Avtron LPH400 User manual

AVTRON MODEL LPH400
RESISTIVE LOAD BANK
Part Number LPH400D43233
©2008 AVTRON • Cleveland, Ohio January 30, 2008
Rev. February 11, 2008

AVTRON
Cleveland, Ohio
AVTRON MODEL LPH400
RESISTIVE LOAD BANK
Part Number LPH400D43233
TABLE OF CONTENTS
Section Page
I SAFETY CONSIDERATIONS........................................................................... 1-1
II DESCRIPTION.................................................................................................... 2-1
III INSTALLATION ................................................................................................ 3-1
IV OPERATION....................................................................................................... 4-1
V MAINTENANCE ................................................................................................ 5-1
VI REPLACEMENT PARTS LIST.......................................................................... 6-1
APPENDIX - Avtron Load Bank Troubleshooting Guide
DRAWINGS
SB2975 Outline Drawing
D43234 Schematic, Load Bank
D27552 Resistor Assembly
D27553 Resistor Assembly
D27555 Resistor Assembly
SUPPLEMENTAL VENDOR MANUALS (Provided Separately)
Electro Industries/ SHARK100 Installation and Operation Manual — CD/ROM,
Gauge Tech E145420
Electro Industries/ Quick Start Guide for SHARK Series Meters, E145703
Gauge Tech
-i-

1-1
AVTRON MODEL LPH400
RESISTIVE LOAD BANK
Part Number LPH400D43233
SECTION I
SAFETY CONSIDERATIONS
Throughout this manual, you will find WARNING and CAUTION statements. Personal injury
or death may occur to an operator using or repairing the equipment if a WARNING statement is
ignored. Damage to the equipment and potentially hazardous conditions for personnel may
occur if a CAUTION statement is ignored.
Each Avtron unit is safety checked for opens and shorts, and the insulation is high potential
tested to ensure safe operation. All fuses, safety interlocks and related safety equipment have
been tested as part of the testing procedure of each unit.
As part of your safety program, an initial inspection after receiving the unit(s) and periodic
preventive maintenance and safety inspections should be conducted to ensure the reliability and
safety built into your Avtron equipment.
The Model LPH400 Load Banks are industrial test units designed for safe use indoors.
However, because the Load Bank’s function is to dissipate electrical energy, there are inherent
dangers to the operators and to the equipment. These dangers shall be outlined in this section.
Electrical energy is transformed into heat by the resistors. This heat must be removed from the
Load Bank by the cooling fan. If there is any restriction or stoppage of airflow, the Load Bank
may overheat and may even start a fire. The following events must be conducted if safe
operation of the Load Bank is to take place.
1. Read the manual before operating Load Bank.
2. An approved ground conductor wire from the Load Bank ground point and the generator
frame to a good earth ground must be connected.
3. Do not bypass the airflow switch to prevent nuisance tripping. The switch is designed to
drop out the load if sufficient air is not reaching the load elements.
4. Do not bypass any fuses which have blown. Bypassing fuses can result in damage to the

