ASCO POWER TECHNOLOGIES SIGMA LT 3010 User manual
SIGMA LT Load Banks
User Manual
Revision Number: 5039 - V2.0
Revision Date: 24/6/2020
© NJ Froment & Co. Ltd. This document may not be copied
or disclos ed in whole or part without prior written authority.
© 2000-2020, N J Froment and Co Ltd (‘The Company’).
N J Froment and Co Ltd is part of the ASCO Power Technologies business platform.
Froment and the Froment logo are trademarks or registered trademarks of N J Froment and Co Ltd . All other names and logos referred to are trade names, trademarks or registered trademarks
of their respective owners.
While every precaution has been taken to ensure accuracy and completeness herein, N J Froment and Co Ltd assumes no responsibility, and disclaims all liability, for damages resulting from use
of this information or for any errors or omissions. Specifications are subject to change without notice.
The Company retains exclusive rights to the intellectual property in any designs, specifications, publications and software described or included herein. The property shall not be used in whole
or part for any purpose other than in connection with the Company’s particular products that this document is intended to accompany. The Company’s identification marks on its products and
documents must not be intentionally removed, concealed or defaced. This document may not be copied or disclosed, in whole or part, without prior written authority; any such authority will
include the condition that this copyright statement remains attached.
ASCO Sigma LT load banks are manufactured in the UK by:
N J FROMENT & COMPANY LIMITED,
Easton-on-the-Hill,
STAMFORD,
PE9 3NP,
United Kingdom
Tel: +44 (0)1780 480033
Fax: +44 (0)1780 480044
Web: www.ascopower.com
Sigma LT Load Bank User Manual
Version 2.0 June 2020
Table of Contents
ii
Table of Contents
iii
Introduction
An important note on safety
Chapter One - Introducing ASCO Load Banks
Why is Power Supply Testing Required? 1 - 2
• How can a generator be tested eectively?
• The load bank
Introducing ASCO Load Banks 1 - 4
ASCO Load Bank Control Options 1 - 5
• Sigma LT digital toggle switches
• Sigma LT hand-held
• How do load banks work
Load Bank Applications 1 - 6
• Generating set testing
• Testing UPS systems and batteries
• Data centre HVAC testing
Using Multiple Load Banks 1 - 8
Introducing ASCO’s Sigma LT Load Banks 1 - 9
Sigma LT Load Bank Specifications 1 - 10
Chapter Two - Load Bank Setup
Using a ASCO Load Bank Safely 2 - 2
Transporting ASCO Load Banks 2 - 4
• Lifting by fork lift truck
• Protection and securing on transport
Setting up ASCO Sigma LT Load Banks 2 - 6
• Location
• Setup in a plant room
• Inlet
• Outlet
• Wind eects
• Avoiding hot air re-circulation
Electrical Installation 2 - 8
• Voltage and frequency ratings
• External supply wiring - the fan and control power source
• Connectors
• Supply-on-test - general points
• Is a local isolator required
• Protective earth connection
• Making connections for single phase operation
• Single phase wiring
Control System Connections 2 - 11
Chapter Three - Digital Toggle Switch Control Operation
Before operating the load bank 3 - 2
• Safety warning
Turning the load bank on and o 3 - 3
Introduction to Sigma LT digital toggle switches 3 - 4
Sigma LT digital toggle switches - Quick start guide 3 - 5
Chapter Four - Hand-Held Control Operation
Introduction to the Sigma LT hand-held 4 - 2
• Why network load banks?
• The hand-held
• Symbols key
Sigma LT hand-held screens overview 4 - 4
Setup 4 - 5
Load Control 4 - 6
Load banks in a network 4 - 7
Data Logging 4 - 8
Settings 4 - 9
Status and Events 4 - 10
Table of Contents
iv
Chapter Five - Maintenance & Troubleshooting
Safety Warning 5 - 2
Routine Maintenance Procedures 5 - 3
• Daily (before each use)
• Monthly
• Annually
Fault Finding 5 - 4
Sigma LT Load Bank Status Display 5 - 5
Sigma LT Digital Toggle Switch - Error Messages 5 - 5
Sigma LT Hand-Held Status Display 5 - 6
Sigma LT Hand-Held - Error Messages 5 - 6
Appendices
3020 - Installation Diagrams A - 2
3010 - Installation Diagrams A - 4
3040 - Installation Diagrams A - 6
Certificate of Conformity A - 8
Electromagnetic Compatibility A - 9
Useful Equations A - 10
Introduction
This manual should provide you with all the information that you need to safely setup and operate
ASCO Sigma LT load banks.
The manual is divided into five chapters:
In addition to these five chapters there are a number of Appendices containing information that did
not fit easily within the main body of the text. These include installation drawings, a certificate of
conformity and some information about electromagnetic compatibility.
