Power-Tronics Professional Series User manual

© 2020 Power-Tronics, Inc.
XR8
Professional Series
Universal Voltage Regulator
REVISION A (or later)
The Power-Tronics XR8 Universal Voltage
Regulator is the latest upgrade for all UVR and
XR series voltage regulators and features an
upgraded regulation system and a higher
amperage rectifier section capable of 8 amps!
The XR8 is also capable of replacing other
manufacturers' voltage regulators and has
optional Static Exciter Modules to boost its
capacity to 30 amps DC!
The XR8 is designed specifically for Professional
Electrical Generator Service Technicians and
the Electrical Generator Repair Industry. It
incorporates an easily selectable frequency
range for voltage roll-off during under-frequency
operation and offers precise voltage regulation
regardless of the connected load and ambient
temperature. The XR8 is a ruggedized design
and is engineered to provide a lifetime of
trouble-free, reliable operation.
Manual stability matching is a thing of the past,
the XR8 contains patented electronic circuitry
that automatically matches the regulator's
response time to the generator exciter. This
greatly speeds installation and eliminates
guesswork.
PLC and automated Genset control is possible
with the XR8 by simply adding an optional,
inexpensive digital interface module. This
capability makes the XR8 suitable for automated
or unattended installations, or large-scale
parallel operations.
Like our previous models, the XR8 is fully
repairable! All major electronic components are
not encapsulated to facilitate repair while all
sensitive components are encapsulated to
protect them from contamination and moisture.
The XR8 is compatible with all previous and
current optional modules available for use with
Power-Tronics voltage regulators making it
extremely simple to upgrade an existing voltage
regulator installation.
Specifications
Input Voltage: 120 / 208 or 240vac
Frequency: 50 or 60hz
Voltage Regulation: ± .25% From NL to FL
Parallel Operation Yes
Maximum Output Voltage: 52vdc @ 120vac input
105vdc @ 240vac input
210vdc @ 240vac input
Continuous Output Voltage: 32vdc @ 120vac input
63vdc @ 240vac input
125vdc @ 240vac input
Maximum Continuous Output: 8adc
Minimum Field Resistance: 6.5Ω @ 32vdc output
13Ω @ 63vdc output
26Ω @ 125vdc output
Min Residual Build up Voltage: 3.5vac
Under Frequency Protection: Yes, VPH reduction
Physical Size: 4.75 x 6 x 1 in.
Weight: 7 oz
Repairable: Yes
Internal Protection: Fuses, cartridge type
External Voltage Adjustment: Yes
System Operating Indicator: Yes
Optional Static Exciter Modules: Yes
Optional External Controls: Yes
Cartridge Fuse Type: 3AG 10A @ 250V Fast-Blow
Optional External Potentiometer: 100KΩ @ 2W
External Adjustment Range: ±10% of Terminal Voltage

2
Table of Contents
Introduction and Functional Description:....................................................................3
Determining Which Hookup Configuration to Use:....................................................4
Common 12-Lead Generator Wiring Diagrams:..........................................................6
Use with PMGs, DPE, AUX, and Harmonic Winding Generators:..............................7
Hookup Connection A:...................................................................................................8
Parallel Configuration for Connection A:.....................................................................9
Hookup Connection B:.................................................................................................10
Parallel Configuration for Connection B:...................................................................11
Hookup Connection C:.................................................................................................12
Parallel Configuration for Connection C:...................................................................13
Initial Setup and Commissioning:...............................................................................14
Optional Power-Tronics Add-On Modules:................................................................15
Conversion From Shunt-Wound to Solid-State Regulation:....................................16
Internal Fuse Replacement:.........................................................................................17
Application Troubleshooting:......................................................................................18
Bench Check Procedures:...........................................................................................19
Installation Warranty Form:.........................................................................................20
Product Warranty Certificate:......................................................................................21

