Basler Electric BE1-11t - Manual (Page 302)

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compensate for the ±30°, ±60°, ±90°, ±120°, ±150°, and ±180° phase shifts that are possible in
transformers and sensing CT configurations.
Mathematically, the compensation factors provide the following:
Note: A 1/(square root of 3) factor is missing from the compensation equations. See Table 99 for the net
compensation equations.
DAB:
b I a I a I
ˆ ˆ
'
ˆ − =
,
c I b I b I
ˆ ˆ
'
ˆ − =
,
a I c I c I
ˆ ˆ
'
ˆ − =
(+30)
DAC:
c I a I a I
ˆ ˆ
'
ˆ − =
,
a I b I b I
ˆ ˆ
'
ˆ − =
,
b I c I c I
ˆ ˆ
'
ˆ − =
(-30)
REV:
a I a I
ˆ
'
ˆ − =
b I b I
ˆ
'
ˆ − =
c I c I
ˆ
'
ˆ − =
(+180)
R1:
c I a I
ˆ
'
ˆ =
,
a I b I
ˆ
'
ˆ =
,
b I c I
ˆ
'
ˆ =
(+120)
R2:
b I a I
ˆ
'
ˆ =
,
c I b I
ˆ
'
ˆ =
,
a I c I
ˆ
'
ˆ =
(+240)
DDAB:
b I a I a I '
ˆ
'
ˆ
"
ˆ − =
,
c I b I b I '
ˆ
'
ˆ
"
ˆ − =
,
a I c I c I '
ˆ
'
ˆ
"
ˆ − =
(0 or +60)
The net effect of DDAB compensation is as follows:
c I b I a I a I ' '
ˆ
2 '
ˆ
"
ˆ + ⋅ − =
c I b I a I b I
ˆ
2
ˆ ˆ
"
ˆ ⋅ − + =
c I b I a I c I
ˆ ˆ ˆ
2 "
ˆ + + ⋅ − =
WYE:
a I a I
ˆ
'
ˆ =
,
b I b I
ˆ
'
ˆ =
,
c I c I
ˆ
'
ˆ =
(no compensation)
The following tables illustrate how the various phase compensation factors are applied to different winding
and CT configurations.
The BE1-11t can also compensate for phase “mismatch”. That is, if A phase of the incoming system is
connected to the transformer primary H1 and A phase of the secondary system is connected to X2, the
phases can be matched at the BE1-11t with this feature. Phase matching can be set through
BESTCOMSPlus on the System Parameters, Transformer Setup screen.
Settings for the current measurement functions are provided in the following tables. These tables indicate
the transformer circuit, CT settings, and type of phase compensation applied for various transformer
applications. The settings are indicated on a per circuit basis. A circuit consists of one of the transformer’s
three-phase windings and its corresponding set of three-phase CT’s.
Table 96 and Table 97 are applied when a combination of delta and wye connections are present in the
transformer and CT circuits. Table 96 is applied when only one type of delta connection is present in the
transformer and CT circuits, such as DAB or DAC. This table is used for the majority of applications. If the
application requires a combination of delta circuits, such as both DAB and DAC connections being
present, Table 97 is applied. The only exceptions are when all CT and winding connections are wye as
indicated above. Or, when one or more of the individual transformer windings are connected in delta or
zigzag and has its corresponding CTs connected in delta. Table 98 is applied when one or more of the
individual transformer windings is connected in delta or zigzag and has its corresponding CTs connected
in delta. The special connection can require up to two delta compensations for the other windings
depending on the circuit’s configuration.
Configuration BE1-11t