ABB REG670 Applications Manual page 564

Section 15
Control
558
Selecting a master is made by activating the input FORCMAST in TR8ATCC
function block. Deselecting a master is made by activating the input RSTMAST.
These two inputs are pulse activated, and the most recent activation is valid that is, an
activation of any of these two inputs overrides previous activations. If none of these
inputs has been activated, the default is that the transformer acts as a follower (given
of course that the settings are parallel control with the master follower method).
When the selection of master or follower in parallel control, or automatic control in
single mode, is made with a three position switch in the substation, an arrangement as
in figure 285 below is arranged with application configuration.
M
F
I
IEC06000633 V2 EN
Figure 285: Principle for a three-position switch Master/Follower/Single
Parallel control with the reverse reactance method
Consider Figure 286 with two parallel transformers with equal rated data and similar
tap changers. The tap positions will diverge and finally end up in a runaway tap
situation if no measures to avoid this are taken.
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
1MRK 502 071-UEN -
BIM/IOM TR8ATCC
FORCMAST
RSTMAST
SNGLMODE
IEC06000633-2-en.vsd
Application manual