Avtron K711 User manual

AVTRON MODEL K711
LOAD BANK, RESISTIVE, DUCT MOUNT
Serial Number 3118 and Above
©2004 Avtron Manufacturing, Inc. December 29, 2004
Cleveland, Ohio Rev. October 4, 2005

Section Page
I 1-1
II 2-1
III 3-1
IV 4-1
0KW
0 VAC
3 Phase
60 Hz
Amps
0 CFM
Electro Industries - SHARK100 CD-ROM(E145420) & Quick Start Guide(E145703)
(Provided only when Option M or N is purchased)
Schematic/Wiring Diagram, Load Bank
SUPPLEMENTAL VENDOR MANUAL
SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DESCRIPTION AND SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . .
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Outline Drawing, Load Bank
Frequency
Current
Drawings:
Sample Calculations, Engine Generator, Duct Type Load Banks
Bulletins:
202
203
SB2203
Installation Notes, Engine Generator, Duct or Radiator Type
D36481 Schematic/Wiring Diagram, (Controls)
AVTRON MODEL K711
LOAD BANK, RESISTIVE, DUCT MOUNT
K711 - - -
PROJECT NO.
Load Steps
Minimum airflow required for full load operation
Operating Voltage
Load Steps:
Phase
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Total KW
Load Bank Rating:
TABLE OF CONTENTS
BA/kv
10/05/96, 11/26/02 - i -

Table of Contents Avtron Model K711 Load Bank, Resistive, Duct
Mount
• Serial Number 3118 and Above
K711 Options List
These options are available for Avtron Model K711 Load Banks. Not all options can be installed
in the same Load Bank. Installed options are marked on the identification tag.
OPTION
DWG. NO. OPTION DESCRIPTION
C26165 A Remote Control Panel
A20712* B Control Panel Enclosure
D36631-1 C Load Shed, Two Step
D36631-2 D Load Shed, Three Step
D36631-3 E Load Shed, Four Step
D36631-4 F Load Shed, Five Step
C21401 G Outdoor Protection
C21397** H Control Transformer, 208:120V
C21398** J Control Transformer, 240:120V
C21399** K Control Transformer, 480:120V
C21400** L Control Transformer, 600:120V
D36494** M Digital Metering, Local
D36495** N Digital Metering, Remote
* When Option B is installed in Load Bank, Outline Drawing SB1635 is included at the end of
the manual to provide dimensional information.
** When these options are installed in Load Bank, the drawing is provided at the end of the
manual for electrical schematic wiring information.
-ii-

Table of Contents Avtron Model K711 Load Bank, Resistive, Duct
Mount
• Serial Number 3118 and Above
K711 Options List (Cont.)
These options are available for Avtron Model K711 Load Banks. Not all options can be installed
in the same Load Bank. Installed options are marked on the identification tag.
OPTION
DWG. NO. OPTION DESCRIPTION
C22177-H P Controls on Exhaust Side of Load Bank
B29625*** Q Control Panel/Meter Enclosure
D36492-1 R Current Transformers for Metering, 100A
D36492-2 S Current Transformers for Metering, 200A
D36492-3 T Current Transformers for Metering, 400A
D36492-4 U Current Transformers for Metering, 600A
D36492-5 V Current Transformers for Metering, 800A
D36492-6 W Current Transformers for Metering, 1000A
D36492-7 X Current Transformers for Metering, 1200A
*** When Option Q is installed in Load Bank, Outline Drawing SB2196 is provided at
the end of the manual for dimensional information.
-iii-

1-1
AVTRON MODEL K711
LOAD BANK, RESISTIVE, DUCT MOUNT
Serial Number 3118 and Above
SECTION I
SAFETY CONSIDERATIONS
Throughout this manual, you will find WARNING and CAUTION statements. Personal injury to
an operator using or repairing the equipment may occur 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 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 Avtron equipment.
The Model K711 Load Bank is an industrial test unit designed to be used indoors safely. However,
because of the nature of the Load Bank function (the dissipation of electrical energy), there are
inherent dangers to operators and equipment. These dangers are outlined in this section.
The Model K711 Load Bank is designed to be mounted on a duct or on the exhaust side of the
radiator of an engine-driven generator set. The Load Bank resistors rely on the exhaust air from the
radiator fan for cooling.
At design airflow velocities, the Load Bank exhaust air can reach an average 150°F over ambient
with localized parcels of air reaching up to 300°F over ambient. All components of the exhaust air
system must be able to handle this high temperature. There can be no combustible or heat sensitive
devices or equipment inside or near the exhaust duct, including but not limited to the exhaust louvers
and/or shutters.
For supplemental information, refer to Bulletins 202 and 203.