Safety Considerations Avtron Model LPH 400 • Resistive Load Bank
Part Number LPH400D43233
1-2
equipment and potentially hazardous conditions for the operator. If a fuse is blown,
determine the cause of the blown fuse and correct the situation.
5. Replace any burned out bulbs on the Control Panel. Each lamp is an indication that a
system is active or has failed and is important to the operation of the Load Bank and
safety of the operator.
6. Maintenance personnel must always exercise caution when access panels are removed.
Personal injury from electrical shock or from the moving fan blade may result if all
sources of power are not disconnected before servicing. Maintenance work must be
conducted only by qualified personnel.
7. The Load Bank should be operated in a cool, well ventilated area as described in the
INSTALLATION section of this manual. Do not allow exhaust air to recirculate through
the Load Bank.
8. Venting the heated air from the Load Bank exhaust is a potential hazard. The Load Bank
should be used in a cool, well ventilated area.
9. Allow cool air to pass into the unit to cool the elements. Do not allow the unit to be
placed where hot exhaust air can recirculate back through the unit causing a constant rise
in cooling air temperature.
10. After running a load test, residual heat should be removed from the Load Bank by
allowing the fan to operate for a few minutes after load is removed. This procedure is not
required for maintaining Load Bank integrity, but it may guard operating personnel from
possible burn injuries.
11. The operator should avoid coming in contact with the resistor elements or surrounding
covers during and for some time after operation. These portions of the Load Bank
become quite hot and may result in a serious burn, should contact be made with them.
12. Do not allow objects to enter or block the air intake or exhaust of the Load Bank. A
blockage could cause Load Bank overheating. If an object enters the screens, it will
cause damage to the resistor elements, possibly shorting them and causing shock and fire
hazards.
13. Operators must not operate the Load Bank with the access panels, cover, or screens
removed. To do so exposes the operator and other persons to possible personal injury
from electrical shock or from the moving fan blade.
14. Keep the hinged cover on the customer connection access box (Load Connection
Compartment) closed at all times during testing and while power is on the load bus.
15. Always put a short or shunt across the current transformers (C.T.) when working on
metering. Powering up an unshunted C.T. will destroy the C.T. with possible harm to

Safety Considerations Avtron Model LPH 400 • Resistive Load Bank
Part Number LPH400D43233
1-3
personnel and metering.
16. Emergency shutdown procedure:
A. In an emergency, shut down the MASTER LOAD switch, then the generator.
The MASTER LOAD switch will allow disconnection of all load steps and still
allow the fan motor to run, cooling any heated elements.
B. The power ON/OFF switch will disconnect both load steps and fan motor. A
customer-supplied Generator Emergency OFF switch should be located near the
Load Bank.
17. An approved electrical fire extinguisher should be on hand at all times.
18. It is the responsibility of the customer to take diligent care in installing the Load Bank.
The National Electrical Code (NEC), sound local electrical and safety codes, and the
Occupational Safety and Health Act (OSHA) should be followed when installing the
equipment to reduce hazards to persons and property.
19. Read and heed all WARNING and CAUTION statements in the manual.
20. Review supplemental metering manual prior to operation.

Description Avtron Model LPH 400 • Resistive Load Bank
Part Number LPH400D43233
2-1
SECTION II
DESCRIPTION
The Model LPH400 Load Bank is a portable, primarily indoor, self-contained unit for
electrically loading and testing generators. The Load Bank is rated at 400 kW at 240/480 volts.
The available load steps are 100 kW, 100 kW, 100 kW, 50 kW, 25 kW, 10 kW, 10 kW, and
5 kW. All load steps are selected by toggle switches. The Load Bank provides a balanced load
for 3-phase generators within the range listed above. Single phase loads are 2/3 the normal 3-
phase load. Do not run fan power from bus if single phase testing.
The fan motor is a 3 HP, 3-phase motor which operates from 208-230/460 volts, 3-phase, 60 Hz
power. The fan motor obtains power from either the power source under test (fan motor
connected to Load Bank main load bus) or from a remote source (external power source). When
operating from the power source under test, the motor circuit connects the motor for high or low
voltage. The unit will test 240/480 volt, 3-phase, 60 Hz generators without any wiring changes.
It can be used to test 60 Hz, 50 Hz, or 400 Hz generators; however, the fan motor and control
circuit power must be supplied by separate 60 Hz sources when testing 50 Hz or 400 Hz
generators. For separate 60 Hz fan motor power connection, see Section III. Control power is
115 VAC, 60 Hz and is provided by an integral 240/480V to 115V control transformer.
Fan failure protection is provided in two ways. A differential pneumatic pressure air switch
(S51) senses the airflow through the Load Bank. An additional slave relay (K30) is activated
only if power is applied to the fan motor terminals. This slave relay will disconnect control
power to all load contactors should the fan power be disconnected, the motor overload trip out,
or the air inlet screens become blocked.
*******************************************************
C A U T I O N
This Load Bank should never be used without the fan motor
operating. Inadequate cooling airflow will result in resistor
elements overheating and a definite fire hazard.
*******************************************************
GENERAL CONSTRUCTION (Refer to Outline Drawing SB2975.)

