Sel 411L - Page 443

P.3.335
Date Code 20151029 Protection Manual SEL-411L Relay
Protection Functions
Protection Application Examples
We would have the following at Relay T:
CTRW := 2000 Current Transformer Ratio - Input W (1–50000)
CTRX := 100 Current Transformer Ratio - Input W (1–50000)
Enter the PT ratio and nominal secondary voltage according to Table 3.168.
We would have the following at relays S and T:
PTRY := 3000 Potential Transformer Ratio—Input Y (1.0–10000)
VNOMY := 115 PT Nominal Voltage (L-L)—Input Y (60–300 V, sec)
Relay Configuration
Configure the 87L element for three-terminal operation.
We would have the following at all relays:
E87L := Y Enable 87L Function (Y, N)
The steady-state charging current is as follows:
Equation 3.123
The tap setting at Terminal R (see the following in-line transformer settings) is
as follows:
Equation 3.124
As a result, the charging current in per unit at Terminals S and R is as follows:
Equation 3.125
Enable line-charging current and in-line transformer compensation for this
application. There is no voltage source at Terminal T. Therefore, line-charging
current compensation is enabled only at Terminals S and R.
In addition, enable one phase instantaneous and one inverse time overcurrent
element at each terminal. These elements will provide backup protection. At
Terminal T, a ground instantaneous element is also necessary to provide
sensitive ground fault protection for the 69 kV delta winding of the
transformer.
We would have the following at relays S and R:
E87LCC := Y Enable Line Charging Current Compensation (Y, N)
We would have the following at Relay T:
E87LCC := N Enable Line Charging Current Compensation (Y, N)
We would have the following at all relays:
E87XFMR := Y Enable In Line Transformer Protection (Y, N)
E50P := 1 Phase Inst./Def.-Time O/C Elements (N, 1–4)
E51S:= 1 Selectable Inverse Time O/C Element (N, 1–3)
E32:= AUTO Directional Control (Y, AUTO)
EBFL1 := 1 Breaker 1 Failure Logic (N, 1,2)
I
CH
345 kV
3
------------------
2002010++ mi 0.008• •
mS
mi
--------
357 A primary==
Tap
225 1000•
3 345 200• •
-------------------------------------- 1.88 A==
I
CH
357 A
1000 51.88 A•
----------------------------------------------- 0.95 per unit==