Asco 4820 User manual

P/N: D29650-14, 3-17
4820 Load Bank
User Manual

ASCO MODEL K875A
OUTDOOR LOAD BANK
© 2016 ASCO Power Technologies, Inc. January 6, 2000
Cleveland, Ohio Rev. July 7, 2016

6255 Halle Drive, Cleveland, OH 44125-4615 -216.573.7600 -f: 216.573.5953
www.avtronloadbank.com Form 831B-LB Rev. 11-16
PROPRIETARY NOTE
This document contains information PROPRIETARY TO Avtron
Load Bank branded products and systems by ASCO Power
Technologies, LP. It is furnished solely to provide information
sufficient for instruction, operation, maintenance, evaluation,
and testing of the equipment herein disclosed; is not to be used
for manufacturing or procurement; and is not to be disclosed to
anyone other than persons in the Division, or the Company, or
the Government, as the case may be, responsible for action
relating to this document without the express written permission
of ASCO Power Technologies, LP.
WARRANTY
The last page of this document contains an express limited
warranty. The provisions of this warranty cover any and all rights
extended to holders of Avtron Load Bank branded products and
systems by ASCO Power Technologies, LP.

ASCO POWER TECHNOLOGIES, INC.
Cleveland, Ohio
ASCO MODEL K875A
OUTDOOR LOAD BANK
TABLE OF CONTENTS
Page
Section I SAFETY CONSIDERATIONS.................................................................1-1
Section II DESCRIPTION..........................................................................................2-1
Section III INSTALLATION ......................................................................................3-1
Section IV OPERATION.............................................................................................4-1
Section V MAINTENANCE......................................................................................5-1
Section VI OPTIONS...................................................................................................6-1
Section VII REPLACEMENT PARTS LIST................................................................7-1
APPENDIX - Load Bank Troubleshooting Guide
DRAWINGS
See tables on the following two pages. See column 1 for the part number purchased. Drawings
are provided at the end of this manual based on the specific Load Bank purchased.
OPTION DRAWING(S) AND INSTRUCTIONS
Option drawings are provided for options purchased. A list of option drawings begins after
page iii.
Instruction Manual Part Number D29421-X Manual is provided if this option is purchased.
Instruction Manual Part Number D29785-X Manual is provided if this option is purchased.
-i-