Chapter One provides an introduction to the general principles of power supply testing
and explains how a ASCO load bank makes the process easier, safer and more reliable.
It then provides an introduction to Sigma LT load banks and its main features.
Chapter Two covers all of the procedures that need to be carried out before a load
bank can be put into operation. It explains how to transport and setup the unit safely
and then how to commission it to check that it will operate correctly.
Chapter Three provides an overview and instructions on correct operation of a Sigma
LT load bank using the digital toggle switches.
Chapter Four provides detailed instructions and reference for controlling a Sigma LT
load bank with the hand-held control.
Chapter Five covers the maintenance procedures you will need to follow to keep a
Sigma LT load bank operating correctly. It also explains how to troubleshoot should a
problem occur.
An Important Note on Safety
All ASCO load banks are designed with safety as a very high priority, but their operation does present
some risks. In common with other test equipment, the safety of all concerned is dependent on the
way that the unit is operated. Do not use this equipment unless you have read and understood this
manual, and are familiar with the accepted practice for the industry. The equipment should not be
used by unskilled personnel. Misuse could result in serious injury and damage to the equipment.
Be sure to follow all of the safety warnings in this manual. In particular, pay careful attention to the
following points:
• Keep all personnel who are not directly involved with tests well away from the load bank and the
equipment under test.
• The discharge air can be very hot and could cause serious flesh burns. Do not touch the outlet
grille while the load bank is running, or for a few minutes afterwards.
• Ensure that there is no risk of the hot discharge air re-circulating back to the air inlet of the load
bank, extensive damage is possible due to short-circuiting the cooling air.
• Ensure the air inlet and outlets are completely unobstructed and that there is no loose paper,
plastic bags, or other debris that may be drawn on to the air inlet grille, obstructing the airflow.
• Combustible material left near the air discharge should be removed.
• Only operate the load bank with all the guards in place and with all of the covers and protective
screens securely in position.
• Make sure that all equipment is adequately grounded; this applies equally to the Supply-on-Test,
and the load bank.
• Ensure all cables are in good condition and adequately rated for the planned load, and that all
connections are securely made.
• Ensure all cables are long enough to lay in smooth curves, and are unstressed, undamaged, and
protected from mechanical damage. Lay the cables to minimise the risk of personnel tripping or
accidentally tugging on the cables.
• Do not switch o the cooling fan immediately after a test. Allow the fan to run for 3 minutes after
removing the load.
• Store the equipment in a clean, dry place when not in use. Only setup and operate the load bank
in environmental conditions suited to the enclosure classification of the load bank.
Chapter One
Introducing ASCO Load Banks
If you are not familiar with the use of ASCO Sigma LT load banks then you should start with this chapter.
It provides an introduction to the general principles of power supply testing and then it explains how a
Sigma LT load bank makes the process easier, safer and more reliable.
If you are an experienced load bank user you may want to skip the earlier sections, but you should
certainly read the introduction to ASCO Sigma LT load banks which appears at the end of the chapter.
Chapter One
1 - 2
Why is Power Supply Testing Required?
There are many dierent ways of generating electrical power and many reasons why
generating equipment may be required. All of them have at least one thing in common: it
is essential that the generator be capable of operating eectively at its maximum rated
output when it is required.
Unfortunately, it is not so easy to be absolutely sure that this will be the case. Many
generating sets operate at a fraction of their rated output for a large proportion of the
time, and many others are intended to run in an emergency situation which may occur only
occasionally.
In both cases the only way to ensure that generating equipment is capable of providing
the performance required is to regularly test it whilst it is operating at its full rated output.
The various regulatory authorities and other concerned parties such as insurance
companies are aware of this, and the testing of new installations is mandatory. In many
cases there is also a requirement for regular testing for existing equipment, particularly
those that provide emergency or standby power supplies.
How can a generator be tested eectively?
The answer to this is very straightforward: apply a load that is equivalent to the generator’s
maximum output and then run the generator and observe how it performs.
The careful measurement of the generator’s output will reveal any problems with its ability
to meet the specification. Then, after repairs or modifications have been made, the test
can be repeated to verify that the fault has been rectified.
The load bank
For reliable testing it is important to provide a load that is suitably sized for the generator’s
output. It must provide a consistent and repeatable load so that the test can be accurately
measured and recorded and it must also be capable of dissipating the large amount of heat
that is generated during the test. And, it is critically important that the test does not put
the site load at risk.
To achieve all this requires a specialist item of equipment: the load bank. These consist
of an array of load elements combined with a control system designed to ensure that a
precise load can be applied in safety.
Introducing ASCO Load Banks
1 - 3
++
++
__
__
AV
How Do Load Banks Work?
Load banks are complex precision engineered machines, but to explain the general
principal we can provide a very simple model of how they work:
Figure 1-1 Basic DIY generator output test system.
