not cause mutual blocking.
TR8ATCC, which is the “source” of the mutual blocking will set its AUTOBLK
output as well as the output which corresponds to the actual blocking condition for
example, IBLK for over-current blocking. The other TR8ATCCs that receive a
mutual block signal will only set its AUTOBLK output.
The mutual blocking remains until TR8ATCC that dispatched the mutual block
signal is de-blocked. Another way to release the mutual blocking is to force
TR8ATCC, which caused mutual blocking to Single mode operation. This is done
by activating the binary input SNGLMODE on TR8ATCC function block or by
setting the parameter
OperationPAR to Off from the built-in local HMI or PST.
TR8ATCC function can be forced to single mode at any time. It will then behave
exactly the same way as described in section
"Automatic voltage control for a
Section 11
1MRK 504 169-UEN A
Control
220 Transformer protection RET650 2.2 IEC
Application manual