The B&K Precision MDL4U Series is a modular programmable DC electronic load system built around a four-slot mainframe and a selection of seven interchangeable load modules. The mainframe houses a controller plus four open slots that accept any combination of modules, and the MDL4U002 mainframe extension adds four additional slots to support up to eight modules from a single connected MDL4U001 mainframe. Each load module operates independently or in coordinated fashion with the others, and dual-channel modules allow the full system to address up to sixteen channels when populated with MDL4U252 or MDL4U302 modules.

The MDL4U Series is designed for testing a broad range of DC power sources, including multi-output AC/DC power supplies, batteries, fuel cells, and photovoltaic arrays. The system supports constant current, constant voltage, constant resistance, constant power, and constant impedance operating modes, with DSP technology used to simulate non-linear loads and realistic loading behavior. Transient operation periodically switches between two load levels for evaluating supply regulation and transient characteristics, and list mode generates more complex sequences with up to 84 user-programmable steps per list.

ValueTronics International, LLC has been a specialist source for new and used electronic test and measurement equipment since 1992, and we ship every {{CONDITION}} MDL4U Series mainframe, mainframe extension, and load module from our 20,000 square foot secure warehouse at 1675 Cambridge Drive, Elgin, Illinois. Inventory is held domestically rather than drop-shipped, and our in-house team handles configuration questions, accessory matching across the seven available module types, and order fulfillment directly. Buyers working on modular load system builds reach the same engineering and operations staff that physically handles the equipment in our facility.

Brand Heritage

B&K Precision Corporation has been manufacturing test and measurement instruments for more than 60 years, with headquarters in Yorba Linda, California. The company's European presence operates through its French subsidiary Sefram in St. Etienne, and its Asian operations are based in Taipei through B+K Precision Taiwan. B&K Precision Corporation is an ISO 9001:2015 registered company, certified by NSF-ISR under certificate number 6Z241-IS8.

Compare Other Models in This Series

The MDL4U Series is a modular family built around a common four-slot mainframe (MDL4U001) and an optional four-slot mainframe extension (MDL4U002), populated with any combination of seven module types. Module power ranges from 200 W to 600 W per slot, with the dual-channel MDL4U252 and MDL4U302 modules allowing flexible power allocation between their two channels. Voltage classes split into 80 V modules and 500 V modules, and current ratings range from 20 A on the lower-current modules to 120 A on the MDL4U600.

Because every module fits a single slot regardless of power rating, system designers can mix high-power modules and dual-channel modules within the same mainframe without sacrificing slot count. All modules share the same measurement architecture, the same set of operating modes (CC, CV, CR, CW, CZ), and the same communication path through the mainframe's LAN, GPIB, USB, and RS232 interfaces.

Each new mainframe, mainframe extension, and load module listed below is its own ValueTronics product page with condition-matched pricing. Confirm the specific mainframe (MDL4U001 or MDL4U002) and the module configuration that matches your power, voltage, and channel-count requirements before placing an order.

The seven load modules differ primarily in power rating, voltage class, current rating, and channel count. The MDL4U200 (200 W, 80 V, 40 A, single channel) and MDL4U400 (400 W, 80 V, 60 A, single channel) and MDL4U600 (600 W, 80 V, 120 A, single channel) cover the 80 V single-channel power tiers. The MDL4U305 (300 W, 500 V, 20 A, single channel) and MDL4U505 (500 W, 500 V, 30 A, single channel) are the high-voltage 500 V single-channel options. The MDL4U252 (250 W max per channel, 80 V, 20 A, dual channel) and MDL4U302 (300 W per channel, 80 V, 45 A, dual channel) provide two independent channels per slot with flexible power allocation.

Mainframe selection is binary: every system starts with the MDL4U001 mainframe, and the MDL4U002 mainframe extension is added only when more than four modules are required. The mainframe contains the controller, the front-panel keypad and display, and all communication interfaces; the extension adds power capacity and four additional slots but is driven by the connected MDL4U001. Review the comparison table that follows to match module specifications against your test load requirements.

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

Accessories Supplied

• Certificate of calibration

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.