Resistive Load Banks
Load Modules
Resistive Load Modules
Reactive Load Banks
Control Systems
Manual or Computer Control
RESISTIVE LOAD BANKS 2kW - 3500kW
RATINGS
All standard Crestchic Load Banks are rated for continuous
operation in ambient temperatures up to 35ºC, tropicalised
versions are availabLe for operation at higher temperatures.
Resistive load banks can be manufactured to any size at any
voltage and frequency to suit customers requirements.
A standard range of load banks with ratings between 2kW and
3500kW at customers specified voltage and frequency are
available in standard frame sizes.
Resistive load banks are not effected by change in frequency
but must not be operated at voltages above the specified
voltage. They may however be used on lower voltages, but the
total load available will be proportionaLly reduced.
When operating at reduced voltages or at frequencies other
than the specified frequency the cooling fans and control
circuits will require the connection of a suitable external
auxiliary supply.
Standard resistive load banks with ratings up to 1600kW are
available in folded steel encLosures, larger banks with ratings
up to 3500kW are buiLt in ISO type containers.
ENCLOSURES
Folded steel and ISO container type enclosures are both
available in two forms, one designed for fixed installation at
permanent outdoor locations, the other transportable for
moving from site to site.
Both types give 1P55 protection and have overhead lifting
facilities.
RESISTIVE ELEMENTS
Totally enclosed tubuLar stainless steel elements switched in
groups of various values by contactors provide a variable
resistive load with a 1kW resolution.
The elements are mounted inside an element chamber isolated
from other equipment and cooled by forced air from motor
driven fans.
The fans are controlled by DOL starters with thermal overloads
and electricaL interlocking which prevents load from being
applied unless fans are running.
Thermal sensors will shed all load if the temperature inside
the element chamber exceeds a safe limit.
Air flow sensors are fitted on units rated above 400kW to
proted against Loss or reduction in airflow.
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100kW TRANSPORTABLE
200kW FIXED
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Load Modules
Crestchic Load Banks are available in two forms, Resistive and Reactive, and are designed to produce a controlled, variable AC load for commissioning, periodic testing or load management of generators and UPS systems.
SELECTING THE CORRECT LOAD TO SUIT YOUR APPLICATION
Where the load is required for carrying out regular periodic testing of generators a resistive load is normally used, this being adequate to prove the output of the engine, transient and steady state performance of the governor and installation temperature rises. However, when commissioning includes parallel operation of two or more generators then reactance and resistance is needed to produce a lagging power factor load in order that the test engineer may adjust and verify the automatic sharing of both active and reactive components of the load.
Where 'load management' is needed on a diesel generator, to prevent damage to the engine caused by low load operation, a resistive load is normally used with manual or fully automatic control to maintain an adjustable minimum load on the generator.
Testing UPS systems and type testing alternators requires resistance and reactance to produce a lagging power factor load which can be fixed at 0.8 pf lagging or variable between a specified figure and unity.
TYPE OF LOAD
Reactive load can be supplied as stand-alone modules for use with resistive units or combined with the resistive load into a single module.
Standard Resistive AC load modules are available in six frame sizes with ratings between 10 kW and 1200 kW, as defined in Table 1. These are manufactured for operation on a single voltage and frequency specified by the customer when requesting a quotation. Units suitable for use on dual or multiple voltages and frequencies can be quoted on request.
Both Resistive and Reactive units are available for fixed installation, transportable with castors or with the option of road trailers.
SPECIFYING THE LOAD
In order to supply the correct load for your application the following minimum information is required:
RATING
VOLTAGE AND FREQUENCY OF SUPPLY
TYPE OF LOAD, RESISTIVE, REACTIVE OR COMBINED
FIXED OR VARIABLE POWER FACTOR
FIXED INSTALLATION OR TRANSPORTABLE
Having specified which type of load is required the customer must now decide which method of control is best for his application. Three types of control systems are available together with a range of controllers, all of which are described in the control section of this Brochure.
Resistive Load Modules
RATINGS
All standard modules are suitable for continuous operation at the specified ambient temperature.
Standard resistive AC load modules are available in six frame sizes with ratings between 10 kW and 1200 kW. The maximum amount of load available in any frame size is dependent on the capacity of the cooling fans and the number of resistor elements needed to give the required switching resolution.
Standard Units are designed for operation at a specified voltage and frequency. Multi-voltage, multi-frequency equipment can however be manufactured to order.
The load resistors are unaffected by change in frequency but must not be operated at voltages above the specified voltage. They may however be used at low voltages, but the total load available will be reduced.
When operating at reduced voltages the cooling fans and control circuit will require the connection of a suitable auxiliary supply.