3
Introduction and Functional Description
Caution: Read This Installation Manual
Carefully and Entirely!
Warning: Do not use digital equipment to read voltage, Hz, or amperage during this
installation. Use only Analog sensing equipment! Failure to do so may result in damage to
equipment or in personal injury!
ALWAYS perform all setup procedures off-line
ALWAYS wear eye protection
ALWAYS strip wire insulation properly or use insulated connectors
ALWAYS use analog metering equipment when setting up the regulator
ALWAYS ensure the regulator receives ample airflow
NEVER hold the regulator in your hand when energized
NEVER install the regulator in a place it can get wet or is exposed to the elements
NEVER mount the regulator over a screw, bolt, rivet, welding seam, or other fastener
NEVER remove the regulator cover while the unit is in operation
NEVER insert a screwdriver or other object under the regulator cover
NEVER install a switch in the DC portion of the regulator’s wiring
NEVER USE A DIGITAL FREQUENCY METER (It can give a false reading!)
Functional Description
The XR8 Universal Voltage Regulator is the result of over 25 years of engineering efforts and offers high-demand features at a
competitive price point. The XR8 is a proven design and is engineered to greatly simplify setup while offering extreme reliability
in demanding service conditions. When properly installed, the XR8 Universal Voltage Regulator is designed to provide a lifetime
of service.
A Generator voltage regulator has several automated tasks it must perform in order to provide reliable, clean, and regulated
electricity. It must build-up the generator, regulate the terminal voltage within its design specifications, and protect both itself
and the generator should a fault situation arise.
The XR8 contains a time-proven, extremely reliable circuit for build-up functionality, in use for over 25 years. Due to its
simplicity, the XR8 is able to build up generators with residual voltages from 3.5VAC without initial overshoot or excessive delay.
The patented circuitry contained in the XR8 automatically adjusts the regulator to match the generator’s response time,
minimizing setup complexity while maximizing load acceptance and rejection performance. The XR8 is a precision voltage
regulator and is capable of regulating the terminal voltage of the generator within +/-.25% of its initial set point.
The XR8 uses field-replaceable 3AG ceramic cartridge fuses to protect its internal circuitry should a fault occur and the exciter
field current exceeds what the regulator is capable of delivering. It also contains a unique frequency-selectable Volts-Per-Hertz
circuit, which helps a turbo-charged engine accept a large load, and also helps to protect the generator rotor and exciter if the
engine is idled with the regulator still energized.
Due to its extreme simplicity, the XR8 Universal Voltage Regulator is uncommonly reliable and offers features and regulation
accuracy usually only offered by much more complicated and often much more expensive regulators.

4
Determining Which Hookup Configuration to Use
STOP! If you are using an optional SEM250A/B or SE350/450 Static Exciter
Module, DO NOT use these instructions for hookup! See the instructions that
came with your module instead!
The XR8 Universal Voltage Regulator is configurable for 3 different output ranges suitable for use on the vast
majority of generators available on the market from past and present. It is necessary to choose the proper
mode of operation for your generator in order to get the best regulation and fastest response time possible.
To determine the proper connection for your generator you need to know any two of the following 3
specifications from the rating plate of your generator:
1: Exciter Field Voltage (in DC Volts) [Generally given in full load Voltage on nameplates]
2: Exciter Field Resistance (in Ohms) [See Note Below]
3: Exciter Field Amperage (in DC Amps) [Generally given in full load Amps on nameplates]
Using the specifications obtained from your generator exciter, select a
Connection (A, B, or C) from the chart below:
• Exciter Field Resistance ≥26Ω & Exciter Full-Load Voltage ≤125VDC
Use connection A (See Page 8)
• Exciter Field Resistance ≥13Ω & Exciter Full-Load Voltage ≤63VDC
Use connection B (See Page 10)
• Exciter Field Resistance ≥6.5Ω & Exciter Full-Load Voltage ≤32VDC
Use connection C (See Page 12)
Note about Field Resistance:
• When measuring field resistance on a brushless generator, simply measure the resistance of the exciter field
through your field leads with a multimeter.
• When measuring field resistance on a brush-type generator, measure the resistance through both the field
leads as well as directly on the slip rings themselves. The readings you obtain should ideally be the same,
but no more than 1% difference. If you show more than 1% difference in reading your generator has brush
and ring contact problems and will need cleaning or maintenance before installing the XR8. Failure to correct
brush and ring contact problems will result in severe damage to the voltage regulator as well as
possible PERMANENT damage to the slip rings themselves! NEVER use emery cloth, carborundum
stones, “comm sticks”, or Tuner cleaner to dress or clean slip rings. They will make a bad problem
much, much worse! Only use Garnet or Flint sandpaper and clean with a clean rag soaked with Acetone for
best results!