Table of Contents ASCO Model K875A Outdoor Load Bank
DRAWINGS
Part No. kW Volts Load Steps O/L Dwg. Schem. Interconn.
K875AD28042-4 2500 480 50, 50, 100, 100, 200, 500, 500,
500, 500 SB2770 1D30049 D30349
K875AD28042-5 3000 480 50, 50, 100, 100, 200, 500, 500,
500, 500, 500 SB2770 1D30051 D30350
K875AD28042-6 3000 480 50, 50, 100, 100, 200, 500, 500,
500, 500, 500 SB2770 1D31135 D31136
K875AD28042-7 2500 480 5, 10, 10, 25, 50, 100, 100, 200,
500, 500, 500, 500 SB2770 1D38361 D38362
K875AD28042-8 3000 480 5, 10, 10, 25, 50, 100, 100, 200,
500, 500, 500, 500, 500 SB2770 1D42596 D42595
K875AD29440-2 750 480 50, 100, 200, 200, 200 SB2793 2D29809 D29810
K875AD29440-3 750 480 5, 10, 10, 25, 50, 50, 100, 100,
200, 200 SB2793 2D29811 D29812
K875AD29440-4 1000 480 50, 50, 100, 100, 200, 500 SB2793 2D29813 D29814
K875AD29440-5 1000 480 5, 10, 10, 25, 50, 100, 100,
200, 500 SB2793 2D29815 D29816
K875AD29440-6 1000 480 5, 10, 10, 25, 50, 100, 100, 200,
500 SB2793 2D30417 D30416
K875AD29440-10 750 480 25, 25, 50, 50, 100, 100, 200,
200 SB2793 2D42645 D42646
K875AD29461-1 750 240/480 5, 10, 10, 25, 50, 50, 100, 100,
200, 200 SB2793 2D29826 D29827
K875AD29461-2 1000 240/480 50, 50, 100, 100, 200, 500 SB2793 2D29828 D29829
K875AD29461-3 750 240/480 50, 100, 200, 200, 200 SB2793 2D29822 D29823
K875AD29461-4 1000 240/480 5, 10, 10, 25, 50, 100, 100, 200,
500 SB2793 2D29824 D29825
K875AD29461-5 1000
700
480
240
5, 10, 10, 25, 50, 100, 200, 200,
400
5, 10, 10, 25, 50, 100, 100, 200,
200
SB2793 2D31287 D31288
K875AD29650-3 1500 480 5, 10, 10, 25, 50, 100, 100, 200,
500, 500 SB2827 3D30041 D30278
K875AD29650-4 1500 480 50, 50, 100, 100, 200, 500, 500 SB2827 3D30042 D30125
K875AD29650-5 1500 240/480 5, 10, 10, 25, 50, 100, 100, 200,
500, 500 SB2827 3D30043 D30126
K875AD29650-6 1500 240/480 50, 50, 100, 100, 200, 500, 500 SB2827 3D30044 D30127
K875AD29650-7 2000 480 5, 10, 10, 25, 50, 100, 100, 200,
500, 500, 500 SB2827 3D30088 D30089
K875AD29650-8 2000 480 50, 50, 100, 100, 200, 500, 500,
500 SB2827 3D30047 D30296
K875AD29650-9 2000 480 50, 50, 100, 100, 200, 500, 500,
500 SB2827 3D30047 D30296
K875AD29650-14 1250 480 50, 100, 100, 100, 200, 200,
500 SB2827 3D35454 D35453
K875AD36922-1 1250 480 5, 10, 10, 25, 50, 50, 100, 100,
200, 200, 500 SB2827 3D36923 D36924
See the following page for additional drawings. -ii-

Table of Contents ASCO Model K875A Outdoor Load Bank
DRAWINGS
Part No. No. of
Stacks Control Panel O/L Dwg., Control Panel Resistor Assemblies
K875AD28042-4 Three D29743-17 SB2950 D27553-1, D27555-1
K875AD28042-5 Three D29743-18 SB2950 D27555-1, D28438-2
K875AD28042-6 Three D31297 -- D28438-2, D27555-1
K875AD28042-7 Three D29743-30 SB2950 D28438-2, D27555-1, D27554-1,
D27552-1
K875AD28042-8 Three D29743-33 SB2950 D27552-1, D27553-1, D27555-1
K875AD29440-2 One D29743-5 SB2950 D27553-1, D27555-1
K875AD29440-3 One D29743-6 SB2950 D27552-1, D27553-1, D27555-1
K875AD29440-4 One D29743-7 SB2950 D27555-1, D28438-2
K875AD29440-5 One D29743-8 SB2950 D27552-1, D27553-1, D27555-1
K875AD29440-6 One D30415 SB2988 D27552-1, D27555-1
K875AD29440-10 One D29743-34 SB2950 D27553-1, D27555-1, D34941
K875AD29461-1 One D29743-9 SB2950 D27552-2, D27553-2, D27555-2,
D29645
K875AD29461-2 One D29743-10 SB2950 D27553-2, D27555-2, D29589-1
K875AD29461-3 One D29743-3 SB2950 D27553-2, D27555-2, D29645, D29851
K875AD29461-4 One D29743-4 SB2950 D27552-2, D27553-2, D27555-2
K875AD29461-5 One D29743-22 SB2950 D27552-2, D27553-2, D27555-2,
D27555-4
K875AD29650-3 Two D29743-12 SB2950 D27552-1, D27553-1, D27554-1,
D27555-1
K875AD29650-4 Two D29743-11 SB2950 D27553-1, D27555-1
K875AD29650-5 Two D29743-13 SB2950 D27552-2, D27553-2, D27554-2,
D27555-2, D29645, D29851
K875AD29650-6 Two D29743-14 SB2950 D27553-2, D27555-1, D29645, D29851
K875AD29650-7 Two D29743-15 SB2950 D27552-1, D27553-1, D27555-1
K875AD29650-8 Two D29743-19 SB2950 D27555-1, D28438-2
K875AD29650-9 Two D29743-19 SB2950 D27555-1, D28438-2
K875AD29650-14 Two D29743-26 SB2950 D27553-1, D27554-1, D27555-1
K875AD36922-1 Two D36925-1 SB2950 D27555-1, D28438-2, D27552-1
1For Load Banks equipped with Option 75, use Outline Drawing SB3147.
2For Load Banks equipped with Option 73, use Outline Drawing SB3145.
3For Load Banks equipped with Option 74, use Outline Drawing SB3146.
-iii-

