Basler DECS-200-2L excitation system

Basler DECS-200-2L excitation system

Product Overview and Technical Specifications

DECS-200-2L is an integrated excitation control system that controls the terminal voltage, reactive power, or power factor by adjusting the DC current of the generator excitation winding. The core parameters are as follows:

1.1 Input power supply

Control power supply (model optional): 16-60Vdc (30W), 85-132Vac 50/60Hz (50VA), 90-150Vdc (30W).

Operating power supply (excitation power): Select single-phase or three-phase input (50-500Hz) according to the required output DC voltage, corresponding to the following relationship:

DECS-200 output AC input voltage (nominal) input range apparent power

32Vdc 60Vac 56～70Vac 780VA

63Vdc 120Vac 100～139Vac 1570VA

125Vdc 240Vac 190～277Vac 3070VA

Attention: When supplying power directly from a power source that has already reached the rated voltage, an ICRM-15 surge current suppression module needs to be installed. The minimum building voltage is 3Vac.

1.2 Output Characteristics

Parameter 32Vdc, 63Vdc, 125Vdc

Rated continuous current 15Alc 15Alc 15Alc

Rated 10 second strong excitation voltage 50Vdc, 100Vdc, 200Vdc

Rated 10 second strong excitation current 30Adc 30Adc 30Adc

Minimum magnetic field resistance 2.13 Ω 4.2 Ω 8.3 Ω

Note: If three-phase input or magnetic field current is significantly lower than the rated value, the strong excitation voltage can be increased by 50%.

1.3 Voltage Transformer Input

Generator voltage transformer: single-phase or three-phase line voltage, with four selectable ranges (100/120V, 200/240V, 400/480V, 500/600V, corresponding to 50/60Hz).

Bus voltage transformer: single-phase line voltage, with the same four ranges.

1.4 Environment and Certification

Working temperature: -40 to+60 ℃; Storage: -40 to+85 ℃.

Anti vibration, anti impact, and salt spray comply with MIL-STD-810E.

Certification UL recognized（File E97035）、CSA certified、CE compliant、DNV、GOST-R、Byelorussian。

Installation and Wiring Guide

2.1 Mechanical dimensions and installation

DECS-200-2L dimensions: width 8.08 inches (205mm) x height 12.0 inches (304mm) x depth 6.76 inches (171mm), weight 14 pounds (6.35kg). Installation using panel opening (see manual figure 5 for opening size) requires the use of a front mounting bracket (Basler P/N 9360107100). You can also choose the IDP-800 remote interactive display panel (7.5-inch color touch screen), which can be installed up to 4000 feet away through RS-485.

2.2 Typical Wiring Diagram

Figure 1 in the manual provides a typical AC connection diagram, with the main wiring including:

Operating power supply: terminals PMG A, B, C (three-phase or single-phase).

Generator voltage detection: terminals P1, P2, P3 (single-phase or three-phase).

Bus voltage detection: terminals S1 and S2 (single-phase).

Excitation output: terminals F+, F -.

Parallel compensation CT: terminals C1 and C2 (cross current).

Switching input: dry contact (requires external supply of 24Vdc), including start stop, up/down, AVR/FCR selection, parallel/single machine switching, alarm reset, etc.

Analog input: Two sets, optional ± 10Vdc or 4-20mA, used for power system stabilizer (PSS) or remote set point.

Communication port:

COM0: RS-232 (front panel), ASCII command, used for local PC connection.

COM1: RS-232 (right side), used for dual machine redundant tracking.

COM2: RS-485 (left side), Modbus protocol, half duplex, 1200-19200bps.

2.3 Special precautions for redundant systems

When using dual DECS-200 redundant applications, an interconnect cable (Basler P/N 931030032) is required to connect the COM1 port.

The excitation output must be connected in parallel to the magnetic field winding through an external contactor, and a flywheel diode module (Basler P/N 9293600101) must be connected in parallel to the outside of the magnetic field winding to provide a continuous current path during switching, avoiding measurement errors or excitation interruptions caused by current interruption.

Operation mode and adjustment function

DECS-200 supports four main adjustment modes, which can be switched through switch input or communication, and has internal automatic tracking (non active mode tracks active mode) to achieve disturbance free switching. Optional external automatic tracking (between two machines).