5
If you do not have any of the specifications of your generator’s exciter, or if you
don’t know where to start when trying to determine your exciter specs, please
see the section below for instructions on measuring and calculating your exciter
specifications.
• Measure your exciter field resistance using a multimeter on your field leads. Record this value. If
you have a brush-type generator, also take a resistance reading on your slip rings: the value you
obtain on the slip rings should be no more than 1% difference from the value you obtained through
the field leads.
• Next, start and run the generator and apply 12V from a battery through your field leads and record
the AC voltage produced by the generator. To determine your full load exciter field voltage, use
the following formula:
EExc. =
Where EGen.Conf. is your Generator’s configured voltage (e.g.: 120, 208, 240, 480V, etc.), EGen.Output is
your recorded output voltage, and EBattery is your battery voltage (12V usually).
• Next, calculate your maximum exciter field amperage using your measured field resistance and
your calculated exciter voltage using the following formula:
Where I is your maximum exciter field current, E is your calculated field voltage from the above
formula, and R is your measured field resistance.
Using the values you just measured and calculated, see the chart on the
previous page to determine which connection you should use to connect the
XR8 to your generator.
For Example:
Measured Field Resistance: 18Ω
Battery Voltage: 12V
Generator Configuration: 480V Wye
12V applied to the field yields 189VAC L1-L3.
EExc. =
480
$%&
$'
∗ 2 = 60.95
EExc. = 60.95VDC (Full-Load Voltage)
This generator would use Connection B.
€
EGen.Conf .
EGen.Output
EBattery
"
#
$
$
%
&
'
'
* 2
I=E
R

6
Common 12-Lead Generator Wiring Diagrams
Series Wye (416/480V 3ø)
Voltage L-L: 416/480V
Voltage L-N: 240/277V
Voltage CT – N: 120/139V
Parallel Wye (208/240V 3ø)
Voltage L-L: 208/240V
Voltage L-N: 120/139V
NOTE: 208V is Standard Voltage
Series Delta (240V 3ø)
Voltage L-L: 240V
Voltage L1/L2-N: 120V
Voltage L3 – N: 208V
NOTE: L3-N is a “High Leg”
208V instead of 120V!
Double-Delta (120/240V 1ø)
Voltage L-L: 240V
Voltage L-N: 120V
Preferred Single-Phase Connection.
Don’t Use Zig-Zag if Possible.
NOTE: Derate generator by 1/3 rated
capacity when using this connection!

7
PMG, DPE Winding, Auxiliary Winding, and
Harmonic/Resonant Winding Use
The XR8 Universal Voltage Regulator is compatible with some of these types of generators but
not others. It is necessary to determine which type of generator you have before proceeding
since some styles will connect differently than others while the XR8 cannot be used with some
of these generators at all.
PMG (Permanent Magnet Generator/Exciter):
This type of generator generally has a permanent magnet generator mounted on the main shaft along
with a brushless exciter and finally the main rotor itself. The XR8 is a very fast responding regulator
(1/2 cycle response time) and low enough burden on the main stator that it can be used on these
generators without any need for the PMG input.
To connect the XR8 to this type of generator, isolate and insulate the PMG leads that were connected
to the original voltage regulator. Measure your field resistance and proceed with sizing on Page 4.
DPE Winding and Auxiliary Winding:
These generators use an extra winding in the main stator as a power supply for the voltage regulator
in an attempt to give the regulator a clean power source that isn’t affected by load. The XR8 has
proprietary filtering circuitry in its sensing stage that is largely unaffected by generator load. Because
the regulator isn’t affected by loading, these types of windings are not needed.
To connect the XR8 to this type of generator identify, isolate, and insulate the Auxiliary or DPE wiring
that were connected to the original voltage regulator. Measure your field resistance and proceed with
sizing on Page 4.
Harmonic and Resonant Windings:
This type of generator rarely has a voltage regulator, and instead relies on a phase-shifted “harmonic”
winding and a capacitor to adjust the terminal voltage with load. They often have a brushless
“exciter”, but because they operate on harmonics from the AC waveform, they do not operate like a
typical brushless exciter.
Because these generators rely on AC waveform
phasing for their voltage regulation, the XR8
cannot be used with this type of generator.