Figure 1-1 shows the general arrangement of a very basic DIY generator testing system.
It’s simple, but it contains the four basic items necessary to test a generating set safely:
1. The fan heater’s heating elements provide an electrical load that is large enough to
ensure that the generator runs at full capacity.
2. The fan heater’s switch gear provides a control system that will ensure that the load
can be applied safely, and in a way that will not cause damage to the generator and its
control circuits, or injury to the personnel running the test.
3. The fan in the heater provides a method of safely dissipating the considerable amount
of heat generated by the test.
4. The voltmeter and ammeter provide instrumentation that will allow the results of the
test to be monitored.
Of course, this kind of arrangement can provide only a crude test for a low powered
generator and its ability to match the generator’s output accurately is very limited. As the
output of the generator increases, the cabling, switchgear and control equipment required
for this becomes increasingly heavier and more sophisticated. In addition, because of the
large amount of heat generated during testing, the issue of how to conduct the test safely
becomes increasingly significant.
Chapter One
1 - 4
Introducing ASCO Load Banks
ASCO load banks are purpose designed to provide all of the facilities needed to quickly,
safely and reliably test generating equipment with outputs up to several megawatts.
Figure 1-2 ASCO Sigma LT load bank core components
There are variations between dierent ASCO Sigma LT load bank models, but Figure 1-2
shows a simplified schematic of the core components to be found in most units.
The diagram contains:
• An array of load elements grouped in small steps that are individually activated by
switchgear to allow the load applied to the generator to be precisely controlled.
• A fan and duct forced air system which ensures that the heat generated during testing
is vented safely to atmosphere.
• Fuses and safety interlocks that ensure that the test can be shut down in a controlled
fashion if any problems occur.
• Automatic precision control of the test and allow the results to be displayed with
better than 0.5% accuracy.
Cold air
inlet
Fan
motor
Fan
contactor
Air duct
Step 1Step 2Step n
Hot air
outlet
Load elements
Sigma LT
Digital Toggle
Switch Control
Load
contactors
Fuses
Current
Transformers
External supply for
fan and controls
Supply-on-Test
Sigma LT
Hand-Held
METERING
MASTER
LOAD
5kW 5kW 10kW 10kW 25 kW 50 kW 50 kW 50 kW
REMOTE
LOCALON
MODE
!
V/Hz/kW
Vx 3
Ax 3
LOAD
SELECT
R
ASCO
3000Series
Introducing ASCO Load Banks
1 - 5
ASCO Load Bank Control Options
Reliable testing requires precise control of the load applied to the generator and accurate
real-time measurement of the generator’s output. To achieve this, ASCO Sigma LT load
banks are fitted with a control panel and have the option of a hand-held control. Sigma LT
is a microprocessor-based control and instrumentation system specifically developed for
load bank applications.
Sigma LT Digital Toggle Switches
Sigma LT digital toggle switches are fitted as standard to all Sigma LT Load banks. Digital
toggles provide local, resistive only load testing with single and three phase instrumentation
on a seven segment display.
Sigma LT Hand-Held
The Sigma LT hand-held connects directly to the load bank to provide remote control and
enables up to 25 load banks to be connected into a single network.
METERING
MASTER
LOAD
5 kW 5 kW 10 kW 10 kW 25 kW 50 kW 50 kW 50 kW
REMOTE
LOCALON
MODE
!
V/Hz/kW
V x 3
A x 3
LOAD
SELECT
R
ASCO
3000 Series
399 8 49 9 70 0
Chapter One
1 - 6
Load Bank Applications
The main application for a load bank is usually generator testing. However, load banks are
versatile devices and they have a number of useful applications that can be applicable
including data centre Heating Ventilation Air Conditioning (HVAC) testing and UPS
testing.
Generating set testing
The specific tests that need to be carried out for a particular installation depend on local
regulations, the application, the type of equipment involved and the requirements of
insurance companies, local authorities and other interested parties.
The requirements for the testing of engine driven generators are described in ISO 8528
part 6. This document explains the general test requirements and describes both a
functional test and an acceptance test. Functional tests must always be done and usually
occur at the manufacturer’s factory. Acceptance tests are optional and are often done on
site, witnessed by the customer or his representative.
ISO 8528 part 5 defines three performance classes - G1, G2 and G3, each with dierent
criteria:
• G1 is the least stringent and applies to small generating sets intended to supply simple
loads.
• G2 is broadly equivalent to commercially available power.
• G3 is intended for sets which are powering loads which particularly require a stable
and accurate power supply.
A further class, G4, allows for performance criteria agreed between the supplier and the
buyer.
In addition to the testing that is carried out immediately after installation, it is important
to carry out regular tests as part of an ongoing maintenance program. This is particularly
important for emergency power supplies that may have long periods of non-operation.