Standard ratings are shown in Table 1.
ENCLOSURES
Enclosures are manufactured from coated mild steel sheet, folded to form a rigid IP55 construction.
Transportable models are suitable for lifting by forklift truck and are fitted with heavy duty swivel castors and lifting eyes.
When ordered for fixed installation the castors are replaced with channels for fixing to a suitable concrete base.
The standard finish is a white, oven-baked, polyester powder coating which gives a tough high gloss finish resistant to UV radiation. For installations in a corrosive or salt laden atmosphere special finishes are available.
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CONTROL
The resistors are switched by contactors in order to supply a 1kW switching resolution for all ratings up to 1200 kW.
The integrated control PCB accepts signals from any of the Crestchic controllers, each of which is designed to perform a particular control function.
More than one load module may be linked by a control loop cable and operated as one load by a single controller, this facility is available as an option.
When required by the customer, simple on-board control can be fitted to switch the load in a limited number of steps by means of toggle switches or externally by customer's own control system.
Full details of the various controllers and control systems are given on pages 6 - 8.
COOLING
Crestchic standard load modules have forced air cooling suitable for operating in ambient temperatures up to 35 deg.c. Tropicalised versions are available allowing operation in higher ambients.
The air flow on transportable units up to 400 kW is produced by single phase motor driven fans, larger units and units for fixed installation have 3 phase motors.
Fans are controlled by DOL starters and protected by thermal overloads.
Thermal sensors will shed load should the temperature of the element chamber exceed 90 deg.c. Airflow switches are fitted on units rated in excess of 400 kW.
Stayput emergency stop push buttons are fitted to the fan circuit.
Transportable modules with 3 phase motors have a monitor circuit to prevent operation unless phase rotation is correct. Optional manual changeover switch or automatic changeover contactors are available to correct the phase rotation.
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Reactive Load Modules
CONTAINERISED MODULES
LOAD RANGES
The standard containerised module produces up to 3.3MVA, 0.8 Power factor, at 480 V 60 Hz and may be used on lower voltages at both 50 Hz and 60 Hz at reduced capacity.
Non-standard modules can be manufactured to meet any specified voltage and frequency up to 3.3 MVA at a maximum 480V within the same module dimensions.
Larger loads and high voltage systems can be supplied to meet customer's specifications.
CONTROL SYSTEM
The containerised load modules are operated by the MCS control system. Details on pages 7 & 8.
ENCLOSURE
The enclosure is constructed in the style of a standard 10ft ISO container and finished with a corrosion resistant paint.
Internal access is by large double doors at one end with control and main cable connections behind separate doors at the opposite end. Trailer mounting is an option.
RESISTIVE LOAD
Resistive load is supplied by totally enclosed elements manufactured from 80/20 nickel/chrome resistance wire centred in stainless steel tubes filled with compressed magnesium oxide. The exterior of each tube is fitted with a stainless steel cooling fin.
Elements are mounted in a chamber with terminals passing through a bulkhead into the switching section by means of compression glands so separating electrical connections from the cooling air.
The elements are arranged in groups of various values and switched in steps by contactors.
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REACTIVE LOAD
Reactive load is supplied by air cooled iron cored 3 phase rectors of various values switched by contactors.
COOLING
Cooling is by eight axial fans mounted in groups of four either side of the enclosure. Cold air is drawn through weather louvres in the side and exhausted through grilles in the roof of the enclosure.
Phase rotation relays and automatic changeover contactors ensure correct direction of airflow.
AUXILIARY SUPPLY
Each load module is fitted with the option to power the cooling fans and control circuits from the main bars or an external 3 ph supply.
SHIPPING DETAILS
Height: 2591mm
Width: 2438mm
Length: 2991mm
Weight: 10500kg
NON CONTAINERISED MODULES
Non containerised Load Modules are manufactured from 2mm zintec coated mild steel folded and welded to form a rigid construction and finished in a white oven-baked polyester powder coating.
Modules up to 400 kVA can be castor mounted but larger sizes should be either for permanent installation or mounted on a trailer.
The Resistors and Reactors are the same specification as for the containerised modules but the cooling air flow is horizontal.
Modules requiring variable power factor control must be operated by the MCS range of controllers, For a single voltage and fixed power factor the ACS system may be used.
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CONTROL SYSTEMS
1600kW Transportable in ISO Container
600kW Transportable
1200kW on Optional Trailer
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Crestchic Load Banks can be supplied with any one of the following five standard control systems:
Each control system has been carefully designed to meet a particular range of applications.
