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2018.01 / a

10

Electric Power Generation

UF OE

UF     S     V

R1         R2         U           N         F1         F2

R121

V

DC

V

DC

V

AC

Installation and maintenance

R121

AVRs

5657 en -

9 - STATIC TEST PROCEDURE

This test should only be attempted after 

making sure that the AVR has passed all 

multimeter checks. Connect the AVR to the 

single-phase variable voltage source as 

shown in diagram 1 in this manual.
1. Keep “V-TRIM” in the minimum position.
2. Keep “UF” in the fully anticlockwise position.
3. Increase the applied voltage. The lamp 

should glow increasingly brightly. At a voltage 

of around 90 V-95 V the lamp should go out 

slowly. Increase the  voltage again up to 

240 V. The lamp should stay OFF.

Decrease the voltage to below 90 V. The lamp 

should glow again.
4. Turn the “UF” potentiometer clockwise. The 

UF LED will glow. The lamp should go out 

slowly. Now turn “UF” potentiometer 

anticlockwise. The UF LED will go out. The 

lamp should glow brightly again.
5. It is difficult to prescribe a static test for 

checking the stability, as this is more easily 

detected during closed loop tests. However, a 

healthy AVR will behave as described below.

First keep the “S” potentiometer in the fully 

anticlockwise position. Perform the static test 

as described in steps 1, 2 and 3. The lamp will 

go out fairly quickly at 90 V-95 V and come on 

again quickly when the voltage is reduced to 

below 90 V. 

Now keep the “S” potentiometer fully 

clockwise,  and  perform  the  static  test  as 

described  in  steps  1,  2,  and  3.  The  lamp 

should go out much more slowly and come on 

again much more slowly. At the end of this test 

reset the potentiometer in the middle position. 
6. Turn the “V” potentiometer fully clockwise. 

Increase the voltage to 250 V. The “OE” LED 

should glow and the voltmeter at F1 and F2 

should read 95 V. Increasing the voltage to 

305 V will turn off the lamp.
7. Connect the 2K potentiometer at terminals 

R1 and R2. Turn the external potentiometer 

both fully clockwise and anticlockwise. The 

lamp should turn off and on alternately.

If the AVR behaves as described above 

then it is in good working order.

230 V 60 W 

Lamp

250 VAC

50 Hz

Variac

3 A

2K Potentiometer OR 

WIRE LINK

Summary of Contents for Leroy-Somer R121

Page 1: ...OE UF V S UF R1 R2 U N F1 F2 R121 R121 AVRs Installation and maintenance ...

Page 2: ...arning symbol for electrical danger to personnel All servicing or repair operations performed on the AVR should be undertaken by personnel trained in the commissioning servicing and main tenance of electrical and mechanical components When the generator is driven at a frequency below 28 Hz for more than 30 seconds with an analogue AVR its AC power supply must be disconnected WARNING This AVR can b...

Page 3: ...N OF THE AVR 4 3 TECHNICAL SPECIFICATION 5 4 MAIN FUNCTION OF THE AVR 6 5 AVR SETTINGS 7 5 1 V 7 5 2 UF 7 5 3 S 7 6 AVR CONTROLS 7 7 TROUBLESHOOTING CHART 8 8 MULTIMETER CHECKS 9 9 STATIC TEST PROCEDURE 10 10 DIMENSIONS 11 11 SPARE PARTS 12 11 1 Designation 12 11 2 Technical support service 12 Disposal and recycling instructions ...

Page 4: ...ard voltage and frequency Asoft start circuit is included which provides smooth control of the build up of generator output voltage A frequency roll off circuit continuously monitors the generator underspeed protection by reducing the generator output voltage in proportion with the speed below a threshold 2 OPERATION OF THE AVR The AVR is powered by the terminals of the AC generator with 110 V 220...

Page 5: ...0 Hz and below 58 5 Hz for 60 Hz 9 Voltage build up 2 Volts U N 10 Voltage regulation 1 at the AVR terminals 11 Thermal drift 1 for 30º C change in temperature 12 Response time less than 50 ms 13 Closed loop response typically 0 5 sec to recover 97 5 of the defined voltage for a field forcing ratio of 1 2 14 Sensing loss protection the voltage should disappear when the sensing circuit is open 15 O...

Page 6: ...ered by the terminals of the AC generator with 110 VAC 220 VAC at 50 60 Hz The regulated sensing voltage is based on the AVR input power MAIN FIELD STATOR 12 wires T1 to T12 identification Exciter field Fuse Slow blow 250 V 6 3 Amps Over excitation limit 50 Hz 60 Hz section Voltage setting Under speed Under speed Stability Voltage reference 2K POTENTIOMETER OR WIRE LINK red black Armature Varistor...

Page 7: ...ltage in proportion with the speed below the defined value The procedure for setting the UF potentiometer is as follows First select 50 Hz 60 Hz mode on the AVR Run the generator at 48 5 Hz for a 50 Hz system or 58 5 Hz for a 60 Hz system Turn the UF potentiometer until the UF LED blinks The potentiometer position at which the UF LED blinks is the correct UF potentiometer setting The factory defau...

Page 8: ...fuse failed Check and replace Voltmeter on the front defective Check and correct AVR defective repeated fuse blowing Replace after performing a static test Earthed exciter field Check and correct High voltage build up Incorrect setting Check and correct AVR defective Perform a static test and replace if necessary Low voltage build up Low prime mover speed Check and correct Incorrect setting Check ...

Page 9: ...ITY ZERO indicates a power device failure in both cases No further tests static or dynamic are allowed as they would lead to the fuse blowing The resistance between F2 and U both sides should be greater than 200 Kohms ZERO indicates a power device failure in both cases No further tests static test or dynamic tests are allowed and it will lead to the fuse blowing The resistance between U and N both...

Page 10: ...c test for checking the stability as this is more easily detectedduringclosedlooptests However a healthyAVR will behave as described below First keep the S potentiometer in the fully anticlockwise position Perform the static test as described in steps 1 2 and 3 The lamp will go out fairly quickly at 90 V 95 V and come on again quickly when the voltage is reduced to below 90 V Now keep the S potent...

Page 11: ...1 a 11 Electric Power Generation Installation and maintenance R121 AVRs 5657 en 10 DIMENSIONS 2 x HOLES Ø 6 mm COUNTER BORE 9 mm x 5 DEEP 52 5 mm 52 5 mm 96 mm 83 mm 82 5 mm 1 mm V R1 R2 U N F1 F2 S UF OE UF ...

Page 12: ...vice epg leroy somer com or your closest contact whom you will find at www lrsm co support indicating the type and the code number of the AVR To ensure that our products operate correctly and safely we recommend the use of original manufacturer spare parts In the event of failure to comply with this advice the manufacturer cannot be held responsible for any damage 11 SPARE PARTS 11 1 Designation D...

Page 13: ...with local legislation regarding product disposal and recycling Waste hazardous materials The following components and materials require special treatment and must be separated from the alternator before the recycling process electronic materials found in the terminal box including the automatic voltage regulator 198 current transformers 176 interference suppression module 199 and other semi condu...

Page 14: ...2018 01 a 14 Electric Power Generation Installation and maintenance R121 AVRs 5657 en ...

Page 15: ...ient repair support and maintenance services Trust your alternator maintenance and support to electric power generation experts Our field personnel are 100 qualified and fully trained to operate in all environments and on all machine types We have a deep understanding of alternator operation providing the best value service to optimise your cost of ownership Where we can help Contact us Americas 1...

Page 16: ... 2018 01 a www leroy somer com epg 5657 en Linkedin com company Leroy Somer Twitter com Leroy_Somer_en Facebook com LeroySomer Nidec en YouTube com LeroySomerOfficiel ...

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