Description Avtron Model LPH 400 • Resistive Load Bank
Part Number LPH400D43233
2-2
The Control Panel is mounted in the Load Bank behind a sliding door. It is also sized for
mounting into a 19-inch rack enclosure. The control panel contains all the switches required to
operate the Load Bank. Full digital metering is standard and displays volts, amps, and kW with
individual phase selection. The Load Bank is constructed of aluminized steel, forming a rigid
structure. Mounted within this structure are the load element resistor assemblies, the cooling fan
and motor, the load step contactors, motor starter, motor overload relay, fuses and customer
connection load bus. The cooling air is drawn in from intake end (fan end) and both sides,
forced across the resistor elements and exhausted out the opposite end.
The unit is mounted on six-inch casters with one set provided with wheel locks. The customer
connection access box is located on the intake side of the unit. Load connection is made on the
intake end in the load connection compartment (Customer Connection Access Box).
The Load Bank can operate at either 480 or 240 volts. A switch on the control panel (S7) will
switch the load from the high voltage configuration to the low voltage configuration. The fan
motor configuration also changes if powered from generator under test. The fan motor has
separate overload protection for high and low voltage operation. The voltage protection circuit
will protect the circuit if improper voltage mode is applied. However, it is always best to
confirm source voltage, then match control panel switches to proper configuration before
energizing the unit.
Lower voltages and different frequencies may be applied to the load circuit of the Load Bank.
Frequency change causes no derating of the load; however, the applied kW with a lower voltage
is computed with the following formula:
)
RatedVoltage(
)
AppliedVoltage(
kW
=
kW 2
2
RatedApplied 
*******************************************************
C A U T I O N
Never exceed the rated voltage, because this will cause the Load
Bank to overheat. Do not apply DC voltages, because the
contactors do not have arc blowout magnets.
C A U T I O N
External fan power may be required if a voltage different from
240/480 is being applied or a frequency other than 60 Hz. (See
Section III for further details.)
*******************************************************

Installation Avtron Model LPH 400 • Resistive Load Bank
Part Number LPH400D43233
3-1
SECTION III
INSTALLATION
BEFORE INSTALLATION
Inspect the Load Bank for obvious damage such as broken wires, broken or dented panels,
cracked ceramic insulators, or any other component breakage that may have occurred in
shipment.
LOCATION
The Load Bank is designed primarily for indoor use. The Load Bank must be used in a cool,
well ventilated area. It must be installed where cool air is continually available and where hot
exhaust air will not be recirculated through the Load Bank. If the Load Bank is operated in a
closed space, ventilation of 11,000 CFM or greater is required.
Temporary outdoor use is acceptable if climate and environment are suitable. Some moisture
from light (non-freezing) rain will not damage the unit if running or in storage outdoors with
control panel slide cover door shut.
A minimum of four feet of clearance from the inlet end and eight feet of clearance on the exhaust
end are required for proper airflow.
*******************************************************
W A R N I N G
The exhaust air may be in excess of 250oF above ambient under
full load conditions. The unit must not be installed near any
equipment, wiring or plumbing which may be damaged by high air
temperatures or which may constitute a fire hazard. Care should
also be taken so as not to set off a sprinkler system by exposing it
to hot exhaust air.
*******************************************************