Basic Control
Provides the simplest form of control where Load is required to be switched in a limited number of fixed steps to provide manual Load test or dummy loading. The Load steps are switched by contactors, the coils of which are controlled by simple on/off toggle switches mounted on the load bank or are wired out to terminals for incorporation into customers own control system.
KCS Control
The most commonly used of the five types of control, this manually operated pcb mounted system is used where accurate
local or remote manual control is required.
Consisting of decoder and driver cards mounted in the load
bank, the system can be supplied with any one of three types of
control terminal; local, remote or hand-held. Each allows loads
to be selected and applied with a 1kW switching resolution.
MCS Control
The MCS control system is used when automatic programmable
control and instrumentation is required.
The sophisticated computer control system consists of a
Crestchic designed micro processor and a choice of remote
control terminals.
The micro processor inside the load bank carries out all
computing needed for calculation and control of complex loads,
measurement and storage of data.
Control instructions are entered via a keyboard and data is
displayed on the screen of the control terminal.
Baseload Control
A low cost system designed to ensure that a generator never
runs below a preset minimum load.
Load is switched in one or two steps by contactors controlled
by a PCB mounted controller monitoring the 5 amp secondary
of a current transformer installed in one phase of the generator
output.
Load Trakker Control
Like the Baseload control this system is also designed to ensure
that a generator is never run below a minimum load level,
however, unlike the Baseload control system it uses a micro
processor based system constantly adjusting the load in 1kW
steps to maintain the preset minimum and can also be used to
manually control the load bank allowing it to be used for
conventional testing.
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Control Systems
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Crestchic Load Modules are supplied with one of three control systems; the BASIC, the ACS or the MCS.
BASIC SYSTEMS
The Basic system provides the most simple control available whereby the operating coils of the load contactors are wired out to terminals for customers control or are switched by on/off toggle switches mounted on the module.
ADVANCED CONTROL SYSTEM-ACS
The ACS system is used with single voltage and frequency load modules where accurate manual control is required without the micro processor intelligence needed to carry out the calculations associated with control of multi-voltage/frequency loads.
A set of decoder and driver cards, forming the ACS control system, is mounted inside the load module where they control the switching of the load contactors.
SYSTEM LOAD CAPACITY
Used ins resistive modules with ratings up to 1200 kW, reactive modules up to 900kVAr and combined resistive/reactive fixed 0.8pf loads up to 1500 kVA. The ACS system gives full control allowing them to be switched in steps of 1kW (1kVAr on reactive units).
Where required an extension board can be fitted as an option to allow two more modules to be operated as a single load from one controller so increasing the capacity available.
LOAD APPLICATION
The ACS controllers use 2,3 or 4 digit indexing switches with enter and clear push buttons to select and apply the desired load. Once applied the value is retained allowing the switches to be reset. Operation of the enter button will then increase or decrease the load to the new value displayed.
INSTRUMENTATION
Instruments can be fitted as an option mounted locally on the module or on the remote controller.
ACS CONTROLLERS
Any one of the range of ACS 100 controllers can be used with the ACS system.
ACS100L
Full control in steps of 1kW allows the operator to set load to any value between zero and full load. Operating range up to 1200kW or 900kVAr. The indexing switches are mounted on fascia of load module.
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ACS100H
Full control in steps of 1kW allows the operator to set load to any value between zero and full load. Operating range up to 1200 kW or 900kVAr. Indexing switches are mounted in hand held ABS enclosure with a 10 metre flexible control cable.
ACS 100R
Full control in steps of 1 kW allows the operator to set load to any value between zero and full load. Operating range up to 1200kW or 900 kVAr. Indexing switches supplied on flange plate for mounting on customer's panel.
ACS100D
Exactly as the ACS100R controller but fitted with the facility to switch load to zero upon receipt of a mains failure signal from customer's detector so preventing possible over-loading when automatic changeover contactors operate.
ACS100 TRAKKER
Used in conjunction with a suitably rated current transformer, positioned in customer's switchgear so as to monitor the site load. This control system automatically maintains a preset minimum load on a generator regardless of changes in the site load. Ranges up to 1200 kW.
Indexing switches mounted in 19" 3U high racking for mounting into customer's cubicle.
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Control Systems
COMPUTER CONTROL SYSTEMS-MCS
The computer control system consists of a custom built micro processor mounted in each Load Bank, a control terminal and a printer. The Load Bank processor is responsible for the actual calculation and control of the applied load, measurement of variables, storage of PRESET LOAD data and calibration constants.
The terminal is used to provide the operator interface displaying all relevant data whilst the load is applied and allowing control of the system through a series of user friendly menus.
