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ARx Series

Magna-Power's patented Active Resistance Technology (US Patent 9,429,629) is a completely new approach to electronic loads. By utilizing a switched binary matrix of resistances and MOSFET network, combined with Magna-Power's new MagnaLINK™ distributed DSP architecture, the ARx Series delivers the same features and performance as traditional electronic loads, at a fraction of the price. In addition to the 16-bit precision voltage, current, resistance, and power control modes, the ARx Series also provides a rheostat control mode, allowing direct control of the product's internal resistance network.

Finally, an electronic load control mode with no bandwidth constraint for true step load response.

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MagnaLINK™ Distributed Digital Control

Magna-Power’s MagnaLINK™ technology provides distributed Texas Instrument DSP control across power processing stages inside the MagnaLOAD DC electronic load. This technology follows a significant internal development cycle from Magna-Power to provide a unified digital control platform across its electronic loads and power supplies, featuring fully digital control loops, adjustable control gains, programmable slew rates, digital master-slaving, and many new advanced control technologies.

All ARx Series MagnaLOADs come with the following interfaces:

  • Front panel knob, keypad, and menu system
  • 25-pin configurable external user I/O, including a high-speed analog input
  • Front and rear USB and rear RS-485 or optional Ethernet and IEEE-4888 GPIB

When in standby or diagnostic fault, the DC input bus is disconnected via a switching device.

Finally, with a dedicated +5V interlock input pin and included +5V reference on all models, external emergency stop systems can be easily integrated using an external contact.

ARx Series Digital Control Image

Six Flexible Operating Modes

To accommodate a variety of DC sources, all ARx Series MagnaLOADs come with many configurable control modes, including:

  • Voltage Mode
  • Current Mode
  • Power Mode
  • Resistance Mode
  • Shunt Regulator Mode
  • Rheostat

Preference for DC regulation is given to the parameter in the selected mode within the programmed set-points. Using the MagnaLOAD's set-points and trip settings, the product can configured to either trip with a fault when a limit is exceeded or to cross-over into a different regulation state.

Shunt Regulator Mode turns the MagnaLOAD into a high-speed smart braking resistor, engaging the DC input only when a specified voltage and exceeded by a user-defined percentage, while limiting the shunt current to a programmed set-point.

ARx Series Operating Modes Image

Configurable External User I/O

Beyond the front panel and computer controls, all MagnaLOADs come standard with a 25-pin D-Sub connector designated as the External User I/O. This connector provides:

  • 8 Digital Outputs
  • 4 Digital Inputs
  • 4 Analog Outputs
  • 4 Analog Inputs

All the analog-digital I/O ports are configurable, allowing the user to select which parameters they want to control and monitor. This configurable I/O scheme reduces complexity, eases PLC integrationand allows control parameters from various interfaces simultaneously.

The MagnaLOAD's configurable analog inputs provide 0-10V programming from PLCs and external D/A converters.

ARx Series External User I/O Image

MagnaWEB Software Interface

Magna-Power's next generation software interface, MagnaWEB, provides intuitive and user-friendly web-browser based controls for programming and measurement read-back of the MagnaLOAD's activity. Virtually all of the MagnaLOAD's available functions can be controlled and monitored from the MagnaWEB software over any of product's installed communication interfaces.

MagnaWEB uses a server-client software model to provide access to the MagnaLOAD from nearly any device and operating system. Install and run the MagnaWEB software locally on Windows then, using a web browser, access the server connected to the MagnaLOAD from a variety of devices including other desktops, tablets or smart-phones.

ARx Series MagnaWEB Software Image

Active Resistance Technology: A New Era for Electronic Loads

The ARx Series utilizes Active Resistance Technology to deliver performance consistent with conventional electronic loads, but at a fraction of the price and with the ability to directly switch passive resistors on-the-fly.