The type of tests carried out include:
• Load duration tests (also known as a “heat run”), designed to record steady-state
voltages, frequency, and also to calibrate instrumentation and measure emissions and
fuel consumption.
• Load acceptance tests, which check changes in frequency and voltage regulation due
to sudden load changes. These tests ensure that the rise and fall of the generator’s
output voltage and frequency remain within limits as load is applied and removed.
Note: The specific
details regarding the
frequency and type of
test required may also
be specified by local
regulations or other
interested parties.
Introducing ASCO Load Banks
1 - 7
Testing UPS systems and batteries
Uninterruptable power supply systems consisting of a generating set combined with a set
of batteries are a common feature of data centres and other installations where maintaining
a constant power supply is critical. In the event of a power failure the batteries provide an
immediate source of power whilst the generator is automatically started, synchronised to
the correct frequency and put online.
Regular testing of the batteries, generator and its automatic control gear is extremely
important, but testing using the site load could put critical systems at risk and may not
provide suicient load for a complete test. Load banks provide an ideal solution because
they will allow the operation of the UPS to be fully tested without posing any risk to the
site load.
Data centre HVAC testing
Heating, ventilation and air conditioning (HVAC) systems are vital in providing cooling to
server racks within data centres. The HVAC system must be able to maintain a constant
cool temperature when the servers are working at full capacity. Load banks are a cost
eective method of simulating heat produced by the servers. Operators can analyse how
the HVAC system copes with the temperature rise, without risking the vastly expensive
server racks over heating.
1 - 8
Using Multiple Load Banks
ASCO’s Sigma LT control system allows up to 25 load banks to be interconnected and
controlled from a hand-held as if they were a single unit. This means that multiple load
banks can be combined to match particularly large generating sets.
Figure 1-3 Connecting multiple load banks
An example of a multiple connected load bank application is for an HVAC testing and
verification in a data centre. The networked load banks produce heat discharge throughout
specifically selected areas in the data centre all controlled from a single Sigma LT hand-
held.
Note: When multiple
load banks of dierent
capacities are used the
load applied is shared
proportionally depend-
ing on the ratio of the
load banks’ capacity.
The cable sizes for the
Supply-on-Test must
take this into account.
Total control cable length = 250m
Sigma interface cable Load Bank
1
Load Bank
2
Load Bank
n
Sigma LT
Hand-Held
Supply
under
test
In OutIn OutIn
1 - 9
Introducing ASCO’s Sigma LT load banks
Sigma LT load banks are resistive, portable and indoor load banks. Sigma LT load banks
can be controlled either locally or remotely. The load banks can be linked together in a
network to provide high capacity load tests with the functionality to control a specific load
bank in the network.
ASCO Sigma LT load banks are manufactured with painted or powder coated mild steel,
folded and pop riveted together to form a monocoque construction. Load elements are
cooled by a direct airflow provided by an axial fan.
The input and output ducts are protected by stainless steel mesh screens. All of the
electrical and electronic components are housed behind painted or powder coated mild
steel panels with IP54 protection.
All Sigma LT units are designed to be moved by either built in castors or with a forklift.
For more information about other load banks that ASCO can oer, please contact our sales
team.
Chapter One Introducing ASCO Load Banks
1 - 10
Sigma LT Load Bank Specifications
3010 3020 3040
Nominal capacity (kW) 110 200 400
Standard rated voltage (V) 400 400 400
Terminal qty / phase & size (mm) Single pole Single pole Three pole
Length (mm) 973 1140 1410
Width (mm) 733 870 1040
Height on base (mm) 950 950 1445
Weight, approximate (kg) 150 220 400
Fan(s) - no. x diameter (mm)* 1 x 450 1 x 560 1 x 710
Fan & control current (A) 8 10 10
Airflow direction Horizontal Horizontal Horizontal
* 50 Hz fans only
© NJ Froment & Co. Ltd. This document may not be copied
or disclosed in whole or part without prior written authority.
Figure 1-4 ASCO Sigma LT 3020
Forklift Pockets
Control Panel
Air Intake
Hot air exhaust
Twist Lock
Connectors
External Inlet
Switchgear
Compartment
Power Terminal
Compartment
Chapter Two
Load Bank Setup
This chapter covers all of the procedures that need to be carried out before a ASCO Sigma LT load bank
can be put into operation. It explains how to setup the unit safely and how to check that it will operate
correctly.
Important!
The chapter contains a number of important safety instructions. Do not attempt to setup or operate
the load bank until you have read and understood this chapter. Misuse could result in serious injury and
damage to the equipment.
Chapter One
Chapter Two
2 - 2
Using a ASCO Load Bank Safely
Your safety, and the safety of those around you, is dependent on your knowledge of this
equipment’s safe operating procedures. Load banks can be dangerous and must not be
used by unskilled personnel, or by those who have not familiarized themselves with these
instructions.
