Basler Electric DECS-400 - Manual (Page 59)

9369700990 Rev R 47
(0.49 x kW
pu
x kW
pu
−
1.0) x kvar_level
Where:
kw_pu = metered kW level in per-unit
kvar_level = user setting for kvar in per-unit
The user-defined curve can have a maximum of five points. This curve allows the user to match a specific
generator characteristic by specifying the coordinates of the intended leading reactive power (kvar) limit at
the appropriate real power (kW) level. A typical user-defined UEL curve is shown in Figure 15.
Figure 15. User-Defined UEL Curve
The levels entered for the user-defined curve are defined for operation at the rated generator voltage. The
user-defined UEL curve can be automatically adjusted based on generator operating voltage by using the
UEL voltage dependency real-power exponent. The UEL voltage dependency real-power exponent has a
setting range of 0 to 2 with an increment of 1. When a setting of 1 or 2 is entered, the user-defined UEL
curve is automatically adjusted based on the ratio of the generator operating voltage divided by the
generator rated voltage raised to the power of the UEL voltage dependency real-power exponent.
Underfrequency Limiter
When the generator frequency decreases below the corner frequency for the underfrequency slope
(Figure 16), the DECS-400 adjusts the voltage setpoint so that the generator voltage follows the under-
frequency slope. Settings for the corner frequency and slope enable the DECS-400 to precisely match the
operating characteristics of the prime mover and the loads being applied to the generator. A Corner
Frequency setting of 15 to 90 hertz may be entered in 0.1 hertz increments. A per-unit Slope setting of 0
to 3 may be entered in 0.01 increments.
When an underfrequency condition occurs, the DECS-400 issues an underfrequency annunciation
through the front panel HMI. An annunciation may also be assigned to one of the DECS-400
programmable relay outputs.
45.0k
37.5k
30.0k
22.5k
15.0k
7.5k
0.0
R
e
a
c
ti
v
e
P
o
w
e
r
A
b
s
o
rb
(
v
a
r)
x
1
0
0
0
45.0k 37.5k 30.0k 22.5k 15.0k 7.5k 0.0
Real Power Generate (W) x 1000
D2851-25
06-28-05
DECS-400 Functional Description