3.1 Automatic Voltage Regulation (AVR)

AVR is the default mode, maintaining a constant generator terminal voltage with an accuracy of ± 0.25% (from no-load to full load) and a steady-state accuracy of ± 0.1%. Soft start function: The soft start time (1-7200 seconds) can be set, and the voltage smoothly increases from the residual value to the set value during voltage building to avoid voltage overshoot.

3.2 Field Current Regulation (FCR)

FCR is a manual backup channel that directly controls the excitation current with an accuracy of ± 1%. It does not rely on voltage detection, so it can be used as a backup during demagnetization detection. In FCR mode, all limiters (OEL, UEL, SCL) only sound an alarm and do not activate.

3.3 Reactive power regulation (Var)

When the generator is connected to the grid, DECS-200 can adjust the reactive power output to the specified value (kvar) with an accuracy of ± 2% of the rated kVA.

3.4 Power factor regulation (PF)

Maintain a constant power factor during grid connection, with an accuracy of ± 0.02 PF (within the range of 10% to 100% active power). For example, setting PF=0.80, the actual adjustment range is 0.78-0.82.

3.5 Parallel compensation method

Reactive Droop: Reduce the voltage setting value proportionally based on the reactive current, with an adjustment range of 0-30% (rated voltage).

Reactive Differential: By using an external CT (1A or 5A) to detect the difference in reactive current between each machine, adjust the excitation to evenly distribute the reactive power. If the CT burden is less than 1VA, existing quantitative CT can be utilized.

Line voltage drop compensation: shares parameters with sag, with an adjustment range of -30% to 0.

3.6 Setpoint control mode

DECS-200 supports multiple external setpoint adjustments:

Up/down contact input (dry contact)

Auxiliary analog input (4-20mA or ± 10Vdc)

RS-232 (ASCII command)

RS-485（Modbus）

The traversal speed of each operation mode is independently adjustable, allowing users to customize the speed and feel. In addition, the pre positioning input function can drive the current mode to the preset operating point, and the "hold" or "release" mode can be selected.

Limiter and protection function

DECS-200 integrates multiple limiters to protect the generator and exciter.

4.1 Overexcitation Limit (OEL)

OEL works in all modes (except FCR) to prevent overheating of the magnetic field winding. Provide two types:

Summing Point:

Online: Three current levels: high, medium, and low. High and medium levels can be set with duration limits (0-10 seconds, 0-120 seconds) respectively, while low levels can operate continuously.

Offline: There are two current levels, high and low, and the high level can be set with a time limit (0-10 seconds).

Takeover: Adopting inverse time characteristics, users can set high/low current values and time scales (Time Dial), and different curves can be selected online/offline.

4.2 Underexcitation Limit (UEL)

Prevent the generator from stepping out of step or overheating of the end iron core due to excessive phase advance. Optional:

Internally generated curve (based only on reactive power value at 0kW)

Customizable 5-point polyline (power reactive power) to match the generator capacity curve.

4.3 Stator current limit (SCL)

Monitor the stator current to prevent overheating of the stator winding. The high current level can be set with a time limit (0-60 seconds), while the low current level can operate continuously. SCL only alarms without restrictions in FCR mode.

4.4 volts per hertz limit (V/Hz) or underfrequency limit

Optional:

Underfrequency limiter: slope adjustable from 0 to 3.0 P.U./Hz, transition frequency adjustable from 45 to 65Hz.

V/Hz ratio limiter: Adjust the set point based on the set slope clamp.

4.5 Excitation diode monitoring (EDM)

Detect open/short circuit faults in the rotating diode of the brushless generator. Users are required to input the number of main poles of the generator and the number of poles of the exciter (2-20 each, even numbers), set the ripple threshold and delay (10-60 seconds for open circuit and 5-30 seconds for short circuit). EDM is achieved by analyzing specific harmonic components in the excitation current.