You should remain alert to potential danger during transport and setup, when the unit is in
operation, and when maintenance operations are performed.
There are four main sources of danger:
Handling hazards. Load banks are large, heavy devices and they often have to be
manoeuvred in to tight, diicult spaces before they can be setup.
Contact with high voltage electricity. Serious injury or death could result from contact
with electrically live parts. Even though the connections to the load bank may be temporary,
they must always be made to the same standards as if they were permanent.
Contact with fast moving parts. The fan, in particular, can cause serious injury if you
come into contact with it when it is in operation.
Heat hazards. When a test is in progress the resistive elements can glow cherry red. The
heat they produce is removed by the air that the fan forces past them, but that air in turn
can become very hot.
To avoid these hazards, pay particular attention to the following points:
• Make use of the correct handling equipment and ensure that all personnel involved
in transportation and setup have the appropriate training and experience needed to
carry out the operation safely.
• Only operate the load bank with the covers and protective screens securely in position.
• Make sure that both the Supply-on-Test and the load bank are adequately grounded.
• Ensure all cables are in good condition and adequately rated for the planned load, and
that all connections are securely made.
• Ensure all cables are long enough to lay in smooth curves, and are unstressed,
undamaged, and protected from mechanical damage.
• Lay the cables to minimise the risk of personnel tripping or accidentally tugging on
the cables.
• Keep all personnel who are not directly involved with tests well away from the load
bank and the equipment under test.
• The discharge air from the load bank can cause serious burns. Keep away from the
outlet grille while the load bank is running, and do not touch it for at least 10 minutes
after the test is completed.
• Do not switch o the cooling fans immediately on concluding a test. After removing
the load allow the fans to run for a further 3 minutes to dissipate the residual heat. This
will reduce any fire risk and prevent possible damage to the equipment.
• Make sure that the air inlet and outlets are completely unobstructed and that there is
no loose material that could be drawn in to the air inlet grille.
• Ensure that there are no combustible material near the air discharge.
• Keep an approved electrical fire extinguisher present at all times when the load bank
is in operation.
Load Bank Setup
2 - 3
Transporting ASCO Load Banks
ASCO Sigma LT load banks will vary in weight depending on the model. Make sure you
check the load bank name plate for the correct weight. Sigma LT load banks have fork lift
pockets and/or castors. Only lift from the forklift pockets and no where else.
Lifting by forklift truck
Check the specifications to ensure that the forklift truck has suicient capacity to safely
lift the weight. Add 5% to the specified weight for minimum packing, and 15% for a unit in
an export wooden case.
Protection and securing on transport
If a load bank is carried on an open goods vehicle, it should be covered with a tarpaulin, or
a similar to stop the wind from driving the fan.
Figure 2-1 Castor-mounted load banks should be supported o the castors and firmly fixed
down
2 - 4
Note: Do not tie straps
over the top of the load
bank. The tie-down
should be made through
the pockets in the fork-
lift pocket base only.
Castor mounted load banks
should be supported o of the
castors during transport. Use
wooden blocks for this purpose.
Use the forklift pockets to
tie down the load bank
2 - 5
Setting up ASCO Sigma LT Load Banks
There are a number of factors that need to be considered before you select a load bank
for a particular application. Obviously it is important to ensure that the load bank has
suicient electrical capacity to test the supply, but you also need to ensure that it can
operate correctly and safely in the position you have chosen.
Location
The first thing to decide when setting up a load bank is where the unit is to be located. You
need to consider the following to ensure that the unit can be operated safely:
Environment. Sigma LT load banks are designed for indoor use only. A standard Sigma
LT load bank can be used in an ambient temperature between -10°C and +40°C, at 90%
relative humidity (non condensing), and at altitudes up to 1000m above sea level.
Loading. The load bank is heavy and must be setup on a level surface that is capable of
supporting its weight (see nameplate).
Space. There must be suicient space to provide access for maintenance to all of the
panels and the protective inlet and outlet grilles. There must be at least one metre of clear
space on the air intake side of the load bank (the fan side) and five metres of clear space
on the air outlet side. See the appendices of this manual for the specific requirements of
individual units.
Airflow requirements. When it is operating a Sigma LT load bank can require up to 10 m3
of cooling air per second. As it passes through the unit, the air becomes hot enough to
provide a risk of fire or personal injury.
When setting up the unit you need to make sure that there is adequate air available, that
it can be discharged safely, and that there is no risk that the hot air will recirculate to the
air intake of the unit.
Note: If necessary,
a barrier should be
erected around the hot
air outlet to prevent any
possibility of personal
injury.
Warning! Avoid walking
on the roof of the unit.
Chapter Two Load Bank Setup
Setup in a plant room
If the load bank is setup in a plant room you will need to pay particular attention to the
airflow requirements of the unit. The temperature of the surrounding air must not rise
above the maximum rated ambient temperature of the load bank (40°C is standard) and
steps should be taken to prevent re-circulation of the discharge air.