8
Connection A
(See page 9 if the generator will be paralleled using this connection)
Connection A is a Full-Wave rectified configuration, which allows a continuous output of 125VDC @
8A with an input voltage of 240VAC.
This connection is typically used on higher voltage excitation fields (generally referred to as 125V
fields) or on shunt control fields where the full-load excitation voltage is greater than 63VDC.
Note that the maximum input voltage to the XR8 Universal Voltage regulator is 240VAC!
DO NOT input 277VAC into the XR8! Severe damage to the unit will result! For use on 480V
systems, either connect the regulator to the winding center taps T7 and T9 (See Page 6) or use a
480-240V step-down transformer rated at 1.5KVA.
Connecting the input of the XR8 to 2 different legs of the generator as shown in the diagram below
will result in greater regulation accuracy than when connecting line-neutral.
NOTE:
It is not necessary
to jumper terminals
7 and 8 if not using
the Remote Voltage
Adjustment!
XR8 Professional Series
Universal Voltage Regulator
NOTE:
If the generator is to be operated below 50/60 Hz, a disconnect or switch should be installed in series
with the incoming power to terminals #1 and #2 on the XR8.
NEVER install a switch or breaker on the DC or Exciter side of the voltage regulator!
Only install a switch or disconnect on the AC Side of the regulator!
240VAC
MAX!
100K, 2W
Regulator On/Off
Switch
Rate for:
240V @ 10A

9
Parallel Configuration for Connection A
To use the XR8 Universal Voltage Regulator in a parallel configuration either with another generator
or with a buss such as a utility, use the diagram below for proper hookup with the XR8 configured for
Connection A.
NOTE: Power-Tronics products parallel using the Reactive Droop compensation method. This allows our products to
parallel with existing systems easily while also allowing islanded operation with the flip of a switch. When initially installing
the droop resistor, set it for approximately 7Ω before final adjustment later. If the droop is excessive when load testing,
reduce the resistance a bit at a time until satisfactory droop is achieved.
CT should be sized at 25-35VA burden!
XR8 Professional Series
Universal Voltage Regulator
240VAC
MAX
Secondary
Voltage!
100K, 2W
Unit/Parallel
Switch
Reactive Droop
Adjustment
10Ω, 100W
CT Rating:
XXX/5A @ 25-35VA
Transformer
Rating:
XXX:240V
@ 1.5KVA
Regulator On/Off
Switch
Rate for:
Primary Voltage
@ 10A
Setup Tips:
•Isolation Transformer is
recommended for best
results, but is optional if
208/240V is present on
generator.
•Size CT as closely to rated
generator output amperage
as possible for best
paralleling results. An
oversized CT will result in
poor paralleling or loss of
control!
•If generator terminal voltage
rises, or if generator exports
VARS excessively under
load, reverse CT leads.
•If the reactive droop
resistor/rheostat gives
erratic results or
inconsistent resistance,
lightly sand the exposed
wire with 400 grit sandpaper
to improve connection
between wire and slider.

10
Connection B
(See page 11 if the generator will be paralleled using this connection)
Connection B is a Half-Wave rectified configuration, which allows a continuous output of 63VDC @
8A with an input voltage of 240VAC.
This connection is typically used on a majority of brushless generator excitation fields (generally
referred to as 63V fields) or on shunt control fields where the full-load excitation voltage is greater
than 32VDC, but less than or equal to 63VDC.
Note that the maximum input voltage to the XR8 Universal Voltage regulator is 240VAC!
DO NOT input 277VAC into the XR8! Severe damage to the unit will result! For use on 480V
systems, either connect the regulator to the winding center taps T7 and T9 (See Page 6) or use a
480-240V step-down transformer rated at 1KVA.
Connecting the input of the XR8 to 2 different legs of the generator as shown in the diagram below
will result in greater regulation accuracy than when connecting line-neutral.
NOTE:
It is not necessary
to jumper terminals
7 and 8 if not using
the Remote Voltage
Adjustment!
XR8 Professional Series
Universal Voltage Regulator
NOTE:
If the generator is to be operated below 50/60 Hz, a disconnect or switch should be installed in series
with the incoming power to terminals #1 and #2 on the XR8.
NEVER install a switch or breaker on the DC or Exciter side of the voltage regulator!
Only install a switch or disconnect on the AC Side of the regulator!
240VAC
MAX!
100K, 2W
Regulator On/Off
Switch
Rate for:
240V @ 10A