Safety Considerations Avtron Model K711 Load Bank, Resistive, Duct
Mount
• Serial Number 3118 and Above
1-2
Electrical energy is transformed into heat by the resistors. This heat must be removed from the Load
Bank by the cooling blower (not part of Load Bank). If there is any restriction or stoppage of
airflow, the Load Bank may overheat and may even 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, located inside the load
connection area to the generator frame. Run an approved ground wire from the generator
frame to a good earth ground.
3. Your unit is equipped with a temperature switch in the load element area. Do not bypass the
temperature switch to prevent nuisance tripping. The switch drops out load if insufficient air
is reaching the load elements.
4. If the unit is to be installed within existing duct work, leave enough access area to easily
remove access covers on each side of the Load Bank. Special consideration should be given
to mounting surface material, duct and devices in close proximity due to hot air exhaust.
5. Connections to ducts must be watertight in outdoor applications.
6. Maintenance personnel must always exercise caution when the access panels are removed.
Personal injury from electrical shock may resultif all sources of power are not disconnected
before servicing. Maintenance work must be done only by qualified personnel.
7. Adequate airflow in cubic ft./min. (CFM) must be maintained at all times. (Refer to the
DESCRIPTION section for minimum value of required airflow.) Failure to maintain this
airflow evenly across the resistor elements may result in element burnout. Indoor and
enclosed units may require supplemental cooling air. Full load thermal testing should be
conducted on initial run at maximum ambient to verify no cooling/thermal problems exist.
8. If duct work is vented through a screened exhaust or louvered exhaust, ensure that the
louvers (if motorized) are fully open when using the Load Bank. If exhausting through a
screened opening, check screen periodically for any blockage. Screen needs to be a
minimum 75% open area and at least as large as Load Bank core dimensions. The screen
will add additional system resistance to airflow.
9. After running a load test, residual heat may be removed from the Load Bank and
downstream duct work by allowing the blower 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.

Safety Considerations Avtron Model K711 Load Bank, Resistive, Duct
Mount
• Serial Number 3118 and Above
1-3
11. Operators must not operate the Load Bank with the access panels or screens removed. To do
so would expose the operator and other persons to possible personal injury from electrical
shock.
12. An approved electrical fire extinguisher should be on hand at all times.
13. 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.
14. Prior to handling the unit, review the INSTALLATION section of this manual.
15. The Load Bank is designed for maximum 120ºF ambient at 3,000 ft. maximum elevation.
Consult factory if either of these conditions is not met.
16. Standard K711 units which do not include the outdoor (louver) option must have field
installed provisions to protect personnel from coming into contact with load resistor
elements.
17. Read and heed all WARNING and CAUTION statements in the manual.

Description and Specifications Avtron Model K711 Load Bank, Resistive, Duct
Mount
• Serial Number 3118 and Above
2-1
SECTION II
DESCRIPTION AND SPECIFICATIONS
The Avtron Model K711 is designed to be used as a duct- or radiator-mounted Load Bank providing
custom tailored mounting and installation. The K711 provides a resistive load rated as indicated on
the Table of Contents. Minimum airflow required to cool the elements operating at full load is as
indicated on the Table of Contents and must be maintained to ensure safe operation of the Load
Bank.
******************************************************
C A U T I O N
To prevent load element burnout, adequate airflow must be
maintained over the entire load element area at all times voltage is
applied. Insufficient air for even a few seconds will cause element
burnout. This unit must have uniform airflow over the entire outlet
area. If there are dead spots, damage to the elements may result.
******************************************************
CONTROL PANEL
The K711 Load Bank may be provided with a Control Panel as an option or the Control Panel may
be customer supplied. The Control Panel may be supplied by Avtron in one of the following ways:
1. Factory installed on the side of the Load Bank without an enclosure.
2. Factory installed on the side of the Load Bank within an enclosure.
3. Factory installed within a remote mountable enclosure, separate fromtheLoad Bank.
4. Factory supplied without an enclosure for remote mounting.
The Control Panel, when provided, serves as the manual control center for Load Bank operation. All
load switches, safety indicator lights, and control circuit fuses are mounted on the panel.