4.6 Generator protection function

Protection function setting range

Generator overvoltage (59) 0-30kV, delay 0.1-60 seconds

Generator undervoltage (27) 0-30kV, delay 0.5-60 seconds

Demagnetization (40) 0-3000Mvar, delay 0.1-9.9 seconds

Loss of test (60FL) 0-100% rated voltage, delay 0-30 seconds

Magnetic field overvoltage (59F) 1-325Vdc, inverse time delay 0.2-30 seconds

Magnetic field overcurrent 0-16Adc, inverse time limit (ANSI C50.13)

Sequential event recording and waveform recording

5.1 Sequential Event Recording (SER)

DECS-200 monitors changes in I/O status, system operation status, and alarm events, and can store 127 time stamped events, which can be read through BESTCOMS software. The time format supports 12/24 hours and daylight saving time, and the date format is d-m-y or m/d/y.

5.2 Oscillography

It can store 8 waveform records, with a maximum of 6 variables per record (such as generator voltage, current, frequency, kW, power factor, excitation voltage, excitation current). Sampling rate: Each record contains 600 data points, and the number of pre trigger points can be adjusted from 0 to 599. The sampling interval is 4ms to 10 seconds (total recording time is 2.4 seconds to 6000 seconds). Trigger method: BESTCOMS manual, logic trigger, level trigger (such as excitation current exceeding limit) or alarm trigger. The recorded data complies with the IEEE COMTRADE standard and can be viewed using Basler BESTwave software.

Communication and software tools

6.1 BESTCOMS ™  Configure software

Comes with Windows based PC software, including:

PID parameter selection program (recommended stability settings based on excitation system type)

Read and write all parameters

Real time monitoring (12 parameters including voltage, current, frequency, power factor, etc.)

Remote control (excitation, mode switching, set point adjustment)

Event recording and waveform data extraction

6.2 Modbus Protocol (RS-485)

The COM2 port supports Modbus RTU half duplex, with a speed range of 1200-19200bps and a communication distance of up to 4000 feet. The manual provides complete register mapping, making it convenient for users to develop custom monitoring systems.

6.3 Password Protection

All parameters can be viewed without a password, but modifying parameters requires entering a password. Two levels of permissions: global access (all parameters) and limited operator access (common setpoints).

Typical troubleshooting and maintenance recommendations

7.1 Common fault phenomena and solutions

Possible causes and solutions for the phenomenon

Excitation cannot be established, no output. 1. Control power supply is missing or voltage does not match

2. The power supply is not connected or the fuse is blown

3. Soft start incomplete inspection of terminal B+and B - voltage; Check PMG input; Confirm that the soft start time has passed or increase the soft start time

Voltage instability or oscillation PID gain is not suitable. Use BESTCOMS PID selection program to readjust, or manually adjust Kp, Ki, Kd

After parallel operation, check the polarity of the cross flow CT for uneven reactive power compensation or insufficient gain (ID+should be higher than ID - when outputting inductive energy); Increase CrossCurrentGain

Rotating diode fault false alarm ripple threshold set too low; Pole input error calibration EDM parameters: During actual operation, observe the normal ripple percentage and set the threshold to 3 times the normal value (open circuit) and 50 times the normal value (short circuit)

Check if the excitation current is indeed lower than the Loss of Field setting value when the demagnetization protection misoperates and the demagnetization setting value is too high or the delay is too short; Adjust according to the characteristics of the generator

Communication failure (RS-485), address conflict, missing terminal resistance, baud rate mismatch, confirm Modbus address uniqueness; Add a 120 Ω terminal resistor at the beginning and end of the line; Check baud rate, data bits, and parity bits

7.2 Regular maintenance recommendations

Check every six months whether the voltage of the control power supply and operation power supply is within the specifications.

Regularly read SER and waveform records to analyze for duplicate alarms.

Check if the external flywheel diode module (redundant system) is intact, with no open or short circuits.

Clean the cooling vents (natural cooling, fanless).

7.3 Firmware Upgrade

The DECS-200 firmware can be upgraded using BESTCOMS through the COM0 port. Backup all parameters before upgrading. Power off is strictly prohibited during the upgrade process.

Accessories and spare parts

Name Basler P/N Purpose

Front installation bracket 9360107100 panel opening installation

Dual machine interconnection cable 931030032 redundant system connection COM1 port

Control power isolation transformer BE31449-001 needs to be isolated when using dual control power supplies

Flywheel diode module 9293600101 redundant system excitation output freewheeling

ICRM-15 Surge Suppression Module - Suppresses surge current when operating power supply reaches rated voltage

IDP-800 Interactive Display Panel - Remote HMI, RS-485 connection, up to 4000 feet away