Select a Rack Mounted Load Bank by matching its usable power at the actual supply voltage to the intended rack load, then confirming that its airflow and physical arrangement represent the planned equipment. A kilowatt rating alone cannot establish suitability. The selection also needs to account for rack space, electrical connections, load increments, inlet conditions, and the cooling system’s ability to remove heat throughout the test.

Start with a defined test condition: the heat load per rack, the number of racks operating together, and the airflow path being commissioned. Distinguish the initial deployment from the highest planned density. Equipment sized for the initial installation can leave the cooling system untested at its eventual operating point; oversized equipment with coarse load steps can make the initial condition difficult to reproduce.

Define the rack load before choosing capacity

Use the intended electrical consumption of the rack as the starting point for heat generation. For equipment operating within an air-cooled rack, nearly all consumed electrical power ultimately becomes heat. The relevant target is therefore the planned operating load, rather than the sum of power-supply nameplate ratings, which can substantially exceed actual consumption.

Keep three values separate: normal operating load, the highest load included in commissioning, and installed test capacity. Installed capacity must support the highest test point after accounting for supply voltage, ambient limits, and any operating restrictions. Additional capacity is useful only when the available load steps still permit accurate operation at lower test points.

For example, if an illustrative commissioning plan includes 12 kW and 18 kW rack conditions, the selected equipment must reach both values at the available voltage. A nominal 20 kW unit does not automatically satisfy that requirement. Its rating could apply to a different voltage, or its load increments could prevent an exact 18 kW setting. State these test points explicitly in the equipment specification.

Room-level testing introduces another constraint. Ten racks operating at the same load produce a different airflow distribution from the same total power concentrated in fewer racks. When validating rack density, preserve the intended spatial distribution instead of relying only on aggregate kilowatts.

Rated power changes with the electrical connection

For a fixed resistance, power follows P = V²/R. A reduction in applied voltage therefore reduces heat output unless the equipment has a switching arrangement or control system designed to maintain the requested power. Obtain the available load capacity and step schedule for the exact voltage and connection configuration used during the test.

As an illustrative calculation, a fixed-resistance element rated at 230 V would produce approximately 82% of its rated power at 208 V, assuming unchanged resistance. This relationship describes the element; it does not establish the behavior of a complete assembly with alternative element connections or regulated loading.

The electrical supply must support the selected load at the rack connection. For a balanced three-phase resistive load, current is approximately I = P/(√3 × V_LL), with power in watts and line-to-line voltage in volts. For a single-phase resistive load, use I = P/V. Include auxiliary consumption where it affects feeder loading, particularly when fans and controls use a separate supply.

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