Options ASCO Model 4800 Load Bank
TABLE OF CONTENTS (Cont.)
OPTIONS - Refer to Section VI (K875A OPTIONS LIST) of this manual. The following
drawings apply to the various options. Only drawings for the options provided have
been included in this manual. Not all options can be installed in the same unit.
Drawing Option Description
SB2196 17 Control/Meter Enclosure, Wallmount (Outline)
1192769 23 Automatic Load Controller Option (Schematic)
1192769 24 Automatic Load Controller Option (Schematic)
B27730 36 Remote Monitoring Contacts
D27683-9 51 Control Transformer Option, 208/115V
D37723-3 64 Digital Power Metering Option (DW Style)
(V, A, F, KW, KVAR, PF, KVA) CT Ratio: 1500:5
D37723-4 65 Digital Power Metering Option (DW Style)
(V, A, F, KW, KVAR, PF, KVA) CT Ratio: 2000:5
A32404 71 Control Unit, Mounted (Front)
*A32573-1 73 Gravity Hood Replacement, Single Stack
A32573-2 74 Gravity Hood Replacement, Two Stack
A33333-1 76 Hinged Access Panel, Single Stack
A34920-1 80 Aluminum Hood Replacement with Stainless Steel
Screen (1 Stack Units)
B32580-1 83 Overhead Lift, Single Stack
B32580-2 84 Overhead Lift, Two Stack
A37255 86 Bus Bar, Customer Connection, Replacement
A37594 87 Local Control/Metering Unit, Mounted (Right Side)
B33795-1 88 Elevating Stand (One Bay)
*Load Banks equipped with Option 73 should be supplied with special Outline Drawing SB3145.

1-1
ASCO MODEL K875A
OUTDOOR LOAD BANK
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 ASCO 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 proven
reliable 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 ASCO equipment.
The Model K875A Load Bank is an industrial test unit designed to be used outdoors safely with an
exhaust hood. (The unit should not be installed indoors.) However, because the function of the
Load Bank is to dissipate electrical energy, there are inherent dangers to operators and equipment.
These dangers are 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 fans/blowers. If there is any restriction or stoppage of airflow, the Load Bank
will overheat and may start a fire. It is recommended that:
1. The operator should read the manual before using the Load Bank.
2. Run an approved ground wire from the Load Bank ground lug(s) to the generator frame.
Run an approved ground wire from the generator frame to a goodearth ground. Size ground
wire in accordance with National Electrical Code and any local codes.
3. Do not bypass the airflow safety switch or exhaust over-temperature switch to prevent
nuisance tripping.

Safety Considerations ASCO Model K875A Outdoor Load Bank
1-2
4. 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.
5. Maintenance personnel must always exercise caution when the access panels or intake
screens are removed. Personal injury from electrical shock or from the rotating fan blades
may result if all sources of power are not disconnected before servicing. Maintenance work
must be done only by qualified personnel.
6. The Load Bank must be used 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. This causes a constant rise in cooling air temperature and may cause the Load
Bank to overheat.
7. Install the factory-provided exhaust hood(s) as soon as possible. This protects the open
resistor element section from debris and environmental conditions such as freezing rain.
Failure to install hoods in a timely fashion may void warranty.
8. Venting the heated air from the exhaust toward overhead cables, sprinkler systems, or into a
room with insufficient volume or "Make-Up" air is a definite hazard. The Load Banks
should be used in a cool, well ventilated area. This Load Bank is specifically designed for
outdoor use with an exhaust hood. Load Banks are not intended for indoor operation.
9. After running a load test, residual heat may be removed fromthe Load Bank by allowing the
fans 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.
10. 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.
11. Do not allow objects to enter or block the air intake or exhaust of the Load Bank. A blockage
can 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/or fire hazards.
12. Operators must not operate the Load Bank with the access panels or screens removed. To do
so exposes the operator and other persons to possible personal injury from electrical shock or
from the moving fan blades.
13. Emergency Shutdown Procedure
A. In an emergency, turn off the MASTER LOAD switch, then the generator. The
MASTER LOAD switch will allow disconnection of all load steps and still allow for
the motor to run, cooling any heated elements.

