Basler Electric BE1-87T User Manual
Page 78
4-36
BE1-87T Installation
9171300990 Rev V
Three-Phase Units only: When using either
∆
2 or
∆
1 jumper positions, shown in Figure 2-4,
multiply the secondary current I
S
by the conversion factor (square-root of three) just as if the
CTs were connected in delta. Remember that, if system CTs are connected in delta, the same
square-root-of-three conversion factor must be applied.
HIGH
(INPUT 1)
TERTIARY
(INPUT 2)
LOW
(INPUT 3)
Step 5. Determine the spread ratio of the relay currents (largest/smallest):
Spread = 18.22/6.04 = 3.0
Step 6. Determine the Driving Input (DP), which we define as the input assigned to the smallest current
in Step 4:
Step 7. Determine the Driving Input Tap (T
1
), which must be less than the 4.45 capability of the BE1-
87T:
Choosing the 2.0 setting for the minimum inputs will yield maximum sensitivity.
Step 8. Determine the Desired Tap (T
D
):
TERTIARY
LOW
Step 9. Select taps by rounding T
D
to the nearest tenth:
HIGH
TERTIARY
LOW
T = 2.0
T = 6.0
T = 2.5
I
I
R
R
=
=
3.49
6.04
3
I
I
R
R
=
=
(18.22)
18.22
(1)
I
I
R
R
=
=
4.36 3
7.55
DP I
DP
M
=
=
HIGH (INPUT 1)
HIGH
T
1
2 0
= .
T
T I
I
D
R
R
2
1
2
1
2.0 18.22
6.04
6.03
=
)
(
=
)
(
=
T
T I
I
D
R
R
3
1
3
2.0 7.55
6.04
2.50
=
=
=
1
)
(
(
)