Description and Specifications Avtron Model K711 Load Bank, Resistive, Duct
Mount
• Serial Number 3118 and Above
2-2
When the Control Panel is not factory supplied, load application and safety circuitry are the
responsibility of the customer.
Each Load Bank is designedwith a relay compartment which contains load contactors, safety circuit
components, optional load step fusing, optional control transformer with fuses, and a customer
connection bus. If a Control Panel is not factory installed, the components in the relay compartment
will require interconnection wiring during field installation of the Load Bank.
Interconnection wiring should conform to the National Electrical Code and any local codes.
DUCT/FLANGE ADAPTERS (K711 ONLY)
Removable duct/flange adapters are provided to assist in the installation of the Load Bank to a
ventilation duct or the exhaust end of a radiator.
1. If required, remove the adapter frame from the Load Bank by removing the hardware that
attaches the adapter frame to the two vertical walls of the Load Bank radiator core opening.
Remove the corner hardware which attaches vertical adapters to horizontal pieces. Also
remove the hardware (if provided), attaching the horizontal adapter pieces to the top and
bottom flanges.
2. Locate and drill holes on the vertical adapter as required to match the duct/flange mounting
holes. (See CAUTION below.) The top and bottom horizontal sections of the adapters are
duct/flange extensions only.
******************************************************
C A U T I O N
The two vertical sections for the duct/flange adapters are the primary
load carrying members. Affix fixture adapters so that load is
transmitted through these vertical sections. Add field installed
supports between Load Bank and a static point as required on units
whenever load carrying capacity of vertical adapters is in question.
******************************************************
3. Reattach the adapter frame to the Load Bank.
4. Mount the Load Bank to the duct or radiator.

Description and Specifications Avtron Model K711 Load Bank, Resistive, Duct
Mount
• Serial Number 3118 and Above
2-3
AUTO TRANSFER SWITCH CAPABILITY
The load control circuitry is factory designed in such a way that remote operation with a customer-
supplied transfer switch may be incorporated into the circuit. The factory control circuitry will be
wired to a terminal board whereas a transfer switch must be enabled and connects at the terminal
board per the schematic.
AUTOMATIC OPERATION
An Automatic Load Shed Controller (Controller) may beintegrated into the control circuitry of the
K711 Load Bank as an option. The Controller is designed to maintain a minimum load on a power
source. A separately supplied current transformer provides the feedback signal required to operate
the Controller. This feedback signal drives the Controller, which has field adjustable current
setpoints. The Controller also incorporates field adjustable time delays to prevent repetitive load
switching or initial overloading of the generator.
The Load Bank manual controls are paralleled by the automatic Controller. Automatic or manual
mode may be chosen when the Load Shed option is provided with the Load Bank.
LOUVERS (OPTIONAL)
The exhaust of the Load Bank may be protected by either a stationary or motorized louver assembly.
Due to exhaust temperatures, a stationary louver is the preferred option.
The motorized version would be added by end users and must include a limit switch whichprevents
the application of load steps if the louvers are not fully open. Verify louver and operating device are
able to withstand exhaust temperatures before installation.

Installation Avtron Model K711 Load Bank, Resistive, Duct
Mount
• Serial Number 3118 and Above
3-1
SECTION III
INSTALLATION
NOTE
The outline drawing needs to be available while reviewing the
INSTALLATION section.
The following steps outline general guidelines for the handling and installation of the Model K711
Load Bank. The first portion of Section III describes the handling (rigging) and physical mounting
of the Load Bank. It is followed by a brief explanation on installing the unit.
It is the responsibility of the installing contractor to ensure all local laws, rules and regulations are
followed for the installation procedure. All laws, rules, and regulations take precedence over this
procedure.
******************************************************
W A R N I N G
To prevent injury or death to personnel, never place any portion of
body under the Load Bank while handling or rigging. These
procedures are guidelines only and do not fully detail the scope of
work required for complete installation. The rigger (installing
contractor) and his equipment must meet all safety and code
regulations.
******************************************************
PREREQUISITES TO HANDLING
1. The Load Bank must be on a level surface at ground elevation. Inspect for damage at time of
arrival. Any damage must be reported to freight carrier prior to acceptance at customer’s
site.
2. Remove shipping crate sides but leave unit on skid.

