Applications for Movable Load Banks
Background Information
Load banks are used to test power sources and distribution systems to verify the performance and regulatory compliance of power sources; ensure that minimum operating load requirements for power sources are met; test facility backup power systems without using live building load; or to adjust power factor. At many facilities, the use of load banks will occur regularly over long periods of time and static load banks are installed for this purpose. Examples include factories that must test the electrical equipment they produce, laboratories that regularly apply electrical load for test or research purposes, and mission-critical facilities that must regularly test backup power systems to verify their readiness for service during utility power outages.
For other facilities, the scope of load bank use may be limited by the nature of a facilities activities or a need to use load banks only at certain times. One example – a facility that needs load banks only for annual testing or calibration of systems, or at the commissioning of a building and its equipment. Likewise, a testing or equipment rental business needs to relocate load banks often. This article reviews five applications where moveable load banks are used.
Application 1: Load Banks Must Be Conveniently Transportable by One Person
“Suitcase-style” load banks offer the smallest and lightest form factor. These small load banks typically weigh less than 100 pounds (45 kilograms), are enclosed in a case, and fitted with a handle and wheels. Not unlike a technician’s toolkit or a traveler’s airline luggage, they are readily moveable by one person and are easily transported from location to location.
Offering typical capacities of 10 to 100 kilowatts (kW), these are suited for testing discrete equipment and smaller loads. They fit in small workspaces, such as narrow equipment aisles, or in irregular spaces that limit access to larger units.
Avtron Model 2500 and Model 2600 load banks represent the type. They each apply resistive load to three-phase systems, and the 2600 can also be used for single-phase applications. Each requires 120-Volt AC control power. Figure 1 includes an Avtron Model 2600 load bank.
Application 2: Doors or Elevators Restrict Equipment Size
In order to adequately load equipment or systems under test, some facilities will require larger loads than suitcase-style units can apply. Nevertheless, the equipment may have to move through narrow doorways or elevators to reach the test location, such as a backup generator on a rooftop.
Load banks on four casters offer an easy solution for these facilities. Weighing up to several hundred pounds or kilograms, these units are readily moved into delivery vehicles, through doors and loading docks, and to work locations inside buildings. Many models within Avtrons 2000 SERIES and 3000 SERIES are caster-mounted and offer ratings from 100 through 700 kW for three-phase applications. Multiple units can be operated from a single networked control system to meet the functional and capacity needs of the application. The Avtron Model 2805 load bank shown in Figure 2 is an example of the type.
Application 3: A Larger Load Bank Is Needed and Must Remain Movable
As the weight of load banks increase, it may become necessary to move them using a forklift. Channels for forklifts are clearly visible in the frame of the Avtron Model 3024 shown in Figure 3.
Application 4: A Load Bank Must Be Frequently Transported Between Sites
A testing or equipment rental firm will regularly transport load banks between sites. Some load bank users may likewise desire to transport load banks between their facilities, such as a network of cellular telecommunication sites. For these applications, trailer-mounted units can be easily delivered to and retrieved from sites.
Trailerable units are also a solution for facilities that may not have a permanent generator. By installing a quick connect panel and a permanent switching means, facilities can readily connect a generator that is transported to and left at their site. This can also help facilities comply with NEC requirements to provide a “backup-for-the-backup” when a facility’s sole permanent generator is taken offline for service.
As an example, the Avtron 5000 SERIES offers trailer-mounted load banks with ratings up to 3000 kW. The Avtron Model 5830 is an example of the type. Rated at 3000 kW, it is shown in Figure 4.
Application 5: An Outdoor Load Bank is Needed to Test Very Large Loads or High Voltage Applications
Containerized load banks are available in 10, 20, and 30-foot shipping containers constructed to ISO standards. Because they are standard sizes, they can be shipped by common carriers. Because they have ISO-specified lifting features, they can be readily rigged and set into place. Advantages of this type can include:
- Protection of equipment against elements of weather
- A control room that protects operating personnel from weather
- Rugged construction that protects units from the effects of repeated transport and handling
- Ratings for large low voltage loads
- Transportable medium voltage models
Avtron containerized, low-voltage, resistive/reactive load banks are available with ratings up to 6000 kVA and 480 Volts. Medium voltage containerized models are available to 5000 kVA and 24,000 Volts.
Summary
There are at least five reasons for using a moveable load bank to test or adjust electrical loads at commercial, industrial, healthcare, telecommunication, and data center facilities. These include:
- load banks must be conveniently transportable by one person
- doors or elevators restrict equipment size
- a larger load bank is needed, and must remain movable
- a load bank must be frequently transported between sites
- an outdoor load bank is needed to test very large loads or high voltage applications
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