Safety Considerations ASCO Model K875A Outdoor Load Bank
1-3
B. The power ON/OFF switch will disconnect both load steps and the fan motor. The
Generator Emergency "OFF" switch should be located near the load system.
14. An approved electrical fire extinguisher should be on hand at all times.
15. 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.
16. Read and heed all WARNING and CAUTION statements in the manual.

Description ASCO Model K875A Outdoor Load Bank
2-1
SECTION II
DESCRIPTION
The ASCO Model K875A Resistive Load Bank is a vertical airflow unit designed to provide a
balanced resistive load of unity power factor, at a specified 3-phase voltage. The total load
capability and load steps provided in a given K875A Load Bank are listed in the Table of Contents.
The standard Load Bank step resolution is either 5 kW or 50 kW; 1 kWresolution is available as an
option. K875AD29440-10 has a Load Step Resolution of 25 kW. Using the toggle switches on the
control panel, any combination of the available load steps may be selected to achieve a desired load.
Depending on the total kW capability, the K875A Load Bank consists of one, two, or three stacks.
Each stack contains a blower with a 3-phase, 480 VAC, 60 Hz, 10 H.P. 1750 RPM fan motor which
provides the necessary cooling air for the load elements. The fan motor is controlled by a motor
starter contactor. Overcurrent protection is provided for the motor by three fuses and an overload
relay. The overload relay assembly does not have an automatic reset provision and must be reset
manually. When required, the Load Bank may be furnished with blower motor(s) sized to operate at
voltages different from standard. The fan free air delivery is nominally 20,000 CFM.
*******************************************************
C A U T I O N
The Load Bank should never be used without the fan motor(s)
operating. Inadequate cooling airflow will result in resistor elements
causing overheating and a definite fire hazard.
*******************************************************
An airflow switch (one per stack) is provided to monitor the flow of cooling air. This differential
pressure switch is electrically interlocked with the load application controls to prevent load
application if a fan is not working properly (AIR FAILURE light comes on).
An overtemperature switch (one per stack) is provided to monitor exhaust air temperature. This
switch is electrically interlocked with the load application controls to prevent load application if a
resistor stack temperature exceeds 375F.

Description ASCO Model K875A Outdoor Load Bank
2-2
The control panel contains a POWER ON-OFF switch with a CONTROL POWER light, a
BLOWER POWER light, blower power START and STOP pushbutton switches, an AIR FAILURE
light, a Load Bank OVER TEMP light, a MASTER LOAD ON-OFF switch, a VOLTAGE SELECT
switch for Load Banks with dual voltage capability, and individual KW LOAD STEP switches. All
load step switches are the toggle type with metal levers. The control panel also contains a FUSE for
protection of the control circuit.
Also, for Load Banks equipped with the Load Shed option, the control panel will contain an
AUTO/MANUAL selector switch and an AUTO light. Various digital metering packages are
optionally available and are packaged as part of the control panel.
Sized for mounting in a 19-inch rack enclosure, the control panel has a vertical height of 14 inches
and requires a minimum of 8 inches of clearance behind the panel.
A control panel enclosure, for control panels with or without metering, is available as an option. It
can be supplied mounted directly to the Load Bank or loose for mounting in a remote location.
The K875A Load Bank is fabricated using heavy-gauge aluminized sheet steel, making a rigid
structure. Mounted within the structure are the load element resistor assemblies, load contactors,
and the cooling fan(s)/blower(s). The resistive elements are porcupine type, fully supported along
their length. Mounted on separate panels are the motor starter, motor overload relay, fuses, and
customer connection terminals. The cooling air is drawn in from the sides and the back intake
screens, forced across the resistor elements, and exhausted out the top. The panel includes a
temperature controlled heater, which may be used to prevent condensation from hindering operation
of the Load Bank.
The Load Bank is equipped with screens mounted at the inlet openings and exhaust hoods. The Load
Bank uses a welded fabricated base to facilitate handling by a forklift truck. Bolt holes are also
supplied in the base to permit permanent mounting to a concrete pad or metal foundation.
*******************************************************
W A R N I N G
Never exceed the rated voltage as this will cause the Load Bank to
overheat.
Do not apply DC voltages as the contactors do not have arc blowout
magnets.
*******************************************************

