ABB | SACE Tmax XT
54 | © 2019 ABB | 1SDH002039A1002 - ECN000093027 - Rev. A
Protections | 3 - Voltage Advanced protections
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Parameter
Description
Default
Threshold Ul
This is the voltage that determines the change in trip threshold I20;
the behavior differs, depending on the mode selected
(1)
The value is given as both absolute value (Volts) and relative value (Un)
and can be set within the range: 0.2 Un to 1 Un in 0.01 Un steps
1 Un
Threshold Uh
The parameter is shown by the Lin curve and contributes towards I20
trip threshold calculation:
• with voltage reading < Uh (and
≥
Ul), the threshold changes
gradually
(1)
• with voltage reading
≥
Uh, the threshold is I20
The value is given as both absolute value (Volts) and relative value (Un)
and can be set within the range: 0.2 Un to 1 Un in 0.01 Un steps
1 Un
Threshold Ks
I20 threshold calculation constant.
The value is given as percentage of threshold I20 and can be set
within the range: 0.1 I20 to 1 I20, in 0.01 steps
0,6 I20
Time t20
This is the trip time of the protection.
The value is given in seconds and can be set within the range: 0.05 s
to 30 s, in 0.01 s steps
0.1 s
(1)
Trip threshold (depending on the operating curve)
Mode
Voltage reading
Trip threshold
Scal
< UI
Ks x I20
≥
UI
I20
Lin
< UI
Ks x I20
≥
Ul (e < Uh)
((I20 x ( 1 - Ks ) x ( U
mis
- Uh ) ) / (Uh - Ul) ) + I20
Limitations and additional functions
The block functions can also be accessed by means of the service connector (via Ekip Connect) or by
connection to the system bus (page 75).
S(V) Protection
I21
t
t21
I
S2(V)
Function
S2(V) protection functions in the same way as S(V) protection and protects against short-circuits, with
threshold sensitive to the voltage value.
It is independent of S(V) protection, thus thresholds and functions of the two protections can be programmed
so as to take advantage of different plant solutions (example: signaling with S(V) and open command with
S2(V) or vice versa, or both S(V) and S2(V) for signaling or tripping).
If the current of one or more phases exceeds threshold I21 for longer than time t21, the protection activates
and sends a TRIP command.
Threshold I21, after a voltage drop, varies in two different modes:
•
Step
provides for a stepped variation, depending on parameters Ul2 and Ks2.
•
Lin
(linear) provides for a dynamic variation, depending on parameters Ul2, Uh2 and Ks2.
I21
V
I21
Ks2 x I21
Uh2
Ul2
I21
V
I21
Ks2 x I21
Ul2
Figure 29
To check and simulate the trip times in relation to all the parameters, please consult:
• the summary table of the protections with the calculation formulas (page 80)
• the graph with trip curve (page 90)
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