Basler DECS-400 Instruction manual - Features/functions
DECS-400 Digital Excitation Control System
6
FEATURES/FUNCTIONS
Voltage Regulation
The DECS-400 regulates the generator RMS voltage to
within 0.20% from no-load to full-load, utilizing digital
signal processing and precise regulation algorithms
developed by Basler Electric, using the experience
gained over longer than a decade of manufacturing
tens of thousands of digital voltage regulators.
Output
The DECS-400 supplies an isolated output signal of 4-
20 mA, 0-10 Vdc, or ±10Vdc to the firing or control
circuits of external power stages. The dc current
produced by the power stages provides excitation to
the field of the generator or the exciter. The DECS-400
can control virtually any bridge capable of accepting
these signals, that is suitable for use on synchronous
generators/motors.
Stability
The DECS-400 utilizes proportional (P), integral (I) and
derivative (D) stability control. DECS-400 has
preprogrammed stability (PID) settings for both main
field (20 settings) and exciter field (20 settings)
applications. Thus, a suitable standard stability set is
available for most machines and applications. The
DECS-400 also provides an additional setting group
that can be customized to provide optimum generator
transient performance. Setup software includes a PID
selection program to assist in choosing the correct
PID settings. The DECS-400 also provides for custom-
izing the stability and transient performance of the
minimum and maximum Excitation Limiters, the VAR/
PF controllers, and the stator current limiter, by
providing additional stability adjustments.
Two PID Setting Groups
The DEC-400 provides for two sets of PID settings to
optimize performance under two distinct operating
conditions, such as with a Power System Stabilizer
(PSS) in or out of service. A fast controller provides
optimum transient performance with the PSS in
service, while a slower controller can provide improved
damping of first swing oscillations with the PSS off line.
Optional Power System Stabilizer
The DECS-400 may be purchased with an integral
Power System Stabilizer function that duplicates the
excellent performance of the Basler PSS-100 Power
System Stabilizer without the complications of an
additional control device. The PSS provides damping
for local mode, inter-area and inter-unit oscillations in
the 0.1 to 5.0 Hz range. The PSS incorporated in the
DECS-400 is a dual-input, IEEE type PSS2A/2B
stabilizer that utilizes the "integral of accelerating
power" algorithm. The PSS can also be programmed
to respond to frequency only if required for unusual
applications. Required inputs include three phase
voltages and two or three phase line currents.
Underfrequency Limiter
or V/Hz Ratio Limiter
DECS-400 includes a customer selectable choice of an
Underfrequency Limiter or a V/Hz Ratio Limiter to avoid
overfluxing the generator or other connected magnetic
devices. The under-frequency limiter slope can be set
at 0-3 PU Volts/Hz in 0.1 PU increments, and the
frequency roll-off kneepoint can be set across a range
of 15 to 90 Hz, in 0.1Hz increments, with fixed voltage
above the knee frequency. The V/Hz Ratio Limiter
regulates voltage based on a customer defined V/Hz
SPECIFICATIONS, continued
Type Tests
Shock:
IEC 60255-21-2
Vibration:
IEC 60255-21-1
Humidity:
IEC 68-1, IEC 68-2-28
Dielectric Strength:
IEEE 421.3
Transients:
IEEE C37.90.1-1989
Impulse:
IEC 60255-5
Surge Withstand Capability:
IEEE C37.90.1-1989
Radio Frequency Interference: IEEE C37.90.2
Electrostatic Discharge:
IEEE C37.90.3 Draft 2.3
Agencies
CE Compliant
UL recognized per Standard 508 and Standard CAN/CSA-C22-2
Number 14-M91, UL File Number E97035.
GOST-R certified per the relevant standards of Gosstandart of Russia
Byelorussian certified
Environment
Operating Temperature: -40 to 60°C (-40 to 140°F)
Storage Temperature: -40 to 85°C (-40 to 185°F)
Physical
Weight: 6.1 kg (13.5 lb)
Size: See Figure 1 on page 9 for DECS-400 dimensions.