Installation Avtron Model K711 Load Bank, Resistive, Duct
Mount
• Serial Number 3118 and Above
3-2
3. Verify that all access panels (bolt on panels) are fully secured.
4. There are two methods to handle the Load Bank: Overhead lift using a spreader bar for
hoisting the Load Bank into position or base lifting with a forklift. Installation/rigging
contractor should obtain equipment for one or the other option:
a. OVERHEAD LIFT VIA SPREADER BAR: Use a spreader bar with two double leg
type slings (minimum 3 ft. long). See recommendations on spreader bar below.
b. BASE LIFT VIA FORKLIFT: Use a forklift with forks (tines) at least 36” on center
and adequate lift capacity.
5. End user to provide all mounting fasteners, any supplemental fabricated components, and
supports for installation, if used. Field drilling and or modification to mounting locations are
the responsibility of the installing contractor.
HANDLING THE LOAD BANK
A. Overhead Lift via Spreader Bar
NOTE
A crane with sufficient capacity and lifting height will be required to
hoist the Load Bank from skid (shipping crate) and to raise the Load
Bank for final positioning. Lifting cables, chain slings, and spreader
bar are required and shall be supplied by the rigger. It is
recommended to use a spread bar equal to or slightly longer than the
Load Bank. All rigging equipment should be rated at five times the
basic Load Bank weight.
1. Note the orientation of the spreader bar lifting points should be aligned with the four
1” diameter top flange lifting holes in the Load Bank (see outline drawing). Primary
spreader bar needs to be in line with the Load Bank resistor element section.
Spreader bar is to be parallel to longitudinal direction of the Load Bank frame.
2. Hook up spreader bar to crane and top four lifting points on Load Bank frame.
3. The spreader bar can be used with double leg slings or two cables or chains, each a
minimumof three feet long. Slowly lift spreader bar and verify all slack is removed
evenly from all four slings/cables/chains. If not, lower and readjust as required until
uniform lift is obtained.

Installation Avtron Model K711 Load Bank, Resistive, Duct
Mount
• Serial Number 3118 and Above
3-3
4. Test and verify that the unit is level by lifting the Load Bank. Raise unit up no more
than 6 inches off the ground. Lower and adjust if required to obtain a level lift (level
within 6 inches).
5. The rigger should now attach a guide wire to one corner of the Load Bank for
stabilization.
6. Keep the Load Bank close to ground and position near final lift point.
7. After verification of all rigging, hoist Load Bank vertically and position near final
mounting.
8. Install a support below the Load Bank frame as a safety support. Refer to the
installation notes which follow.
B. Base Lift via Forklift
1. The non-symmetrical design of the Load Bank creates an off-center unbalanced
condition. The Load Bank needs to be supported across the entire base for forklift
handling. Use the shipping crate skid or erect a support base adequate for the lifting
loads encountered.
2. Attach a secondary guide or support bar to boom of forklift.
3. Lift Load Bank less than 3” off ground and check for proper balance. Make any
adjustments as required to adequately support the unit.
4. Position Load Bank near final mounting.
5. Install a support below the Load Bank frame as a safety support. Refer to the
installation notes which follow.
******************************************************
W A R N I N G
When using a forklift, the Load Bank should only be lifted under base
with a skid or secondary support base (supplied by others) to prevent
frame damage.
******************************************************

Installation Avtron Model K711 Load Bank, Resistive, Duct
Mount
• Serial Number 3118 and Above
3-4
MOUNTING THE LOAD BANK
******************************************************
C A U T I O N
The radiator frame or structural supports and mounting hardware
used to permanently mount and anchor the Load Bank must be
designed with sufficient safety factors to not yield under static and
dynamic loading. These dynamic loads include but are not limited to
wind loads, seismic qualification, and any supplemental weight added
to equipment.
******************************************************
This Load Bank is designed for direct installation in a ventilation duct or on the exhaust end of a
radiator. A fabricated Duct/Flange Adapter is provided as noted in Section II. Since radiator designs
vary by manufacturer and size, these flange adapters are not universal. In some cases a custom
fabricated interface between the duct or radiator and the Load Bank is required. If required, custom
fabrication to adapt the Load Bank mounting face to the duct/radiator mounting face is acceptable to
aid installation. This custom fabricated section would be designed, fabricated, and installed by the
installing contractor. Other than this mounting interface, conventional hand tools are required for
installation.
If not using the duct flange adapter provided, the Load Bank should be mounted off the top and
bottom flanges. After mounting, verify adequate clearance between any electrical component and
mounting hardware.
Bulletin 202 shows the proper positioning of the Load Bank in the air duct.

