Basler DECS-250 - 1 Introduction; Features and Functions

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DECS-250 Introduction
1 • Introduction
DECS-250 Digital Excitation Control Systems offer precise excitation control and machine protection in a
compact package. DECS-250 adaptability to many applications is assured through configurable contact
inputs and outputs, flexible communication capabilities, and programmable logic implemented with the
provided BESTCOMSPlus
®
software.
Features and Functions
DECS-250 features and functions include:
• Precise excitation control for synchronous generator or synchronous motor applications
o Power factor and var metering values will be opposite in motor mode
• Five excitation control modes:
o Automatic Voltage Regulation (AVR)
o Field Current Regulation (FCR)
o Field Voltage Regulation (FVR)
o Power Factor Regulation (PF)
o Var Regulation (var)
• Three pre-position setpoints for each excitation control mode
• Internal tracking between operating mode setpoints and external tracking of a second DECS
excitation setpoint
• Two PID stability groups with Auto Tune feature
• Remote setpoint control input accepts analog voltage or current control signal
• Grid code functions
o Connect and disconnect
o Active power control
o Reactive power control
• Real-time metering
• Optional automatic synchronizer
• Optional integrated power system stabilizer (IEEE Std 421.5 type PSS2A/2B/2C)
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 Overexcitation: summing point and takeover
o Underexcitation
o Stator current
o Reactive power (var)
o Underfrequency
• Twenty protection functions:
o Generator undervoltage (27)
o Generator overvoltage (59)
o Loss of sensing (LOS)
o Overfrequency (81O)
o Underfrequency (81U)
o Reverse power (32R)
o Loss of excitation (40Q)
o Field overvoltage
o Field overcurrent
o Loss of PMG
o Exciter diode failure
o Sync-check (25)
o Eight configurable protection elements