S&C BankGuard PLUS, Инструкции по установке

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9 1011-530
to 7 series groups per phase (interpolate between the curves for S = 6 and S = 8). Here,
V
n
= 0.0043 per unit.
Similarly, for F = 2, enter the graph at 16.67 on the horizontal scale. Follow this up to a
point corresponding to 7 series groups per phase. Here, V
n
= 0.0093 per unit.
To convert V
n
to an actual voltage, multiply by the system voltage V
L-n
:
For F = 1,
For
F
= 2,
To determine the lockout level, calculate the midpoint value between V
n
for F = 1 and
V
n
for F = 2 (= F
c
):
Thus, the desired lockout level for this capacitor bank is 949 volts.
Formula Method
To calculate the lockout level for the capacitor bank:
A. Calculate V
o
for a series of steps corresponding to increasing values of F (up to and
including F
c
) using the following formulas:
B. For each value of F used in Step A, calculate V
n
:
C. Determine the desired lockout level: the midpoint between the V
n
(actual voltage) for the
critical step F
c
and the V
n
(actual voltage) for F
c-1
.
Formula Method – Example 1
An installation has the following profile:
•
Highest anticipated continuous system line-to-neutral voltage ( V
L-n
): 20 kV
•
Nameplate rating of the capacitor units ( V
r
): 9.96 kV
•
Number of series groups per phase ( S ): 2
•
Number of capacitor units in parallel per series group ( P ): 10
V
n
0.0043 139440 volts
×
600 volts = =
V
n
0.0093 139440 volts
×
1297 volts = =
600 volts 1297 volts +
2
------------------------------------------------------ 949 volts =
V
o
(volts)
3 P
( )
V
L n –
2 F 3 S
( )
P F –
( )
+
------------------------------------------- =
V
o
(per unit)
V
o
(volts)
V
r
------------------------ =
V
n
(volts)
F
( )
V
L n –
2 F 3 S
( )
P F –
( )
+
------------------------------------------- =