Installation Avtron Model LPH 400 • Resistive Load Bank
Part Number LPH400D43233
3-2
DO NOT STACK LOAD BANKS.
Standard Load Bank design is suitable for operation between sea level and 3,000 feet maximum
altitude.
AIRFLOW CONSIDERATIONS
Even with an ample supply of cooling air, the Load Bank may overheat, if it is not properly
installed. There are two types of airflow problems that should be avoided:
1. RECIRCULATING AIRFLOW - If the hot, exhausted air is permitted to recirculate
through the Load Bank, it will reach such a high temperature and low density that it will
no longer cool the resistance elements. Maximum allowable intake air temperature is
120F. A Load Bank should not be installed so close to any surface which may reflect
the exhausted air back to the air intake. When two or more Load Banks are being used,
care must be taken in positioning the Load Banks so that the exhausted air of one unit
does not feed the air intake of another.
2. RESTRICTION OF COOLING AIR - Any obstruction located within four (4) feet of the
inlet or eight (8) feet of exhaust screens will restrict the Load Bank's airflow. Airflow is
also restricted when two or more Load Banks have air inlets positioned close to each
other. This competition for cooling air causes a low pressure area, restricting adequate
airflow to either unit.
*******************************************************
W A R N I N G
It is vitally important to install the Load Bank properly.
Installation errors may result in a catastrophic failure. The Airflow
switch, a protective device in the Load Bank, will guard against
some of these problems. If protective circuitry prevents
application of the load, determine the source of the problem. DO
NOT DISABLE the AIRFLOW SWITCH. This will cause a safety
hazard and will void our warranty. The following installation
instructions are critical to the safe operation of the Load Bank.
(Refer to Section I, SAFETY CONSIDERATIONS, of this
manual.)
*******************************************************
3. The heated exhaust air stream can damage any temperature sensitive items if they are
positioned within 25 feet of exhaust air.

Installation Avtron Model LPH 400 • Resistive Load Bank
Part Number LPH400D43233
3-3
4. Load Banks mounted into a channel, trough, hollow, well, or pit, or exhausting into a full
wall or corner, require special considerations even if above conditions are met. In these
cases, provide a detailed sketch of site layout for Avtron to inspect and comment.
POWER REQUIREMENTS
The Load Bank requires a 115V, single phase, 60 Hz, 15 amp source of power for operation of
the control circuit which is provided by an integral 240/480 to 115V control transformer.
This enables the operator to use the generator output for control power. When the operator
applies either 240V or 480V to the primary, the control transformer supplies 120 VAC for
control power. An external power source must be provided (as described in section B of Fan
Motor Connections) if internal power for motor and control power is not desired.
During startup, be sure the load switch on the generator under test is not "ON" until the prime
mover has the generator up to speed. Also, be sure the load switch is OFF before generator
shutdown procedures are started.
*******************************************************
C A U T I O N
The Load Bank includes a control transformer. Never connect a
control power line cord to TB1(1) and TB1 (2). This would
permanently damage the control transformer.
*******************************************************
FAN MOTOR CONNECTIONS
The fan circuit consists of fuses, motor starters, contactors, overload relays, and the fan motor.
A. INTERNAL BLOWER POWER OPERATION: The fan is connected to load bus
through relay K28 and fuses F7, 8, and 9. When operating the fan motor from the
generator source, an additional load of 2400 watts will be applied. This additional load
will be reflected in the meter readings and should be noted on load readings to prevent
errors.

Installation Avtron Model LPH 400 • Resistive Load Bank
Part Number LPH400D43233
3-4
B. REMOTE FAN POWER OPERATION: When testing single phase system or systems or
a frequency other than 60 Hz, the fan motor must be run from a separate source. First
review schematic, set control panel selector switch to match external voltage applied, and
then connect external power. To do this, locate TB2 internally on the side of the
customer load connection compartment at the intake end of the Load Bank. Connect the
external fan power source to terminals 1 through 3 of TB2.
C. NON-STANDARD FAN MOTOR FREQUENCY: Fan motor will operate between 208
and 250 volts and between 416 and 500 volts at 3-phase, 60 Hz.
Connection at 50 Hz is the same as 60 Hz, with motor voltage range of 180 to 220 volts and 360
to 440 volts.
******************************************************
W A R N I N G
When operating at 50 Hz, the motor speed (RPM) is reduced,
which also reduces cooling of the Load Bank. Do not exceed
400 volts in the 480 mode or 200 volts in the 240 mode, to input
bus when running the fan at 50 Hz.
******************************************************
C A U T I O N
Do not attempt to operate fan motor at 400 Hz. When loading unit
with power other than 50/60 Hz, the fan motor must be wired to
external power source supplying any of the above proper voltages
and frequencies.
******************************************************
NOTE
Follow correct jumper configuration on TB2 as shown on the
schematic before applying load or external fan power.

