The BK Precision MDL4U Series is a multi-channel modular programmable DC electronic load system designed for testing a wide range of power sources. The platform consists of the MDL4U001 mainframe with a built-in controller and four open slots, populated with any combination of seven available load modules ranging from 200 W to 600 W. A single mainframe accepts up to 2400 W of load capacity, and the MDL4U002 mainframe extension expands the system to 4800 W and up to 16 channels when dual-channel modules are used.

The MDL4U Series is built for testing multi-output DC power supplies, batteries, fuel cells, and photovoltaic arrays. All modules operate in constant current, constant voltage, constant resistance, and constant power modes, supporting both steady-state characterization and dynamic loading. Transient mode operation enables periodic switching between two load levels to evaluate power supply regulation and transient response, while list mode supports more complex multi-level input sequences for waveform-driven test scenarios.

ValueTronics is a B&K Precision authorized distributor and supports MDL4U Series customers from our 20,000 sq ft facility at 1675 Cambridge Drive in Elgin, Illinois. Each {{CONDITION}} MDL4U mainframe, extension, and load module is inventoried, prepared, and shipped from Elgin, with technical resources available to help configure module combinations against the specific voltage, current, and channel-count requirements of an application.

Brand Heritage

B&K Precision was founded in 1951 and has operated under that brand name continuously, providing test and measurement instruments for more than 70 years. The company's European operations are conducted through its French subsidiary Sefram, and Asian operations through B+K Precision Taiwan.

Compare Other Models in This Series

The MDL4U Series is organized around a common mainframe and extension architecture populated by seven interchangeable load module types. The MDL4U001 mainframe contains the system controller, four module slots, and the front-panel keypad, VFD displays, and adjustment knobs that drive each installed module. The MDL4U002 mainframe extension provides power and connectivity for an additional four module slots, doubling the system's module capacity when connected to an MDL4U001.

Module selection determines the voltage range, current range, power rating, and channel count of each slot. Single-channel modules range from 200 W to 600 W and cover input voltages of either 80 V or 500 V, while two dual-channel modules (MDL4U252 and MDL4U302) distribute their total module power between two independent channels. All modules share the same 3.2 × 6.7 × 22.6 inch single-slot form factor, including the 500 W and 600 W high-power modules.

Each new MDL4U Series mainframe, extension, and load module is its own dedicated product page with condition-matched pricing. Configurations using multiple modules can be assembled across mixed condition grades — for example, a new MDL4U001 mainframe with a combination of new modules — based on inventory and the customer's requirements.

Within the family, the high-voltage modules (MDL4U305 at 500 V/20 A/300 W and MDL4U505 at 500 V/30 A/500 W) address applications operating above 80 V, while the 80 V single-channel modules cover progressively higher current and power: MDL4U200 (40 A/200 W), MDL4U400 (60 A/400 W), and MDL4U600 (120 A/600 W). The dual-channel MDL4U252 and MDL4U302 are positioned for testing devices that require two independently controlled load channels in a single slot, with allocatable power between channels.

The comparison table below shows the headline electrical ratings that differentiate the seven module types: input voltage range, input current range (both low and high ranges), input power rating, and channel count. These are the specifications that determine which module fits a given device-under-test profile, since the operating mode set (CC/CV/CR/CW), the 16-bit measurement resolution, the protection feature set, and the SCPI/USBTMC interface support are common across the family.

Two additional specifications worth noting when comparing modules are minimum operating voltage at full-scale current — which varies from 1 V on the MDL4U200 and MDL4U252 up to 5.4 V on the MDL4U505 — and the CR-mode low range, which is 0.05 Ω to 10 Ω on most modules but 0.25 Ω to 10 Ω on the MDL4U305 and 0.2 Ω to 10 Ω on the MDL4U400, MDL4U505, and MDL4U600. These differences affect low-voltage source testing (such as fuel cell and solar cell applications) and low-resistance load simulation, respectively.

Additional differences in specifications beyond the few shown above are not listed here — see each model's full specifications below.

Accessories Supplied

• Power cord
• Mainframe extension cable
• Rack-mount brackets with handles

Product Core & Specifications

Please review the Manufacturer's Data Sheet to verify published specifications. Feedback on this webpage is always welcome — please reach out to your Test Architect at any time for questions or concerns. Thank you, we truly appreciate you being our customer.