Basler Electric DECS-400 - Manual (Page 13)

9369700990 Rev R 1
General Information
The DECS-400 Digital Excitation Control System is a microprocessor-based controller that offers
excitation control, logic control, and optional power system stabilization in an integrated package. The
DECS-400 controls field excitation by providing an analog signal used to control the firing (output) of an
external power bridge. The DECS-400 monitors generator or motor parameters and acts to control, limit,
and protect the machine from operating outside its capability.
The optional, onboard power system stabilizer is an IEEE-defined PSS2A, dual-input, “integral of
accelerating power” stabilizer that provides supplementary damping for low-frequency, local mode and
power system oscillations.
Integral programmable logic provides excitation system control and annunciation based on DECS-400
contact inputs, operating mode status, excitation system parameters, and user-defined programming.
Setup and initial operation are facilitated by Basler Electric’s user-friendly BESTCOMS
™ PC software that
incorporates a test mode, flexible oscillography, and a graphic display of PSS test results.
The DECS-400 is designed for use with Basler Electric’s Interface Firing Module (IFM) and SSE or SSE-N
power bridges. However, it will work equally well with any power bridge with a firing circuit that is
compatible with the control signal output of the DECS-400.
Features
DECS-400 features and capabilities are listed below. The paragraphs following the list describe major
DECS-400 features and functions in more detail.
•
Five excitation control modes:
o Automatic Voltage Regulation (AVR)
o Field Current Regulation (FCR)
o Field Voltage Regulation (FVR)
o Power Factor (PF)
o Var
•
Two pre-position setpoints (with adjustable traverse rate) for each excitation control mode
•
Two PID groups
•
Programmable analog control output selectable for 4 to 20 mAdc, –10 to +10 Vdc, or 0 to
+10 Vdc
•
Remote setpoint control input accepts analog voltage or current control signal
•
Real-time metering
•
Integrated power system stabilizer (PSS):
o Generator or motor control modes, accommodates phase rotation changes between
modes
o Speed and power sensing or speed-only sensing
o Two-wattmeter or three-wattmeter methods of power measurement
•
Soft start and voltage buildup control
•
Five limiting functions:
o Stator current
o Overexcitation
o Underexcitation
o Underfrequency compensation
o Reactive power
•
Ten protection functions:
o Field overvoltage
o Field overcurrent
DECS-400 General Information