Installation Avtron Model LPH 400 • Resistive Load Bank
Part Number LPH400D43233
3-5
LOAD CONNECTION
Connect a 240/480 volt, 3-phase source to the three fused bars labeled A, B and C, located in the
customer connection access box. Cables to the Load Bank should be sized to handle the
maximum rated load according to the National Electric Code. Verify load cables, lugs, and
mounting hardware have sufficient arc over clearance to sheet metal and cover when closed.
The current can be determined by the following formula:
Line Current = kW x 577
VOLTAGE (Line to Line)
*******************************************************
W A R N I N G
"B" Bus and any attached wiring are electrically hot when
operating Load Bank in single phase.
*******************************************************
GROUNDING
A permanent ground should be connected to the Load Bank enclosure either by a grounded
conduit or with a separate ground wire to prevent a potential above ground on the enclosure. No
internal ground connections are made to any terminal on the Load Bank.

Installation Avtron Model LPH 400 • Resistive Load Bank
Part Number LPH400D43233
3-6
The ground conductor should be run with the load power conductors to provide the lowest
impedance fault path. The ground stud must be connected to both the generator frame and a
good earth ground. The ground conductor should be sized for National Electric Code section
250.122 if not superseded by local codes.
******************************************************
W A R N I N G
Do not operate the Load Bank with any panel or screen removed.
This may expose the operator to dangerous high voltage and the
rotating fan blade, as well as disrupting the airflow.
Keep the hinged cover on connection access box closed and
latched.
******************************************************
STORAGE
The Load Bank should be covered to limit long term effect of moisture and to reduce the
accumulation of dust and dirt. The unit should be stored in a dry, enclosed area. An optional
waterproof vinyl cover is available for the Load Bank; however, even with this cover, the Load
Bank should not be stored outdoors permanently.

Operation Avtron Model LPH 400 • Resistive Load Bank
Part Number LPH400D43233
4-1
SECTION IV
OPERATION
PURPOSE AND USE OF CONTROLS
1. BLOWER VOLTAGE SELECT Switch. This switch selects the appropriate voltage and
source for the fan motor. Set to proper position BEFORE operation.
2. LOAD VOLTAGE SELECT 240/208/416/480 Switch. This switch selects the 240 or
480 load voltage mode for the Load Bank.
3. CONTROL POWER INTEGRAL XFMR 240V/480V Select Switch. This switch is used
to set correct input voltage to the Control Transformer. This method should be used only
if voltage and frequency of the generator under test falls within the ranges specified in
the INSTALLATION section.
4. BLOWER START/STOP Pushbuttons. Pushbuttons are used to initiate fan motor start
and stop circuits.
5. FAN ROTATION ABC/CBA Switch. This switch is used to reverse the rotation of the
cooling fan if airflow is moving in the wrong direction. Always turn off fan by pressing
the BLOWER STOP switch and allow the fan to coast to a stop before changing the FAN
ROTATION ABC/CBA switch setting.
6. BLOWER FAIL Lamp. This lamp should momentarily light when power switch is
turned on. This shows the air safety circuit is working. This lamp's purpose is to warn
the operator of an air failure or improper cooling of load elements.
7. Digital Metering Package - Operation is performed through the front panel of the meter.
See supplemental manual for complete operation instructions.
8. MASTER LOAD ON/OFF Switch. This switch connects power to all load steps, thus
allowing all set load steps to be actuated at the same time. It is also a master load
disconnect.
9. kW LOAD Step Switches. The load in kilowatts is marked above each actuating switch.