11
Parallel Configuration for Connection B
To use the XR8 Universal Voltage Regulator in a parallel configuration either with another generator
or with a buss such as a utility, use the diagram below for proper hookup with the XR8 configured for
Connection B.
NOTE: Power-Tronics products parallel using the Reactive Droop compensation method. This allows our products to
parallel with existing systems easily while also allowing islanded operation with the flip of a switch. When initially installing
the droop resistor, set it for approximately 7Ω before final adjustment later. If the droop is excessive when load testing,
reduce the resistance a bit at a time until satisfactory droop is achieved.
CT should be sized at 25-35VA burden!
XR8 Professional Series
Universal Voltage Regulator
240VAC
MAX
Secondary
Voltage!
100K, 2W
Unit/Parallel
Switch
Reactive Droop
Adjustment
10Ω, 100W
CT Rating:
XXX/5A @ 25-35VA
Transformer
Rating:
XXX:240V
@ 1KVA
Regulator On/Off
Switch
Rate for:
Primary Voltage
@ 10A
Setup Tips:
•Isolation Transformer is
recommended for best
results, but is optional if
208/240V is present on
generator.
•Size CT as closely to rated
generator output amperage
as possible for best
paralleling results. An
oversized CT will result in
poor paralleling or loss of
control!
•If generator terminal voltage
rises, or if generator exports
VARS excessively under
load, reverse CT leads.
•If the reactive droop
resistor/rheostat gives
erratic results or
inconsistent resistance,
lightly sand the exposed
wire with 400 grit sandpaper
to improve connection
between wire and slider.

12
Connection C
(See page 13 if the generator will be paralleled using this connection)
Connection C is a Half-Wave rectified configuration, which allows a continuous output of 32VDC @
8A with an input voltage of 120VAC.
This connection is typically used on low voltage excitation fields (generally referred to as 32V fields)
or on shunt control fields where the full-load excitation voltage is less than 32VDC.
Note that the maximum input voltage to the XR8 Universal Voltage regulator is 139VAC in this
configuration! DO NOT input 240VAC into the XR8! Severe regulation problems may result! For
use on 480V systems, either connect the regulator to the winding center taps T7 to T0 (See Page 6)
or use a 480-120V step-down transformer rated at 500VA (Preferred for superior regulation
accuracy).
Connecting the input of the XR8 to 2 different legs of the generator through a transformer will result in
greater regulation accuracy than when connecting line-neutral as shown in the diagram below.
NOTE:
It is not necessary
to jumper terminals
7 and 8 if not using
the Remote Voltage
Adjustment!
XR8 Professional Series
Universal Voltage Regulator
NOTE:
If the generator is to be operated below 50/60 Hz, a disconnect or switch should be installed in
series with the incoming power to terminals #1 and #2 on the XR8.
NEVER install a switch or breaker on the DC or Exciter side of the voltage regulator!
Only install a switch or disconnect on the AC Side of the regulator!
139VAC
MAX!
100K, 2W
Regulator On/Off
Switch
Rate for:
240V @ 10A

13
Parallel Configuration for Connection C
To use the XR8 Universal Voltage Regulator in a parallel configuration either with another generator
or with a buss such as a utility, use the diagram below for proper hookup with the XR8 configured for
Connection C.
NOTE: Power-Tronics products parallel using the Reactive Droop compensation method. This allows our products to
parallel with existing systems easily while also allowing islanded operation with the flip of a switch. When initially installing
the droop resistor, set it for approximately 7Ω before final adjustment later. If the droop is excessive when load testing,
reduce the resistance a bit at a time until satisfactory droop is achieved.
CT should be sized at 25-35VA burden!
XR8 Professional Series
Universal Voltage Regulator
120VAC
MAX
Secondary
Voltage!
100K, 2W
Unit/Parallel
Switch
Reactive Droop
Adjustment
10Ω, 100W
CT Rating:
XXX/5A @ 25-35VA
Transformer
Rating:
XXX:120V
@ 500VA
Regulator On/Off
Switch
Rate for:
Primary Voltage
@ 10A
Setup Tips:
•Isolation Transformer is
recommended for best
results even if 120/139V is
present on generator.
•Size CT as closely to rated
generator output amperage
as possible for best
paralleling results. An
oversized CT will result in
poor paralleling or loss of
control!
•If generator terminal voltage
rises, or if generator exports
VARS excessively under
load, reverse CT leads.
•If the reactive droop
resistor/rheostat gives
erratic results or
inconsistent resistance,
lightly sand the exposed
wire with 400 grit sandpaper
to improve connection
between wire and slider.

