Schweitzer Engineering SEL-387-0, Instruction Manual

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H.3
Date Code 20170601 Instruction Manual SEL-387-0, -5, -6 Relay
Protection Application Examples
Transformer Winding and CT Connection Compensation Settings Examples
Figure H.1 Transformer Nameplate
Note that there is no phase designation nor any phase rotation designation on
the nameplate. However, the phasor diagram is representative of an H1-H2-H3
sequence. The phase shift on the power system depends on the transformer
winding connections, the system phase-to-transformer bushing connections,
and the system phase rotation.
Figure H.2 shows a three line connection diagram with the transformer shown
in Figure H.1 with what this guideline refers to as standard connections.
Standard phase-to-bushing connections are A-phase to H1, B-phase to H2,
C-phase to H3, a-phase to X1, b-phase to X2, and c-phase to X3. Standard CT
connections include wye-connected CTs with polarity marks of both CTs
away from or towards the transformer.
Figure H.2 shows both H-side and
X-side CTs connected in wye and the polarity marks away from the
transformer. A CT-to-relay connection is considered to be standard when the
polarity of the CT is connected to the polarity of the relay analog current input
and the primary system phase current is connected to the same phase input on
the relay (e.g., IA system to IAW1). Unless otherwise noted, an ABC phase
rotation is assumed for the following discussion.
KVA. . . . .
HV. . . . .
kV BIL.
LV. . . . .
LV AMP.
AVG./MAX. AMB. 7500/10000
13800
95HV/60LV
4160Y/2402
1041/1388
30/40
H2
H3
H1
X3
X2
X1 X0
X0
X3
X2
X1
C D E F G C D E F G C D E F G
H3
H2
H1