Operation Avtron Model LPH 400 • Resistive Load Bank
Part Number LPH400D43233
4-2
A load step may be turned on or off before or during a test, but will load the unit only
when the MASTER LOAD switch is ON.
OPERATING INSTRUCTIONS
1. Connect the unit to be tested as described in Section III, INSTALLATION, under Power
Requirements. Use all three load bus bars in the customer connection access box for
3-phase generators, or connect the power cables to the Phase A and Phase C bus bars for
single phase generators. (See Section III, INSTALLATION, for details.)
*******************************************************
C A U T I O N
The cooling fan motor is rated at 208-240/480 volts, 3-phase,
60 Hz, with corresponding overload heaters for protection. The
motor must be connected to a separate power source if:
1. Using the unit to test a single phase unit.
2. Operating at any frequencies other than 50/60 Hz.
3. Operating at any voltage other than 240/480 volts ±10 @
60 Hz.
(Refer to Non-Standard Blower Motor Frequency in Section III.)
*******************************************************
2. Place all switches on the control panel in the OFF position.
3. Place the BLOWER VOLTAGE SELECT switch to the correct voltage and source
selection.
4. Place the LOAD VOLTAGE SELECT switch to the correct voltage to test the generator.
5. Start the generator to be tested. After unit stabilizes at operating speed, temperature,
voltage, and any other required condition for testing per manufacturer’s instructions,
proceed to step 7.
*******************************************************

Operation Avtron Model LPH 400 • Resistive Load Bank
Part Number LPH400D43233
4-3
C A U T I O N
DO NOT operate the Load Bank over the rated voltage as this will
cause catastrophic failure in the Load Bank.
DO make sure that the VOLTS Select switch is in the proper
position before applying load.
*******************************************************
6. Move the CONTROL POWER INTEGRAL XFMR 240V/480V selector switch to the
voltage that matches the generator under test. Press the control power ON button.
7. Depress the BLOWER START pushbutton. Verify air flow is in the correct direction. If
not, shut down fan by depressing the STOP pushbutton. Wait until fan blade stops
rotating, then switch fan rotation switch ABC/CBA. Restart and verify airflow.
Upon energizing the fan, the red BLOWER FAIL lamp will light momentarily until the
air switch detects sufficient cooling air, at which time it will go out, applying power load
switches. If at any time, there is insufficient cooling air to the elements, this safety
switch will drop out the load and the red BLOWER FAIL lamp will light.
*******************************************************
C A U T I O N
The operation of the fan is vital to the safe operation of this Load
Bank. When the BLOWER START pushbutton is depressed, the
BLOWER FAIL light will come on momentarily until the blower
accelerates up to its operating speed, at which time the light will
go off. If the air switch prevents the load from being applied, do
not bypass this switch. If the BLOWER FAIL light stays on for
more than a few seconds, shut down the Load Bank and do not
operate the unit until the problem is corrected. (Refer to Section I,
SAFETY CONSIDERATIONS, of this manual.)
*******************************************************
8. With the MASTER LOAD switch in the OFF position, verify that the voltage displayed
by the Digital Meter matches the position of the LOAD VOLTAGE Select switch.
9. The resistive loading is selected by toggle switches, using any one or combination of
toggle switches to make up a given load.
10. By placing the MASTER LOAD switch to the ON position, the preselected load will be
applied to the power source.