14
Initial Setup and Commissioning
1. Install the regulator and wire according to the correct wiring
diagram (Connection A, B, or C).
2. If installing the XR8 on a brush-type generator, verify that the
brushes and brush riggings are isolated, ungrounded, and
connected ONLY to the XR8.
3. Turn the internal voltage control 15 or more turns counter
clockwise (left) or until you hear the screw click. This procedure is
necessary in case the original factory settings have been altered.
4. If you are using a remote voltage adjustment, set it at 50% of
adjustment.
5. If the generator is to be paralleled, set the droop resistor between
6Ω and 10Ω.
6. Start up the prime mover and bring up to operating speed and turn
on the regulator switch (if used).
7. Set the internal voltage adjustment to the desired voltage setting
for the generator output by turning the adjustment screw
clockwise (right).
The voltage adjustment is a 25-turn pot!
NOTE: The maximum internal voltage setpoint is 260VAC! This helps
prevent accidental over-voltage conditions due to incorrect installation!
8. Place the generator on line and observe the frequency and voltage.
9. If the generator is being paralleled, measure the droop during loading and adjust the droop resistor as
necessary. Reducing droop resistor resistance will reduce droop.
NOTE: Loading the generator with a purely resistive load-bank may cause undesirable droop
characteristics such as no droop, very slight droop, or even rising terminal voltage. Measure droop
with a mixed load for best results.
10. If paralleling and the terminal voltage rises or excessive amperage exportation occurs during loading with a
mixed load connected, reverse the CT leads and try again.
11. Observe voltage regulation during no-load and full-load conditions. Once the voltage is set and regulating
characteristics are satisfactory the installation procedure is complete.
Voltage
Adjustment
(25 Turn!)
Status Lamp
50/60Hz FF
Selection
REMOVE
JUMPER
for 50Hz!

15
Optional Power-Tronics Add-On Modules
Power-Tronics offers a wide array of optional add-on modules for the XR series voltage
regulators from static exciter modules to digital interface cards. For more information on any
of the modules below, visit our online catalog at:
www.power-tronics.com
SEM250A
Static Exciter Module
Converts the XR8 into a 63VDC
25ADC Static Exciter!
SEM250B
Static Exciter Module
Converts the XR8 into a
125VDC 25ADC Static Exciter!
AFM5X
Automatic Flash Module
Adds Automatic Flash or
Battery Flash to installations
with low residual or requiring
guaranteed buildup!
EIC1020
External Interface Card
Allows the XR8 to be controlled
externally by virtually any digital
load-sharing controller, VAR
controller, genset controller, or
digital governor controller!
MOP1224HD
Motorized Potentiometer
Allows the XR8 to be externally
controlled by older automated
controllers using pulsed signals
or dry contacts for control!
HVD2
High Voltage Disconnect
Adds passive protection for
your generator and connected
equipment from runaway and
high voltage conditions!
Disconnects power to the

16
Conversion From Older Shunt-Wound Voltage
Regulation to Modern Solid-State Voltage Regulation
It is possible to use the XR8 Universal Voltage regulator with older Shunt-Wound exciters that
originally had manual, mechanical, or series solid-state voltage regulators by converting the wiring as
in the diagrams below. If the generator will not build up after conversion, try switching your F+ and F-
leads at the regulator and try starting up again.
NOTE:
Armature brushes
MUST BE ISOLATED
from the field leads for
proper operation!

17
Fuse Replacement
The XR8 contains two 32mm 3AG cartridge fuses located for quick and convenient replacement
should they blow. To replace the fuses, follow the instructions below.
Fuse size is 32mm x 6.3mm rated at 10A at 250VAC.
Power-Tronics Part Number: 5R3-626 (Comes as a package of 10 fuses)
Cooper-Bussmann Part Number: BK/ABC-10 or BK/ABC-10R
Littelfuse Part Number: 0314010.MXP or 0314010.HXP
Fuse Replacement Procedure:
(Refer to the image above for easy reference)
• Remove the 4 screws located on the front of the aluminum mounting can to allow removal of the
can.
• Remove the aluminum mounting can from the circuit card.
• Use a continuity tester or multimeter to test the fuses (A good fuse will read continuity or 0Ω
resistance)
• Replace open fuses then replace and re-tighten all screws.
• Fuse size is 32mm x 6.3mm, 10A @ 250VAC. (DO NOT REPLACE WITH ANY OTHER TYPE
OR RATING OF FUSE! YOU WILL VOID YOUR WARRANTY AND SEVERE DAMAGE AND
PERSONAL INJURY COULD RESULT BY DOING SO!)
Fuse Locations