You must take into account the requirements of any other equipment (heating plant,
generating sets, compressors, or another load bank) that may also require a supply of
cooling air. In these cases the total air requirement of all the plant must be added together
to arrive at the required fresh airflow.
The air inlet and air outlet of the load bank must be in the same room, or space.
Inlet
The free area of any inlet grille or opening into the plant room should be at least twice
the area of the load bank air outlet. If other plant in the same plant room requires air,
then the size should be such that the maximum air inlet velocity is below 3m/sec. This
should ensure that the depression within the plant room would always be less than 10Pa,
relative to the outside environment. The distance from the fan inlet to a blank face of a
wall or panel, square to the fan centre line, should be not less than 1m, or one fan diameter,
whichever is the greater.
Attenuators incorporated in the plant room inlet grilles should be sized for a maximum
pressure drop of 10Pa.
Outlet
The outlet opening must have a total free area of twice that of the load bank air outlet, plus
whatever is required for any additional plant.
Wind eects
The load bank must be protected from the eects of the wind, which in some circumstances
could defeat the fan. The inlet and outlet grilles or louvres should preferably be on the
same side of the building. The eect of natural wind is then cancelled out, regardless of
its direction. Other arrangements need careful attention, combined with detailed site and
local knowledge to ensure satisfactory operation in all expected weather conditions.
2 - 6 2 - 7
Avoiding hot air re-circulation
To reduce the risk of hot air re-circulation place air inlets at low level and air outlets at high
level. If this is not possible the inlets and outlets should be spaced well apart. Inlet and
outlet louvres on the same level should have a clear space between them of at least three
times the width of the largest opening. Strategically placed barriers and screens can help
to separate the two air-streams.
Careful consideration should be given to the likely eect of nearby buildings, walls or even
parked vehicles, which could seriously disrupt the free escape of hot air, and result in hot
air re-circulation.
Other nearby air handling plant can also interfere with the airflow to, or from, the load bank.
Equipment should be spaced well apart and positioned so that their airflows complement
each other rather than compete.
When multiple load banks are being used it is important to ensure that the hot air from one
load bank does not exhaust directly or indirectly on to any other load bank.
Packaging
Before starting setup remove all packaging. Dispose of it in the appropriate way.
Chapter Two Load Bank Setup
2 - 8
Electrical Installation
The electrical installation for a load bank consists of making connections both for the
Supply-on-Test and for an external supply that is used to power the load bank’s fans and
control system.
The requirements for the two supplies are described separately here, but the following
general points apply in both cases:
• The work must be carried out by a person with the appropriate training, qualifications
and experience.
• All cables should be appropriately rated and installed in accordance with current
standards and accepted practice.
• The cables for the supply must be sized appropriately and properly fitted terminals
must be used.
Voltage and frequency ratings
Ensure the external supply rating matches the voltage and frequency of the control circuit.
Exceeding the voltage ratings or supplying the wrong frequency can cause damage to the
load bank so please check the plate carefully before setup.
Figure 2-2 Consult the load bank’s name plate for voltage and current ratings
before making connections
Note: The Load Bank
supply cables must be
protected by a Short
Circuit Protective
Device (SCPD), which
is suitably rated to the
capacity of the supply
cables.
2 - 9
External supply wiring - the fan and controls power source
Refer to the load bank’s rating plate for the external power supply requirements. The
supply must be capable of supplying the fan motor starting current, and must be fused
accordingly. Load banks designed to be movable are fitted with an external power input
plug on the outside of the load bank.
Figure 2-3 16A single phase, external power inlet for the fan and control circuit
The load bank is supplied with a 16A external cable coupler. Refer to figure 2-4 for correct
wiring configuration.
Figure 2-4 16A single phase external cable coupler
Connectors
The load bank is fitted with 400A, single pole PowerLock connectors to allow quick
connection and disconnection of the cables.
Figure 2-5 400A, Single pole PowerLock connectors
Chapter Two Load Bank Setup
3
L N
E
2 P + E
(Front on view)
L1 L2 L3 PE
2 P + E
(Side on view)
2 - 10
Supply-on-Test wiring - general points
• It is good practice to route the three phase conductors in a close tre-foil layout, held
together with cable-ties. This minimises stray magnetic fields from the cable array, and
reduces inductive losses in the cables. In the event of a high fault current flowing this
arrangement minimises the risk of sudden and violent cable movements.
• If the connections are made using more than one conductor for each phase connection
all the cables on any one phase should be of exactly the same length, and laid along
a similar route. Ensure that the three phase conductors are equally shared between
multiple cable entry openings, to minimise eddy current losses.
• The load bank supply cables must be protected by the short circuit protective device
(SCPD) which is suitably rated to the capacity of the supply cables.