Installation ASCO Model K875A Outdoor Load Bank
3-1
SECTION III
INSTALLATION
INSTALLATION CHECKOUT PROCEDURE -
TO BE DONE PRIOR TO OPERATION
This Installation Checkout Procedure is intended to be used upon initial receipt of equipment and
following any relocation of a permanent mounted Load Bank. These procedures apply to Load
Banks in general and may include steps not relevant to the specific unit being installed. Disregard
those procedures which do not apply.
*******************************************************
W A R N I N G
THE FOLLOWING TESTS ARE TO BE ACCOMPLISHED BY A
QUALIFIED ELECTRICIAN OR TECHNICIAN USING
EXTREME CAUTION AS POTENTIALLY LETHAL VOLTAGES
ANDDANGEROUSROTATINGCOMPONENTS ARE PRESENT.
IF ASSISTANCE IS REQUIRED, ASCO CAN PROVIDE START
UP SERVICE AT A NOMINAL CHARGE. ASCO ALSO WILL
PROVIDE TELEPHONE ASSISTANCE IF REQUIRED BY
CALLING [phone].
*******************************************************
1. Verify the Load Bank placement meets the installation requirements found in the
INSTALLATION section of the instruction manual:
A. Check the clearance from both intake and exhaust to any obstruction.
B. If the location has a prevailing wind, make the wind aid in the cooling of the resistor
elements.

Installation ASCO Model K875A Outdoor Load Bank
3-2
C. Follow these steps to mount hoods on exhaust (top) of Load Bank.
1) Hoist hoods by installing two heavy rods (5/8" or 3/4" dia.) completely
through unit.
2) Make sure at least 6" projects beyond sides.
3) Then attach minimum 6' long four-chain/cable sling to rod ends.
4) Anchor hoisting device.
5) Verify device with attachments will safely hoist hoods.
6) Lift hoods and seat over full perimeter flange (curb) on roof (top) of Load
Bank.
7) Mounting can be directed toward front or rear of Load Bank.
8) Secure. Use 3/8-16 S/S fasteners provided. (Fasteners are shipped screwed
into hood mounting flange on top of unit.)
2. Check the mechanical integrity of all customer-supplied interconnection wiring:
A. Ensure lugs are properly crimped.
B. Ensure terminations are properly torqued.
C. Verify proper phase to phase clearance on main bus bars, load wiring, and
mounting hardware.
3. Utilize system schematics to ohm out customer-supplied interconnection control wiring and
safety circuits:
A. If control wiring is all the same color, ohm out each individual wire to confirm
proper labeling and placement.
C A U T I O N
Control wiring must be a minimum of 14 AWG for wire runs
under 50 feet. Consult ASCO factory for wire sizing when
wire run exceeds 50 feet.
B. Confirm the correct wire gauge has been used for interconnection wiring. Control
wiring should be a minimum of 14 AWG for control panel to Load Bank lengths of
50 feet or less. For lengths of greater than 50 feet, consult the factory.

