Description

BASLER ELECTRIC DECS-250N-LN3CN1N

I. Basic Information

Model: DECS-250N-LN3CN1N

Serial No: H03112244

Brand: Basler Electric

Product Line: High-power digital excitation control system for brushless synchronous generators, with 20A continuous field output, three-phase true RMS sampling, five adjustable operation modes, integrated generator protection, PSS function, multi-protocol industrial communication and programmable logic. It realizes stable voltage regulation for isolated grid, reactive power balance for grid-parallel units and fault safety interlock, widely applied in thermal, hydropower, distributed energy and industrial captive power plants for excitation renovation and new projects.

Product Positioning

DECS-250N is a full-function high-capacity excitation regulator equipped with dual auto-tunable PID groups, comprehensive excitation limiters and integrated relay protection. It supports hot standby redundant operation, multi-unit reactive load sharing, SOE sequence recording and fault oscillography. With abundant I/O and communication expansion capability, it can seamlessly connect with DCS/SCADA systems, effectively suppress power grid low-frequency oscillation, prevent generator loss of excitation and rotor overheating, serving as the core control device for medium and small synchronous generator excitation systems.

Hardware Architecture

Flame-retardant 3U rack-mounted metal housing with full PCB conformal three-proof coating, consisting of six core functional units: three-phase isolated voltage/current sampling unit, six-SCR full-bridge field power output unit, multi-mode PID closed-loop control unit, integrated protection & excitation limiting unit, programmable I/O & analog remote setpoint unit, multi-bus communication & debugging HMI unit. It supports AEM/CEM series expansion modules for I/O capacity expansion and dual-machine redundant master-slave tracking operation.

Mounting Specification

Standard 19-inch 3U rack installation, compliant with IEC vibration, humidity cycling and wide-temperature reliability standards for direct spare replacement without primary wiring modification of sampling and field power loops.

Dimension: 133mm(H)×483mm(W)×265mm(D), net weight: 3.8kg.

Compatible Systems

Hardware: PMG permanent magnet generator, voltage/current transformers, redundant interlock contactors, shielded sampling cables, AEM-2020/CEM-2020 expansion modules, 24VDC control power supply;
Software: BESTCOMSPlus configuration, online monitoring, oscillography analysis and firmware upgrade tool;
Upper Systems: Power plant DCS, SCADA dispatching platform, generator protection devices, energy management system;
Application Industries: Hydropower/thermal/gas power plants, distributed energy stations, oil & gas captive power stations, marine synchronous unit excitation renovation projects.

Product Characteristics

Three-phase true RMS wide-range sampling adapts to distorted harmonic grid conditions, with voltage regulation static accuracy ≤±0.5% and fast dynamic response to suppress voltage fluctuation under load disturbance.
Five bumpless switching operation modes with dual auto-tuning PID parameters greatly shorten on-site commissioning time and adapt to variable high/low load operating conditions.
Integrated protection plus multi-excitation limit logic ensures safe shutdown and excitation blocking under abnormal working conditions to avoid major generator equipment accidents.
Redundant multi-link communication supports centralized plant-wide automatic control and balanced reactive power distribution for multiple grid-connected generators.
Mass SOE timestamped event storage and fault oscillography facilitate power grid accident traceability and excitation parameter optimization verification.
User-defined programmable logic meets personalized interlock control requirements; wide-temperature three-proof industrial design supports long-term unattended stable operation in harsh control room environments.

II. Technical Specifications

2.1 Electrical Parameters

Control Power: DC 22~28V, typical power consumption 22W
Field Operating Input: Single/three-phase AC 50~420Hz, 120/240/480Vac optional
Rated Field Output: 20A DC continuous, 30A DC forced excitation for 10s, 32/63/125V field voltage optional
Relay Contact Rating: 7A resistive @ 24/125VDC, dielectric withstand voltage 2000VAC 1min, ±4kV ESD, ±2kV EFT protection.

2.2 Sampling Parameters

Voltage Input: 1/3-phase three-wire, 100~600Vac range, burden＜1VA per phase
CT Current Input: 1A/5A AC optional, burden＜1VA, with cross-current compensation for parallel reactive sharing
Analog Remote Setpoint: 4~20mA / ±10VDC, measurement accuracy ±1%FS, frequency accuracy ±0.1Hz.

2.3 Communication Parameters

Local Debug: USB Type-B, RS232; Field Bus: RS485(Modbus RTU), CAN; Remote Monitoring: 100M Ethernet(Modbus TCP), supports SNTP time synchronization.

2.4 Environmental Specifications

Operating Temperature: 0℃ ~ +70℃; Storage Temperature: -40℃ ~ +85℃
Relative Humidity: 5%～95%RH, non-condensing, no corrosive gas
Vibration Compliance: IEC 60068-2-6, protection class IP20 (IP30 in sealed cabinet), CE & UL certified.

2.5 Mechanical Parameters

Mounting: 19-inch standard 3U rack mount
Dimension: 133mm×483mm×265mm, net weight: 3.8kg
Housing: Anti-static coated flame-retardant cold-rolled steel plate, front status LED, rear multi-functional terminal blocks.

III. Key Features

3.1 Bumpless Multi-Mode Closed-Loop Excitation Regulation

Supports AVR/FCR/FVR/PF/VAR five control modes with dual auto-tuning PID groups and optional PSS2A/2B/2C power system stabilizer to restrain grid low-frequency oscillation and improve transient stability of grid-connected units.

3.2 Full-Range Excitation Limit & Integrated Generator Protection

Equipped with OEL/UEL/V/Hz/stator current/var limit functions and comprehensive fault protection including over/under voltage, over/under frequency, reverse power, loss of excitation, field short circuit, to realize fault excitation blocking and safe unit isolation.

3.3 Multi-Unit Parallel Reactive Sharing & Dual Hot-Standby Redundancy

Realizes reactive power balance via bus communication; master-slave redundant regulators track setpoints in real time for bumpless switching upon single device fault, eliminating risk of generator voltage collapse caused by single excitation equipment failure.

3.4 High-Capacity SOE Recording & Fault Oscillography Analysis

Non-volatile memory permanently stores millisecond-timestamped protection actions, status changes and limit events; pre/post-fault multi-channel waveform recording supports off-line accident analysis and excitation parameter optimization.

3.5 Programmable Logic & Flexible System Expansion

Custom interlock, alarm and sequential control logic can be configured via BESTlogic™Plus; I/O expansion modules and multi-protocol communication realize seamless data interaction with upper automation systems for remote closed-loop regulation and centralized monitoring.

IV. Working Principle

After power-on self-test of sampling, power, I/O and communication circuits, the regulator loads preset parameters into standby mode. It collects generator voltage and current signals via isolated PT/CT loops, executes PID closed-loop calculation to adjust SCR rectifier trigger pulses and stabilize terminal voltage or reactive power. Excitation limit and protection functions monitor operating parameters in real time; faults will lock field output and latch fault timestamps. Redundant devices synchronize control setpoints for seamless switchover, and all operation events are timestamped and stored for post-failure data analysis.

V. Application Scenarios

Medium & small thermal/hydropower/gas turbine synchronous generator excitation control for isolated and grid-connected working conditions.
Oil, mining, chemical captive power plants and distributed energy stations for legacy analog AVR excitation system upgrading.
Marine and mobile vehicle power stations for multi-unit parallel voltage stabilization and reactive power balance control.
Photovoltaic/wind power peak-shaving synchronous condenser excitation regulation for grid voltage support and oscillation suppression.
Metallurgical and cement waste heat power plant dual-redundant excitation system renovation to improve continuous power supply reliability.