The terminal can be sited at a distance from the Load Bank, for example, in the control room of the equipment under test.
SYSTEM LOAD CAPACITY
The micro processor fitted to the Load Bank has the capacity to control resistive, reactive or combined loads up to 6MVA. Additional Load Banks may be added to the system using a RS485 link.
These may be of any size up to 6 MVA but the system must not exceed 15 modules.
When a load is selected on a multi-module system it is applied in proportion to the size of each separate module.
Where no auxiliary supply is available to power the cooling fans they can be fed directly from the supply under test.
Under these circumstances the system measures the actual `standing load' drawn by all of the cooling fans and integrates it into a component of the applied load.
START UP
Providing power to the auxiliary circuits will initiate the communication routine `AUTO TEST' indicating the maximum potential load connected or identifying errors.
Pressing 'LOAD MODULE START' function key will display 'WAITING FOR LOAD BANKS TO COME ON LINE' and the cooling fans will start up in sequence.
Any failure to start will be identified and 'SYSTEM HALTED' displayed.
Should there be a fan failure or over temperature alarm after start up, the display will read 'PRIORITY ALARM'.
A satisfactory start up will display the first operator's menu.
SHUT DOWN
A stop function key is provided to initiate a controlled shutdown with a duration of three minutes, during which time the fans will continue running to cool down the load.
The shutdown can be aborted at any time during the three minute period and the system automatically restored to the operator's menu.
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LOAD APPLICATION
Four options are available:
- Keypad Loads
Entered as Amps and power factor, may be altered without returning to zero.
- Manual Presets
Up to 20 presets may be used and are entered individually as a percentage of the generator full load kW at any specified power factor. The presets may be entered in any order.
- Auto Presets
The presets are prepared as for the manual mode but with the addition of duration in hours,
minutes and seconds.
A range of presets are selected and once initiated the programme will run automatically until
completed.
- Search Mode
In search mode the load can be freely manipulated by the operator.
The size and power factor of the load is adjusted using the arrow keys and can be stored for repeat applications.
Load may be removed at any time by pressing 'ESC'. key.
It is also possible to reduce load at the rate of 25% of the displayed value by the operation of a function key.
INSTRUMENTATION
The target load and power factor are displayed on the terminal screen together with elapsed time and the following data:
Measured voltage
Measured power
Measured load current
Power factor
Measured frequency
The displayed information can be recorded on a standard parallel port printer together with 'Transient Capture' voltage and frequency at each load change.
Not available on HHT100B.
DYNAMIC ADJUST
This unique facility developed by Crestchic Limited compensates for inaccuracies in the applied load due to component 'production spread' and/or voltage drop. Adjustment may be at the operator's discretion or automatic. The adjusted load may be 'Learned' by the system for a repeat test.
Not available on HTT100B.
'M' TEST
Provision is made for the addition of a low power factor load to be added to any of the presets. This feature is particularly useful when testing marine generators.
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Control Systems
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TERMINAL OPTIONS
HHT100B
Full micro processor control of load modules of any value, the hand-held terminal provides automatic calculation of load components needed to produce the required load at a voltage and frequency entered by the operator.
Back-lit LCD display screen.
Keypad selection and application of load
Storage of up to 20 preset loads.
Automatic timed sequencing of preset loads to provide a profile of load changes.
M-Test facility.
10 metres RS232 communications cable.
HHT100F
As HHT 100B but with the addition of an instrumentation card, current transformers and transducers to take full advantage of the capabilities of the micro processor.
Display of measured values during test.
Capture and display of max transient Voltage and frequency excursions during load changes.
Dynamic adjustment of load to compensate for Voltage drop or component drift.
Storage of learned dynamically adjusted loads.
Free manipulation of kW and power factor by use of raise and lower keys with facility to learn and store the final result.
Output port, located on load module, for connection of printer to produce printout of test results whilst on load.
NCC100T
Providing all the features of the HHT100B terminal but with an industry standard notebook computer providing the enhanced facilities of a mono VGA screen and an output port to drive the printer.
PCC100C
Providing all the features of the NCC100T but using a desktop PC with colour VGA monitor and standard keyboard.
PCC 100S
Software only for installation onto customers own compatible computer, the software package provides all the features of PCC100C.
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HHT100
Hand held IP65 terminal with 8 x 20 character back lit LCD display, custom built keyboard with 10 function keys, 0-9 keys enter, clear, raise and lower keys, 10 metre communication cable using RS232 for data integrity.
NCC100T
Industry standard PC notebook computer with standard keyboard, mono VGA screen and 10 metre communication cable using RS232 for data integrity. Mounted in protective aluminium case.
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