Is a local isolator required?
When planning the installation consider if a local isolator switch is required. If the output
circuit breaker of the Supply-on-Test is easily accessible, then this can perform the
isolating function.
Protective earth connection
An earth conductor must always be bonded to the frame of the Supply-on-Test and
connected to the grounding terminal of the load bank (marked PE).
Making connections for single-phase operation
3-phase load banks can be used for testing single-phase supplies. The method of
connection (and the load available) will vary depending on the rating of the load bank, the
supply voltage and frequency. Refer to chapter 4 for more information about changing
between single and three phase testing.
Single phase wiring
Single-phase operation is achieved by connection between two phase terminals, one of
which is used as neutral.
A-C connection mode. The A-C connection mode shown in Figure 2-6 will give
approximately 50% loading capacity when the nominal load bank supply voltage is
connected or 17% loading capacity when a single-phase (√3) equivalent supply is used.
Figure 2-6 A-C connection for a single phase supply
Note: If the load bank
is fitted with a 3-phase
fan motor, an external
3-phase mains input will
be required for the con-
trols and fan supply.
L1
L3
L (Live)
N (Neutral)
L1
L2
L (Live)
N (Neutral)
L3
2 - 11
The maximum permissible single-phase supply voltage for this connection is 100% of the
3-phase load bank rated voltage.
AB-C connection mode. The AB-C connection mode shown in Figure 2-7 will give
approximately 66% loading capacity when the nominal load bank supply voltage is
connected or 22% loading capacity when a single-phase (√3) equivalent supply is used.
Figure 2-7 AB-C connection for a single phase supply
The maximum permissible single-phase supply voltage for this connection is 86% of the
3-phase load bank rated voltage.
Control System Connections
Sigma LT load banks all have digital toggle local controls on the load bank. Alternatively
connect the hand-held to the upper connection socket for remote control of the load bank
and to control multiple load banks in a network.
Figure 2-8 The Sigma LT control cable connector.
Sigma LT hand-held
connection socket
Chapter Two Load Bank Setup
Chapter Three
Digital Toggle Switch Control Operation
This chapter explains the local digital toggle switch operation of ASCO Sigma LT load banks. It describes
the functions of the various buttons and displays. For troubleshooting and error message see chapter 5.
Digital toggle switch control operation
3 - 2
Before Operating the Load Bank
Ensure that:
• The load bank has been setup according to the instructions and safety warnings in
Chapter Two.
• The external supply (for fans and controls) is connected according to the instructions
in Chapter Two.
• The supply under test is connected according to the instructions in Chapter Two.
Safety warning
Do not attempt to operate the load until you have read and understood this manual. Misuse
could result in serious injury and damage to the equipment.
• Keep all personnel who are not directly involved with testing the supply well away from
the load bank and from the equipment under test.
• The discharge air can be very hot and can cause serious burns. Do not touch the outlet
grille while the load bank is running, or for a few minutes afterwards.
• Only operate the load bank with all the guards in place and with all of the covers and
protective screens securely in position.
• Ensure that there is no risk of the hot discharge air re-circulating back to the air inlet
of the load bank, extensive damage is possible due to re-circulating the cooling air.
• Ensure that there is no loose paper, plastic bags, or other debris that could be drawn
in to the air inlet, or any combustible material left within range of the air discharge.
• After removing the load at the end of a test allow the fan to run for three minutes to
dissipate the residual heat.
3 - 3
Turning the load bank on and o
The load bank provides a method of quickly starting and shutting down the load bank:
The Fan and Controls Supply Isolator. This is a two position switch which isolates the
power supply to the fan and controls when it is in the o switch. It can be used to perform
an emergency stop, but it can also be padlocked in the o position and this means it can
be used to secure the load bank from unauthorised operation.
Figure 3-1 The Fan and Controls Supply Isolator
Fan and
Internal
Warning! Isolator forfan
and controls supply only.
Other supplies may enter this load
bank. Isolateall before working on
this equipment.
Chapter Three
Warning! Operating
the Fan and Controls
Supply Isolator or Stop
Button does not isolate
the Supply-on-Test
from the load bank
wiring. Some of circuits
within the load bank will
remain live.
3 - 4
Introduction to Sigma LT Digital Toggle Switches
The Sigma LT digital toggles are fitted as standard to all Sigma LT load banks. The control
panel is for local control only and instrumentation is displayed on the seven segment
digital display.
Figure 3-2 Sigma LT digital toggle control panel
MODE. The mode button has three functions.
1. Press mode to cycle through the dierent instrumentation displays: 3 phase
Voltage and Currents or Voltage, Frequency and Power. The LED will illuminate of
the instrumentation selected. (Please note cycling through instrumentation is only
available in 3 phase mode).