18
Application Troubleshooting
Problem: Possible Cause
No Voltage 1 3 5 7 9 11 13 15 20
Pulsating Voltage 4 5 6 12 16
Flickering Voltage 4 6 7 14
High Voltage 6 7 8 9 12 13 17 18 20
Voltage Drop on Load 5 8 10 12 16
Low Voltage 5 8 12 13
Poor Voltage Regulation 2 4 10 12 13 16
No Voltage Control 13 19 20
Possible Causes:
1. Residual input voltage to the voltage regulator is below 3.5vac or fuses are open in the regulator.
2. Unbalanced generator load.
3. Open exciter field or defective generator.
4. Non linear (Inverter) load or defective connection in exciter field.
5. Open diode in exciter or shorted rotor in generator.
6. Loose component in voltage regulator.
7. Loose wiring connections.
8. Input voltage to regulator is too low.
9. Exciter field is grounded.
10. Non linear (Inverter) load or wrong selection for regulator hookup.
11. Exciter fields are reversed.
12. Wrong selection of regulator wiring configuration.
13. Defective voltage regulator.
14. SCR or Inverter drive effecting generator waveform.
15. Regulator needs external flashing circuit.
16. Isolation transformer is too small.
17. Isolation transformer is needed.
18. Exciter fields are not isolated from other circuits.
19. Input and field circuit are being fed by a common cable or conduit.
20. Incorrect hookup or wiring.

19
Bench Check Procedures
1. Wire the regulator as shown in Figure A below.
2. Connect a 120 volt 50 to 150 watt light bulb as shown.
3. Adjust the internal voltage pot fully CCW (25 turns) or until a click is heard.
4. Input 120vac into the regulator at #1 and #2. (Fuse this input with fuses rated at 120 volts or higher and not more
than 5 amps)
5. Observation: The green status light should be on and the incandescent light bulb should be off. If the green status
light is not on, the internal fuses are blown in the regulator or there is internal damage to the regulator! If the green
status light is not on, do not continue this test!
6. SLOWLY turn the internal voltage adjustment CW until the incandescent light bulb turns fully on, then adjust the
internal voltage adjustment CCW until the light bulb is off.
7. Observation: You should be able to taper the incandescent light bulb on and off in a relatively smooth manner. If
the light flashes on or off quickly, the regulator has an internal fault, do not continue this test!
8. Remove the 120vac from the regulator.
9. Reconnect the regulator as shown in Figure B and perform all of the previous steps again. In this mode, the light
bulb will only glow at half brightness!
10. If you were able to successfully perform all of these tests, the regulator is good. IF ANY SINGLE STEP
FAILED, THE REGULATOR IS DEFECTIVE!
Figure A
120V 50-150W
Incandescent
Figure B
120VAC
Fused
@ 5A
120V 50-150W
Incandescent
120VAC
Fused
@ 5A

20
Installation Warranty Form
It is very important that you fill out this form completely when installing a voltage regulator. This form
serves as a history record on the application. This form also contains the information needed by
Power-Tronics, Inc., for repair and troubleshooting of any product you may be having problems with.
Failure to fill out this form during installation will result in a cancellation of your warranty
coverage! Filling out this form takes only minutes but will save hours or days later on if your
product should require service!
Problem Description/History (Please be detailed!!!):
Ship-To Address (City, State, Zip, Country):
Company Name:
Contact Person:
Telephone Number:
Email Address:
Primary Load (Please Explain):
Repair/Warranty Request Information
Generator Leads (Check One:) ☐12 ☐10 ☐6 ☐4 (3ø) ☐4 (1ø) ☐3
Generator Wiring Mode (Check One:) ☐High-Wye ☐Low-Wye ☐Series Delta
☐Zig-Zag ☐Double-Delta ☐Single-Phase ☐Other
Terminal Voltage:
Residual AC Voltage:
Rated KW:
Rated KVA:
Generator Wiring/Usage Information
This Section for Brushless Generators Only
Exciter Field Voltage:
Exciter Field Resistance:
This Section for Brush-Type Generators Only
Shunt-Field Voltage:
Shunt-Field Resistance:
Rotor Resistance @ Brush Leads:
Rotor Resistance on Slip-Rings:
Rotor Excitation Voltage:
Product Model:
Serial #:
Date of Installation:
Additional Module(s) or Options: