Nidec Leroy-Somer R121 Instruction Manual

OE UFV S UF
R1 R2 U N F1 F2
R121
R121
AVRs
Installation and maintenance

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AVRs
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SAFETY MEASURES
Before using your machine for the rst time,
it is important to read the whole of this
installation and maintenance manual.
All necessary operations and interventions
on this machine must be performed by a
qualied technician.
Our technical support service will be pleased
to provide any additional information you
may require.
The various operations described in this
manual are accompanied by recom-
mendations or symbols to alert the user to
potential risks of accidents. It is vital that
you understand and take notice of the
following warning symbols.
Warning symbol for an operation capable
of damaging or destroying the machine
or surrounding equipment.
Warning symbol for general danger to
personnel.
Warning 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 be incorporated in a EC-
marked machine.
This manual is to be given to the end
user.
© - We reserve the right to modify the
characteristics of this product at any time in
order to incorporate the latest technological
developments. The information contained in
this document may therefore be changed
without notice.
This document may not be reproduced in
any form without prior authorisation.
All brands and models have been registered
and patents applied for.
WARNING
This manual concerns the alternator AVR which you have just purchased.
We wish to draw your attention to the contents of this maintenance manual.

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CONTENTS
1 - GENERAL DESCRIPTION.................................................................................................4
2 - OPERATION 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

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1 - GENERAL DESCRIPTION
The R121 automatic voltage regulator
(AVR) is a compact, high-performance
encapsulated unit. It incorporates the latest
technology and efcient components to
achieve a high degree of miniaturisation
when used with 3-phase and 1-phase AC
brushless generators within its input and
output limits. The unit offers excellent
reliability.
The AVR provides DC excitation to the
exciter eld of a brushless generator to keep
the voltage within the approximate operating
limits from NO-LOAD to FULL LOAD.
The typical recovery time in the event of
sudden loading is around 0.5 sec. to recover
97.5% of the rated voltage. Transient
performance such as voltage dip and
recovery time is mainly determined by the
generator and exciter design parameters.
OptimumAVR performance can be obtained
by keeping full-load excitation to around
60 VDC.
The generator uses a true average sensing
circuit, dV/dt snubber and special lter
circuits to manage NON-LINEAR loads
such as battery chargers, DC motors, etc.
Voltage regulation is only guaranteed for
linear loads. Severely distorting NON-
LINEAR loads can cause regulation
problems.
Each AVR is tested prior to dispatch as part
of a quality plan, for standard 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 VAC rms at
50 Hz or 60 Hz. The sensing voltage, which
is the regulated voltage, is also based on the
input power. The AVR forms an important
part of the closed loop system comprising
the generator eld, generator armature and
the AVR.
The AVR rst builds up the generator voltage
from its residual levels to the rated voltage
value. When the generator is loaded, the
sensed voltage decreases and generates
an error voltage, which is required in order
for the closed loop system to work.
The AVR contains a high gain amplier.
Depending upon the value of the amplier
voltage (either high or low) the ramp
intersects the amplied voltage at a point,
which is either early or late in the half-cycle.
At this intersection point a starting pulse is
produced to trigger the power device.
When the power device is triggered early in
the half-cycle, more voltage is fed to the eld
and when triggered late in the half-cycle,
less voltage is transmitted to the eld.
In order to reduce the generator voltage at
low speed, a signal inversely proportional to
the speed is generated as an extra input.

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3 - TECHNICAL SPECIFICATION
1) Sensing input and Input power
- Voltage: 90 V to 277 VAC ±10%, 50/60 Hz
2) Output power
- Voltage:
• 95 VDC at 220 VAC Input
• 50 VDC at 90 VAC
- Current:
• 6 A DC
• 8 A for 30 sec. (when allowed by the eld
resistance)
3) Operating temperature: -20ºC to +70ºC.
4) Storage temperature: -40ºC to +80ºC.
5) Voltage setting: min ± 10% of rated
voltage.
6) External potentiometer voltage setting:
min ± 15% of rated voltage with 2 K
potentiometer.
7) Stability setting: can be adjusted to obtain
a correct transient response in steady state.
8) Under frequency roll-off setting: available
below 48.5 Hz for 50 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 dened voltage for a
eld forcing ratio of 1:2.
14) Sensing loss protection: the voltage
should disappear when the sensing circuit is
open.
15) Overexcitation protection: 95 VDC.
16) Protection fuse: 6.3 A, 240 VAC.
17) Potentiometer sealing: except for the
V-trim potentiometer, all potentiometers are
sealed.
18) Frequency roll-off indicator: LED
provided (UF).
19) Overexcitation indicator: LED provided
(OE).
20) Protection on the devices: suitable R-C
snubber to be provided for the device used
to protect against voltage surges.
21) Dimensions:
- Overall: 105 x 96 x 38 (in mm)
- Mounting: 83 (in mm)
- Mounting hole dia: 6 (in mm)
22) Weight: 185 g.

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T7
T10
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T2
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T11
T3
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Installation and maintenance
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4 - MAIN FUNCTION OF THE AVR
The AVR is powered 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 identication)
Exciter eld
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
redblack
Armature
Varistor

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The AVR builds up the generator voltage
from its residual voltage to rated voltage.
When the generator is loaded, the sensed
voltage decreases and generates an error
signal, which is required in order for the
closed loop system to work.
Depending upon the value of the amplied
voltage, the ramp intersects the amplied
voltage at a point which is early or late in the
half-cycle.
At this intersection point, a starting pulse is
produced to trigger the power device.
Only qualied personnel should replace/
work on the AVR.
Do not increase the voltage beyond the
rated voltage.
5 - AVR SETTINGS
5.1 - V - Voltage
This function is provided for setting the
voltage up to ±10% of rated voltage by
means of a single-turn potentiometer. Turn
the potentiometer clockwise to increase the
voltage and vice versa, once the rated
speed has been reached.
External voltage setting up to ±15% of rated
voltage with 2K potentiometer on terminals
R1 and R2.
5.2 - UF - Under frequency knee
point setting
This function is provided to protect the AC
generator from sustained low speed
operation through a potentiometer. The
AVR will reduce the voltage in proportion
with the speed below the dened 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 default setting is 48.5 Hz.
5.3 - S
This function is provided to stop voltage
hunting by means of a potentiometer. Turn
clockwise to increase stability (to stop
oscillation). Turning too far clockwise will
result in a sluggish response and possibly
also oscillations.
The factory default setting is slightly
higher than critical damping.
6 - AVR CONTROLS
No. Control Function Direction
1 V Sets the generator output
voltage Turn clockwise to increase output voltage
2 S Stops voltage hunting Turn clockwise to increase stability
3 UF Sets the Under frequency
knee point Turn anticlockwise to reduce the knee point
450 Hz/60 Hz
selection
Selects 50 Hz mode or 60 Hz
mode of operation 60 Hz operation is selected when kept open
Caution: Whenever the R121 AVR is used with low voltage 110 VAC generator (parallel
connection) for the rst time, the AVR should be started with Voltage pot V in the minimum
position (fully anticlockwise). The R121 AVR can generate high voltage because the
voltage range is from 110 VAC to 270 VAC.

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7 - TROUBLESHOOTING CHART
Symptom Cause Action
No voltage
build-up
Fuse blown Check and replace
Low residual voltage across U
and N terminals
If the generator’s residual voltage at rated speed
is less than 2.5 VAC (L-N), disconnect the AVR
and connect a 24 VDC battery, keeping F1 as
positive and F2 as negative.
Connecting a freewheel diode (BY 127 or
equivalent) across the eld with the diode cathode
to F1 and the anode to F2 during eld ashing will
help restore the residual voltage.
WARNING:
Remove the diode (BY-127) after eld ashing.
The 24 V battery positive terminal must only be
connected to F1 and the negative to F2.
Swapping the connection will cause diode BY127
to explode instantly.
Incorrect wiring Check wiring
Rotating diodes and/or 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 eld 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 and correct
AVR defective Replace the AVR
Voltage oscillation Incorrect stability
potentiometer sealing
Turn clockwise until hunting stops
Prime mover speed hunting Check and adjust the controller
Load hunting, uctuates
rapidly
Check and correct
High percentage of non-linear
loads
Check and reduce the non-linear load
High reactance in generator
(during non-linear loading)
Consult the generator manufacturer
Incorrect
regulation
The exciter eld’s requirement
is too high
Wrong selection or very low P.F. load.
Check and correct.
Prime mover speed drops too
much when on load (kW load)
Adjust the controller and reduce the active load

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8 - MULTIMETER CHECKS
Equipment: Digital multimeter
Select Diode mode on the digital multimeter.
The resistance between F1 and F2 (with the
multimeter jack common applied to F1 of the
AVR) should be between 0.4 and 0.6 V, and
vice versa (with the multimeter jack common
applied to F2 of the AVR) should give
INFINITY.
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
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.

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R121
V
DC
V
DC
V
AC
Installation and maintenance
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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”inthe fully anticlockwiseposition.
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 difcult 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

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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
SUF OE UF

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Our technical support service will be
pleased to provide any additional
information you may require.
For all spare parts orders or technical
support requests, send your request to
[e-mail] or your
closest contact, whom you will nd 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
Description Type Code
AVR R121 5107292
11.2 - Technical support service

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Disposal and recycling instructions
We are committed limiting the
environmental impact of our activity. We
continuously monitor our production
processes, material sourcing and products
design to improve recyclability and minimise
our environmental footprint.
These instructions are for information
purposes only. It is the user’s responsibility
to comply 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-conductors.
- diode bridge (343) and surge suppressor
(347), found on the alternator rotor.
- major plastic components, such as the
terminal box structure on some products.
These components are usually marked with
information concerning the type of plastic.

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[e-mail] www.lrsm.co/support
Design
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contracts
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•Genuine spare parts
•Repair services
Our worldwide service network of over 80 facilities is at your service.
This local presence is our guarantee for fast and efcient repair, support and
maintenance services.
Trust your alternator maintenance and support to electric power generation experts.
Our eld personnel are 100% qualied 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:
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