2. Press and hold mode for 4 seconds to select single phase (1ph A-C | Conn 1ph
a-C or 1ph AB-C | Conn 1ph a-bC) and three phase (3ph ABC | Conn 3ph abC)
connections. Leave for 5 seconds to select. Ensure the connection mode selected
matches the power connection wiring.
3. Press mode to acknowledge an error if displayed.
LOAD SELECT. The load select buttons have two functions.
1. Press and hold at power up to set the load limit. See figure 3-3. Please note the load
limit selected will be saved.
METERING
MASTER
LOAD
5 kW 5 kW 10 kW 10 kW 25 kW 50 kW 50 kW 50 kW
REMOTE
LOCALON
MODE
!
V/Hz/kW
V x 3
A x 3
LOAD
SELECT
R
ASCO
3000 Series
480 0 59 9 70 0
Mode
Load Select
Metering DisplayError Warning Lamp
Master Load
Local/Remote
Control Selection
Warning! The Fan and
Controls Supply Isolator
does not isolate the
main power wiring from
the Supply-on-Test.
Some of the circuits
within the load bank
will remain live when
the switch is in the o
position.
Digital toggle switch control operation
3 - 5
Figure 3-3 Load limit buttons with load limit amounts.
2. Press any combination of the load select switches to choose the required load in kW.
LED’s will illuminate of those selected. If 30kW is required, press 5kW, 5kW, 10kW and
10kW. Then press master load on. Alternatively if master load is already on there will
be a one second delay then load will be applied automatically. The one second delay
allows a synchronous load change.
MASTER LOAD. Master load applies any load selected when turned on and rejects all load
when turned o. The master load LED will illuminate when on and extinguish when o.
LOCAL/REMOTE CONTROL SELECTION. Switch between local and remote control.
Selected control will be indicated by the illuminated LED. Remote control mode is only
available when a Sigma LT hand-held is connected. Control will automatically switch to the
hand-held when connected.
ERROR WARNING LAMPS. LED lamp will illuminate if an error occurs, the error type will
appear on the metering display. Press mode to acknowledge the error.
Sigma LT Digital Toggle Switches - Quick Start
1. Connect the load bank to a power source and the supply on test (see chapter 2).
2. Turn the fan and controls supply isolator on.
3. Turn the master load switch on. The master load LED will illuminate. If load is applied,
press master load to immediately reject all load on test.
4. Press any combination of the load select switches to choose the required load in kW.
For example, If 30kW is required, press 5kW, 5kW, 10kW and 10kW. Then press master
load on. Alternatively if master load is already on there will be a 1 second delay then
load will be applied automatically.
5. Repeat step 4 to change the load i.e. if the load required is now 20kW press one of the
10kW switches to deselect and after a one second delay 20kW of load is applied. The
one second delay provides a synchronous load change.
6. Press mode to cycle through the instrumentation types.
7. Press master load to reject all load on test.
Chapter Three
METERING
MASTER
LOAD
5 kW 5 kW 10 kW 10 kW 25 kW 50 kW 50 kW 50 kW
REMOTE
LOCALO N
MODE
!
V/Hz/kW
V x 3
A x 3
LOAD
SELECT
R
ASCO
3000 Series
25% 50% 75% 100%
Model
Load Limit
(kW)
Version
Chapter Four
Hand-Held Control Operation
This chapter explains the optional hand-held operation of ASCO Sigma LT load banks. It describes the
functions of the setup, buttons and displays. For digital toggle switch operation see chapter 3 and for
troubleshooting and for error messages see chapter 5.
4 - 2
Introduction to the Sigma LT Hand-Held
The Sigma LT hand-held is an optional method of control for networking load banks. Up
to 25 Sigma LT load banks are able to be connected in a single network. Sigma LT also
provides individual control of any load bank in the network.
Why network load banks?
• Networking allows remote control of the load bank from up to 250m.
• Smaller load banks can be networked for increased capacity, perfect for testing where
a larger load bank would not be suitable i.e. basements and roofs.
• Finer load resolution can be achieved by networking a load bank with small load steps
with larger load banks.
• Redundancy can be achieved by using n+1 load banks. This can be important when
running 24 hour commissioning tests.
The Hand-held
Figure 4 -1 The Sigma LT Hand-held
Chapter Four
4.3” Touch
Screen Display
Cable connection point
USB Port
Aluminium
Enclosure
4 - 3
Key
See below for the list of symbols that will need to be used for operation of the hand-held
control.
Hand-held control operation
Decrease Load
Increase Load
Manual Load Entry
Apply Load
OK
Reject Load
Next Screen
Down Screen
Back Screen
Network Overview
Network Search
Navigation
Other Symbols
Settings
Status - Load O
Status - Load On
Status - Load Warning
Status - Error
Load Selection
Load Bank ID
USB Found
Single Load Bank
Control
This manual suits for next models
2
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