V-RTU2000 Series
Chapter 10 - Analog AC Power Input Unit
Veesta - Remote Terminal Unit
Technical Specification Manual
Page 58 of 90
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10.2.2 Fault Current Detection Function
10.2.2.1
Fault-Based-Curve
One user programmable Fault-Based-Curve can be stored in the
ACPM Card Model VR-2749A. This can be used for time over-current
detection in the same as IEC, ANSI curves. The custom Fault-Based-
Curve has set-points for entering times to fault at the following
current levels (I/Ipu): 1.00 to 1.20 in steps of 0.05 and 1.20 to 6.00 in
steps of 0.4, and 6.0 to 16.0 in steps of 2.0. The ACPM then converts
these points to a continuous curve by linear interpolation between
data points.
(I/Ipu)
Fault
Time
(I/Ipu)
Fault
Time
(I/Ipu)
Fault
Time
1.00
0-65535 2.80
0-65535 6.00
0-65535
1.05
0-65535 3.20
0-65535 8.00
0-65535
1.10
0-65535 3.60
0-65535 10.0
0-65535
1.15
0-65535 4.00
0-65535 12.0
0-65535
1.20
0-65535 4.40
0-65535 14.0
0-65535
1.60
0-65535 4.80
0-65535 16.0
0-65535
2.00
0-65535 5.20
0-65535
2.40
0-65535 5.60
0-65535
10.2.2.2
Fault-Alarm-Curve
The required Fault-Alarm-Curve is established by programming a
Pickup Current and a Curve Multiplier. The Pickup Current is the
threshold current at which the fault detection starts timing, range from
0.05 to 16.00 CT. The Curve Multiplier allows shifting of the
programmed base curve in the vertical time direction, range from
0.00 to 100.00. The formula is:
T = M * Tfbc (at I/Ipu)
Where
T = Fault Alarm Time (ms)
M = Curve Multiplier
Tfbc = Fault Base Time (ms) at I/Ipu
I = Input Current
Ipu = Pickup Current
10.2.2.3
Set-point Group
In VR-2749A ACPM Model, the set-points (Ip-pu, Mp) are used for all
three phase time over-current detection, and the set-points (Ig-pu,
Mg) are used for ground time over-current detection only. Sixteen
user programmable set-point groups (Ip-pu, Mp, Ig-pu, Mg) (G-00 to
G-15) can be stored in VR-2749A. (In other word, there are 16 phase
fault-alarm-curves
and
16
ground
fault-alarm-curves.)
Via
communications, host can select the active set-point group remotely,
and the active group no, the active Ip-pu, the active Mp, the active
Ig-pu, and the active Mg value can be read-back.