Installation Avtron Model K711 Load Bank, Resistive, Duct
Mount
• Serial Number 3118 and Above
3-5
******************************************************
C A U T I O N
To prevent load element burnout, adequate airflow must be
maintained over the entire load element area at all times voltage is
applied. Insufficient air for even a few seconds will cause element
burnout. This unit must have uniform airflow over the entire outlet
area. If there are dead spots, damage to the elements may result.
Minimum uniform airflow velocity is 850 feet per minute.
Recommended velocity is 1,000 feet per minute across entire load
element area.
******************************************************
In general, the protection provided external to the Load Bank is determined by the local codes.
Since the Load Bank is generally part of an existing electrical installation, it must be protected by a
fused disconnect or circuit breaker meeting all local codes.
Before making any electrical connections, the maximum phase current for the Load Bank should be
determined. This may be done using the following formula.
IPHASE(MAX) = kW x577
V (Line-to-Line)
******************************************************
C A U T I O N
When installing the Load Bank, do not drill into side flanges. Use
factory provided flange adapters or if not using adapters, use only top
and bottom flanges as mounting locations. Compliance with this
instruction helps guard against damage to internal wiring.
******************************************************
The electrical connections necessary for proper operation of the Load Bank are as follows:
1. Connect the load power source as indicated on the Schematic/ Interconnection Diagram.

Installation Avtron Model K711 Load Bank, Resistive, Duct
Mount
• Serial Number 3118 and Above
3-6
2. A ground connection must be made to the Load Bank (GND terminal) to prevent injury to
personnel. This may be accomplished by a ground wire connected directly to the Load Bank
ground stud provided in the control box. This ground wire should be connected to the frame
of the generator under test. The generator frame should be grounded to a good earth ground.
3. Make control circuit connections as required using #14 AWG wire minimum. Refer to the
Schematic Diagram found at the end of this manual for the required control voltage. For
conduit runs greater than 50 feet, consult the factory.
4. When an automatic Controller is included with the Load Bank, installation of the current
transformer on the main power bus as shown in Figure 3-1 is required. Wire the current
transformer into the control circuitry as shown on the provided schematic.
Figure 3-1

Installation Avtron Model K711 Load Bank, Resistive, Duct
Mount
• Serial Number 3118 and Above
3-7
******************************************************
W A R N I N G
Always put a short or shunt across the current transformer when
servicing the Load Bank. Primary current flowing through an
unshunted current transformer will destroy the transformer with
possible harm to personnel.
******************************************************
Never allow the secondary of the current transformer to remain disconnected when primary current
is passing through the transformer. If the Load Bank must be disconnected, put a short or shunt
across the current transformer.
NOTE
Before placing the system into AUTO, place the Load Bank load step
switch(es) to the OFF position.
OPTIONAL CONTROLLER OPERATION AND ADJUSTMENTS
******************************************************
W A R N I N G
Always put a short or shunt across the current transformer when
servicing the Automatic Load Shed Controller. Primary current
flowing through an unshunted current transformer will destroy the
transformer with possible harm to personnel.
******************************************************