Installation ASCO Model K875A Outdoor Load Bank
3-3
4. Energize the source of control power only:
A. Check the control voltage and confirm it is within 10% of the required voltage.
******************************************************
W A R N I N G
Control power is present on terminal block in steps 4 through 6.
*******************************************************
B. Operate the safety circuitry with a jumper across the air switch contact at its
termination at the terminal block.
5. Verify the proper relays energize with each individual load switch.
A. Turn on each load step individually and observe that each relay or relays pulls in
without chatter or hesitation.
B. Turn off the master load switch. Turn on all the load steps. Turn the master load on
and observe the pull in of all the contactors. If chatter or hesitation is observed,
locate the cause of the voltage drop causing the problem.
6. While the load relays are energized, remove the jumper across the air switch. All the load
contactors should drop. Leave the jumper off the air switch(es).
7. Apply the rated fan voltage. Start fans/blowers and verify that air is exiting the resistor
assembly end (top of exhaust hood).
The air switches must be checked and/or field adjusted. This adjustment must be made after
installation and during full operation of any supplemental equipment, which may influence
the air-handling system. Follow these steps to verify and/or adjust:
A. Stop fan(s)/blower(s) and remove all sources of power from the Load Bank.
B. Remove the front access panel to gain entry to the control area.
C. Verify each air switch individually by removing the control wiring from the switch
terminals.
D. Connect an ohmmeter across the air switch normally open terminals.

Installation ASCO Model K875A Outdoor Load Bank
3-4
E. Run ohmmeter wiring outside of the unit and temporarily install access panel.
F. Reapply fan/blower voltage and control power.
G. Start fan(s), allowing them to come up to speed, approximately 10 seconds. The
normally open contacts should close. If more than one fan/blower, all must be
operating before continuing.
H. Press fan/blower stop button. Count down the number of seconds before switch
opens. It should take 3-5 seconds. If not, adjust the air switch by turning the screw
on the air switch out to increase time. (Turning in decreases time.)
I. Once 3-5 seconds have been established, repeat for the other air switch(es) if
applicable.
J. Stop fan(s) and remove all sources of power from the Load Bank.
K. Remove access panel, remove ohmmeter wiring,andreplace factory wiring. Replace
access panel.
This checkout procedure is intended to be a guide to Load Bank installations in general. Special
installation considerations not addressed herein may be necessary due to installation site or
environment. Any questions or concerns regarding Load Bank installation should be directed to
field service at [phone].
*******************************************************
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 causes a safety hazard and voids our
warranty. Verify proper phase to phase clearances on all load wiring,
bus bar, and mounting hardware. The following installation
instructions are critical to the safe operation of the Load Bank. Refer
to the SAFETY CONSIDERATIONS section of this manual.
*******************************************************

Installation ASCO Model K875A Outdoor Load Bank
3-5
LOCATION
Do not install the Load Bank in any area where standing water can pool or accumulate. Do not
install near: a drainage basin, surface/ground or roof runoff, sewer collection, or any location where
water can back up or collect. If flooding can occur, we recommend a different location or a raised
platform sufficiently above high water level. Do not operate if any portion of the Load Bank is
submerged. Always install above grade.
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. The
Load Bank must not be operated in a closed space. Exhaust temperature may exceed 400F over
ambient, under full load conditions.
The Load Bank should be positioned so that there is a minimum of 36 inches of clearance on all
sides to provide room for intake air flow and maintenance. A minimumof twelve feet of clearance
from the exhaust is required for proper airflow. (Refer to the appropriate Outline Drawing.)
The exhaust air may exceed 400F 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.
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
elements. A Load Bank should not be installed so close to any surface as to reflect the
exhausted air back to the air intake.
2. Restriction of Cooling Air - Any obstruction located within five (5) feet of the inlet and
twelve (12) feet of the exhaust hood 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. It is
recommended that the factory exhaust hoods be used.
NOTE
If exhaust hoods are not used, contact the factory for specific site
review prior to installation and operation. The following three items
are for review.