Operation Avtron Model LPH 400 • Resistive Load Bank
Part Number LPH400D43233
4-4
11. Any kW LOAD switch can be added or removed as required with the MASTER LOAD
switch closed (ON).
12. Monitor the unit under test using the digital metering package. Toggle through the
phases to review individual phase amps, kW, and volts.
13. To remove load, move MASTER LOAD switch to OFF position.
14. Shutdown: Reverse steps 1 through 12. It is good procedure to allow the fan motor to
operate for about 5 minutes after the load is removed. This will exhaust any accumulated
heat and allow exhaust surfaces to cool. Although not required for maintaining Load
Bank integrity, the cooling procedure helps to prevent burn injuries.
*******************************************************
W A R N I N G
DO NOT touch the exhaust screen during operation. The screen
will become hot from the exhaust heat and may cause a serious
burn. (Refer to Section I, SAFETY CONSIDERATIONS, of this
manual.)
DO NOT allow objects to enter or block screens.
*******************************************************
NOTE
Lower voltages and different frequencies may be applied to the
load circuit of the Load Bank. Frequency change causes no
derating of the load. The Applied kW with a lower voltage is
computed using the following formula:
)
RatedVoltage(
)
AppliedVoltage(
kW
=
kW 2
2
RatedApplied 
*******************************************************
C A U T I O N

Operation Avtron Model LPH 400 • Resistive Load Bank
Part Number LPH400D43233
4-5
Never exceed the rated voltage. This will cause the Load Bank to
overheat.
Do not apply DC voltages, because the contactors do not have arc
blowout magnets.
*******************************************************

Maintenance Avtron Model LPH 400 • Resistive Load Bank
Part Number LPH400D43233
5-1
SECTION V
MAINTENANCE
Good maintenance procedures must be followed to provide long equipment life and to reduce the
chance of electric shock, fires, and personal injury. Before servicing, review Section I, SAFETY
CONSIDERATIONS, of this manual.
The following are examples of scheduled maintenance procedures. These examples are not
purported to be all-inclusive, but must be accomplished to maintain the equipment in a good,
safe condition. All maintenance work must be done by qualified personnel only.
*******************************************************
W A R N I N G
Personal injury from electrical shock or from the rotating fan blade
may result if ALL sources of power are not disconnected before
servicing. (Refer to Section I, SAFETY CONSIDERATIONS, of
this manual.)
*******************************************************
DAILY
1. Remove any Load Bank airflow restrictions.
2. Check the screens to make sure that no objects have blocked or entered the openings.
Also verify screens are not damaged. Repair or replace any damaged screens.
3. Verify that the airflow is in the proper direction.
4. Ensure that there is no recirculation of the exhaust air through the Load Bank.

Maintenance Avtron Model LPH 400 • Resistive Load Bank
Part Number LPH400D43233
5-2
THREE MONTHS OR 500 HOURS
1. Remove access panels and screens.
2. Inspect the load resistors for mechanical breakdown which is demonstrated by excessive
sagging of the elements. Replace with new resistor elements, support rods, and insulators
as required.
3. Inspect for broken ceramic insulators. Replace with new ceramic insulators if any cracks
are found. Minor chips (less than 1/8" diameter) are acceptable and not cause for
replacement.
4. Inspect for loose hardware or loose connections. Tighten where required.
5. Inspect all connections for oxidation or corrosion. Clean the connection or replace the
hardware where required.
6. Verify that the airflow switch works properly.
7. Inspect all contactors to make sure that the contacts are not severely pitted or corroded.
The contacts must move freely and be properly seated.
8. Clean all dirt and debris out of the Load Bank. This can be accomplished by blowing the
inside of the unit with clean, dry compressed air.
*******************************************************
W A R N I N G
Use only clean, dry compressed air (not to exceed 40 PSI). Eye
protection must be worn when cleaning with compressed air. Do
not direct compressed air against skin.
*******************************************************
9. Inspect all the wiring for any sign of insulation failure, especially where wiring is close to
resistor case sheet metal or element support rod or clip.
10. Care must be taken in repairing or replacing current transformers. If one is found to be
defective, mark all leads before removing to ensure connecting new C.T. properly, since
proper phasing is important.
11. Inspect for any signs of heat stress on connections. This could be caused by loose
hardware or corroded connection. Repair or replace as condition warrants.