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Published for the Basler Electric Power Systems Group #EX-NEBB • July 2010

APPLICATION✐

Notes

Basler Offers Solutions for Replacing Aging SF and GX RegulatorsThe NEBB is a six-

model series of voltageregulators designed byABB Oslo in the 1970s.There are an estimated5000 units currentlyoperating in the world,mainly in marine andoffshore applicationsand some on-shoregenerators. NEBBAVRs were basicdesigns using theavailable technology ofthe time and met theapplication needs.See Table 1.

Other than thediodes, no specificprotection was includedand generator opera-tion on a networkneeded additionalcomponents to providepower regulation. Thede-excitation circuitwas generally com-posed of a tripping coilcontrolled by externalprotection devices.

Typically, this AVRwas controlling 800 to 2500 Kva generators. Now,products or parts replacement have become extremelydifficult to obtain. Basler has experience in the renova-tion of these systems and can offer solutions either usingthe existing exciter or replacing it.

Figure 1: Single line diagram representing an SF2 bk or SR7 voltage regulator.

NEBB AVR Type SF2 SF2a SF2 ak SF2 b SF2 bk SF7

Parallel Droop Operation No Yes Yes Yes Yes Yes

Compounding Circuit No No Yes No Yes Yes

190 Vdc9 Adc

50 to 110 Vdc115 to 140 Adc

Current/Voltage Output

Table 1: NEBB Product RangeFigure 2: Basler DECS-200

mounted in cabinet with MVC300

Basler Proposed Renovation Solutions forthe SF RegulatorsOption 1

The first is dedicated to brushless generators wherethe NEBB SF7 was usually mounted inside the genera-tor terminal box. In this configuration, the brushlessexciter was maintained. To replace it, Basler offered a

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Figure 3: Option 2 - Completeconversion of the brushless system to a

static operation via Basler cabinet

The GX 300 typically included the following:• Three phase voltage sensing• Measurement of reactive current for parallel

operation• Frequency fall-off voltage limitation• Auto-Follow control in dual channel systems

(option)• External control of Var/PF and voltage• Minimum/maximum settings for the excitation

current

GX 300 Regulator Features

Figure 4: GX 300 and GX 500were replacements for NEBB voltage

regulators

Figure 5: Basler replaces the agingregulator with a DECS-200 on a

standard mounting plate

DECS-200 mountedin a cabinet andequipped with anMVC 300 (manualvoltage control) toprovide an addi-tional manual backup device.

Option 2The second is a

complete conver-sion of thebrushless system toa static operation.This was done byremoving theexcitation systemand associatedcompound circuits,including theexciter.

In order to meet space requirements, a double-sided cubicle was designed to accommodate control andpower components in one single-door panel.

Solutions for the GX 300 and 500Regulators

First introducedin 1986, the GX 300and GX 500 werereplacements for theformer NEBBvoltage regulators.

Designed tooperate in Shunt orPMG poweredapplications, theanalogue systemshave been the ABBexcitation systemstandard for severalyears until theBasler DECS-15

became its standardreplacement bothfor new and renova-tion equipment.They were usedprimarily inbrushless exciterapplications wherethe exciter wascontrolling the mainfield of the genera-tor.

These AVRsgenerally requiredseveral externalmodules to provideexciter diodemonitoring, manualcontrol and otherfeatures. Nowadaysthe DECS-200 offersa complete solutionto cater to thereplacement ofthese AVRs in onepackage or in dual application with bumpless transferfrom the main operating unit to its back up AVR.

The Basler proposed renovation solution is astandard mounting plate generally sized or adapted tomeet the space previously taken by the GX AVR.

The DECS-200 and DECS-400 offer superiorfunctionalities and capabilities that enables users toextend the life span of generators and better protectthem from harmful conditions. Table 2 on the next pagesummarizes these additional features.

For More InformationVisit www.basler.com and download more informa-

tion on Basler's Compact Digital Pre-packaged AVRMounting Plate Solutions. You also can downloadBulletin SZM for details on Basler’s DECS-200 andBulletin SZF for more information on the features ofthe DECS-400. You can also access product documenta-tion and Application Notes on the web site.

To discuss your specific application, consult theBasler factory at (618) 654-2341.

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Table 2: Comparison of Features

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FUNCTIONSDECS-200 / DECS-400

NEBB SF REGULATOR GX 300

AVR CONTROL YES YES YES

FIELD CURRENT REGULATION YES EXTERNAL MODULE EXTERNAL MODULE

FIELD VOLTAGE REGULATION DECS 400 NO NO

VAR/PF CONTROL YES EXTERNAL MODULE EXTERNAL MODULE

PARALLEL COMPENSATION YES YES YES

AUTO-TRACKING BETWEEN CONTROL MODES YES NO YES

AUTO-TRACKING WITH OPTIONAL UNIT

YES NO YES

UNDER/OVER EXCITATION LIMITING YES EXTERNAL MODULE YES

STATOR CURRENT LIMITING YES NO NO

EXCITER DIODE MONITOR YES EXTERNAL MODULE EXTERNAL MODULE

UNDERFREQUENCY COMPENSATION OR VOLT/HZ

LIMITERYES

UNDERFREQUENCY COMPENSATION

ONLY

UNDERFREQUENCY COMPENSATION

ONLYGENERATOR BACK UP

PROTECTIONField Overvoltage

Field OvercurrentGenerator OvervoltageGenerator UndervoltageLoss of FieldLoss of Sensing Voltage

OSCILLOGRAPHY / EVENT RECORDING YES NO NO

GENERATOR PARAMETERS METERING YES NO NO

TRENDING / LIVE MONITORING DECS-400 NO NO

COMMUNICATION PORTSRS485 YESRS232 YESEthernet DECS-400

INST

RU

MEN

TATI

ON

NO NO

CO

NTR

OL

MO

DES

GEN

ERA

TOR

PR

OTE

CTI

ON

YES NO NO

EX-NEBB (7/10)

www.basler.com

Route 143, Box 269, Highland, Illinois U.S.A. 62249Tel +1 618.654.2341 Fax +1 618.654.2351

e-mail: [email protected]

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Tel +86(0)512 8227 2888 Fax +86(0)512 8227 2887e-mail: [email protected]

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