Installation ASCO Model K875A Outdoor Load Bank
3-6
a. If the exhaust hoods are not used, the Load Banks are designed to tolerate up to 0.12"
water gage additional system airflow resistance. This includes air intake resistance
and resistance due to exhaust duct/louvers/screen. The exhaust must be screened to
keep debris from entering unit. The screen must be a minimum 75% open area
and/or exceed Load Bank duct area by a minimum of 50%.
b. If exhaust duct exits through motorized louvers, the design must be interlocked to
assure full open prior to operation. Consideration must also be given for louver
design and actuator to prevent heat problems.
c. Each fan/blower is designed to move 20,000 CFM per resistor stack. The entire unit
then moves (20,000 CFM times number of stacks).
Consult the factory if hoods are not used or if strong prevailing winds exist. Failure to obtain
written factory approval for special intake or exhaust conditions voids warranty.
ADDITIONAL AIRFLOW CONSIDERATIONS
1. Load Banks mounted into a channel, trough, hollow, well, pit, surrounded completely by a
parapet wall or backed into a full corner require special considerations even if the other
conditions are met. In these cases, provide detailed site layout drawings to ASCO for
inspection and comments.
2. Locations which have full or partial perimeter fence necessitate a review. The fencing
material should have at least 75% open area. The minimum clearances still apply. Overhead
fencing or grating is not recommended.
3. Do not install Load Banks or other air handling devices within the same area. Any high
velocity air stream near the Load Bank air flow can disrupt the cooling. This is critical if the
other equipment is a source of heat. Any thermal rise on Load Bank intake air can create a
potential hazard.
4. The Load Bank cooling system cannot be used for any purpose other than cooling the Load
Bank.
5. In northern climates with snow depths exceeding 6 inches or blowing and drifting snow, a
physical inspection of the Load Bank intake and exhaust is required prior to operation. Any
significant snow drifts or snow depths must be cleared prior to operation.
6. Standard Load Banks are designed for operation between sea level and 2,000 feet maximum
altitudes. Operation at altitudes over 2,000 feet above sea level requires special
consideration. As the altitude increases, the effective cooling air diminishes. Contact ASCO
for assistance.

Installation ASCO Model K875A Outdoor Load Bank
3-7
SPECIAL NOTE FOR THREE STACK LOAD BANKS (P/N D28042-)
These higher capacity three stack (bays/modules) units require special airflow consideration. The
center stack must pull in cool intake air from the back and bottom of the stack. Do NOT block or
restrict the back or lower (base) screened intake areas. Although the center stack is typically used
for primary load connection, the contractor installed and fabricated wire way/duct run/conduit must
be clear of these center stack intakes.
CONTROL CONNECTIONS
The control panel is designed for mounting in a 19-inch rack-type enclosure. If required, connect
terminals of the control panel to terminals of the Load Bank and conduit/wire way as shown on the
appropriate interconnection diagram. The control circuit operates on a customer-supplied 120 VAC,
60 Hz, single phase, 20 amp power source. On three stack designs, verify conduit/wire way does not
impede airflow to center stack.
As an option, the control circuit voltage is obtained from the main load bus using the appropriate
control transformer assembly.
ENCLOSURE HEATERS
A 100 watt strip heater is located inside the Load Bank enclosure (one per stack) on the
control/blower panel. It is controlled by a temperature switch and is factory calibrated to 50F. The
heater is used to control condensation problems. This heater should also be energized if the Load
Bank is stored outdoors prior to installation. Refer to schematic diagram for connectioninstructions.
FAN/BLOWER MOTOR CONNECTIONS
The fan/blower circuit consists of fuses, a motor starter contactor, an overload relay, and the fan
motor (one per stack). The input power connections are directly wired to the main Load Bank bus.
Required power for each fan/blower motor is 480V, 3-phase, 60 Hz, 14 amps/phase.
Make sure that the correct phase rotation is wired to the fan motor(s). Improper phase rotation will
cause the fan to run in the reverse direction. The cooling air should be pushed from the fan, across
the resistor elements, and out the top exhaust hood. This phase rotation check is mandatory each
time the source or fan connections are changed. If fan rotation is incorrect, shut down the Load
Bank and remove all power from the Load Bank. Switch any two load cables at the Load Bank load
bus.