Installation Avtron Model K711 Load Bank, Resistive, Duct
Mount
• Serial Number 3118 and Above
3-8
THEORY OF OPERATION
The automatic operation circuitry of the Load Bank allows for a generator to which it is connected to
maintain a minimum percentage of its rated output for efficient generator operation. The control
range is generally between 60% and 80% of the output rating of the generator.
SYSTEM SETPOINT CALCULATION (Example)
System Ratings
Generator Resistive Rating = 375 kW @ 480 VAC, 3 PH.
Load Bank Shedder Capacity: 225 kW @ 480 VAC, 3 PH.
Load Steps: 25, 50, 50, 50, and 50 kW.
Actual Generator Output = Load Bank Load + Building Load.
LOAD BANK ACTUAL GENERATOR
Trip BUILDING LOAD LOAD OUTPUT % OF GENERATOR
Point 0-<75 kW 225 kW 225-300 kW (60%-80%)
TP.1 >,=75-<125 kW 175 kW 225-300 kW (60%-80%)
TP.2 >,=125-<175 kW 125 kW 225-300 kW (60%-80%)
TP.3 >,=175-<225 kW 75 kW 225-300 kW (60%-80%)
TP.4 >,=225-<275 kW 25 kW 225-300 kW (60%-80%)
TP.5 >,=275 kW 0 kW BUILDING LOAD (>,=73%)
At 0 kW building load, the Load Bank will provide 225 kWworth of load. Actual generator output
will be 225 kW (60%) after a preset time-delayed ramp up period.
As the building load increases and the actual generator output approaches 300 kW (80%), the
controller disables one load step; in this example, the last 50 kW load step “sheds”.
This load shed control continues as the building load continues to increase. If the building load
decreases, causing the actual generator load to fall below 60%, the controller will add the
appropriate load step(s) to maintain the desired range of control.
TRIP POINT ADJUSTMENTS
In the system example detailed above, a current transformer having a ratio of 500:5 will be used to
monitor the building load. (Refer to Figure 3-1.) As the actual generator output reached 300 kW,
the controller “shed” a load step. The current flowing to the building load at this point will be called
the current trip point. This “trip point” value can be determined using the following formula:
LINE CURRENT(I(line)) = (kW * 577)/VOLTAGE(LINE-to-LINE).

Installation Avtron Model K711 Load Bank, Resistive, Duct
Mount
• Serial Number 3118 and Above
3-9
In this example I(line) = (75 * 577)/480,
= 90.1 amps
NOTE: FOR SINGLE PHASE SYSTEMS:
I(LINE) = WATTS/VOLTAGE(LINE-to-LINE).
Secondary Current Calculation
The controller senses the current (Isense) delivered from the current transformer that is monitoring
the building load. This value can be determined using the following formula:
I(sense) = I(line)/ CT Ratio.
In this example, the CT Ratio = 500/5 or 100.
For TP.1 I(sense) = 90.1/100 or .90 amps ( 75 kW)
For TP.2 I(sense) = 150 /100 or 1.5 amps (125 kW)
For TP.3 I(sense) = 210 /100 or 2.1 amps (175 kW)
For TP.4 I(sense) = 270 /100 or 2.7 amps (225 kW)
For TP.5 I(sense) = 331 /100 or 3.3 amps (275 kW)
Adjustments can be made to the PC board controller via the adjustable resistor potentiometers found
on the PC board. (Reference resistors labeled LEVEL PERCENT, R73, R60, R47, R34, and R21.)
NOTE
R73 controls the last load step circuit. (i.e., if the Load Bank has five
load steps, R73 controls the fifth load step.)
The potentiometers should be adjusted such that the last load step is the first step to be “shed”. On
the Controller, there is an LED indicator for each channel (Output). When lit, the channel is
energized.
In this example, R73 = TP.1 Channel 5 (LED CR29)
R60 = TP.2 Channel 4 (LED CR25)
R47 = TP.3 Channel 3 (LED CR21)
R34 = TP.4 Channel 2 (LED CR17)
R21 = TP.5 Channel 1 (LED CR13)
The “trip point” value = I(sense) can be applied to the controller terminals J1 and J2 using a separate
current source.

Installation Avtron Model K711 Load Bank, Resistive, Duct
Mount
• Serial Number 3118 and Above
3-10
There are two methods of field adjusting the trip point of the current sensing relays:
Method 1 - Using a separate (0-5 amp) current source without the current transformer
Method 2 - Rough adjustment (Approximation Method)
Method 1 - Using a separate (0-5 amp) Current Source without Current Transformer
1. Disconnect all sources of power to the Automatic Load Shed Controller (control voltage and
current sense input).
******************************************************
W A R N I N G
When disconnecting the current transformer, the secondary terminals
must be shorted. The secondary of an unshorted current transformer
can exceed several thousand volts.
******************************************************
2. Apply 120 VAC, 60 Hz control power J1(10-12) (see schematic).
***************************************************
W A R N I N G
There is lethal high voltage within the control enclosure.
***************************************************
3. Using a controlled current source, apply the setpoint current (from secondary current
calculation) to Controller terminals J1(1) and J1(2).
4. Turn the adjustment potentiometer labeled LEVELPERCENTcounterclockwise pastthetrip
point; then decrease until the channel trips on, indicated by LED illuminating.
5. Reconnect all wires previously removed.