In Magna-Power's Active Resistive Technology, switched resistors are placed in series with MOSFETs. High-performance DSPs simulatenously control both dissipation elements in harmony. Assuming the power across the shunt resistor is insignificant, the power dissipated in load resistor R1 is IL x VR1 and the power dissipated in MOSFET Q1 is IL x VQ1. The resistors can be operated at higher temperatures than the MOSFETs, simplifying cooling requirements of the passive elements. Keeping VQ1 small and VR1 large lowers system costs in comparison with purely semiconductor electronic loads. Adjusting the value of resistor R1 is accomplished with a binary switching matrix. Finally, keeping the resistor switching increments small and over a wide range maintains the smallest voltages across the linear modules and over the widest operating range.

The advantage of resistive loads are reliability and cost per watt for dissipating power, while the advantage of MOSFET loads is speed of performance and the ability to dissipate power over a wide operating range. Active Resistive Technology blends switched resistance with MOSFETs to significantly lower the product's cost, add new control modes, while still delivering 16-bit precision and high-accuracy performance

ARx Series Active Resistance Image

Front Panel - Standard

Front Panel - Standard

Front Panel - Blank Panel (+BP) Option

Front Panel - Blank Panel (+BP) Option
START: Enables the DC input bus
STOP: Disables the DC input bus
Voltage measurement display
Current measurement display
4-line character display featuring a menu system, operating status and modes, product messages with diagnostic codes, resistance measurement display, and power measurement display
Control power switch, energizes the control circuits without engaging DC bus
LED indicator that the DC input is enabled
Full control (host) front panel USB port
Clean air intake, with integrated fans
Aluminum digital encoder knob for programming set-points
LED indicator of the MagnaLOAD's present regulation state, which can include: constant voltage (CV), constant current (CC), constant power (CP), or constant resistance (CR)
Selector buttons to choose which set-point the digital encoder knob and digital keypad buttons will modify
MENU: Enters the menu system on the 4-line display
BACK: Moves back one level in the menu
ENTER: Selects the highlighted menu item
CLEAR: Removes the product from a faulted state
LOCK: Locks the front panel, with password protection available

Model Ordering Guide

Model Ordering Guide

There are 4 different models in the ARx Series spanning power levels: 6.75 kW.

Use the following ordering guide and models chart to define the best model for your application.

ARx Series Ordering Guide

ARx Series Models

There are 4 different models in the ARx Series spanning power levels: 6.75 kW. To determine the appropriate model:

  1. Select the desired Max Voltage (Vdc) from the left-most column.
  2. Select the desired Max Current (Adc) from the same row that contains your desired Max Voltage.
  3. Construct your model number according to the model ordering guide.
Model Maximum Power Maximum Voltage Maximum Current Package Type Minimum Voltage
ARx6.75-100-140/UI 6.75 kW 100 Vdc 140 Adc Rack-mount 2.0 Vdc
ARx6.75-200-70/UI 6.75 kW 200 Vdc 70 Adc Rack-mount 2.5 Vdc
ARx6.75-500-28/UI 6.75 kW 500 Vdc 28 Adc Rack-mount 3.0 Vdc
ARx6.75-1000-14/UI 6.75 kW 1000 Vdc 14 Adc Rack-mount 5.0 Vdc


The following specifications are subject to change without notice. Unless otherwise noted, all specifications measured at the product's maximum ratings.

AC Input Specifications
Specification Value
AC Input Voltage
1Φ, 2-wire + ground
85 to 265 Vac (UI: Universal Input); Available on 6.75 kW Models
AC Input Frequency 50-60 Hz
AC Input Isolation ±1500 Vac, maximum input voltage to ground
Programming Interface Specifications
Specification Value
Front Panel Programming Aluminum rotary knob with encoder, keypad, or up-down arrow for single bit control
Computer Interfaces
USB Host (Front): Type B
USB Host (Rear): Type B
RS485 (Rear): RJ-45
MagnaLINK™: RJ-25 x 2
Computer Interfaces
LXI TCP/IP Ethernet (Rear): RJ-45
GPIB (Rear): IEEE-488
External User I/O Port
Analog and Digital Programming
25-pin D-sub DB-25, female
Referenced to Earth ground; isolated from the DC input
See User Manual for pin layout
Programming Specifications
Specification Value
All Modes
16-bit, 0.0015%
Programming and Measurement
Voltage: ±0.1% of full scale voltage rating
Current: ±0.2% of full scale current rating
Power: ±0.3% of full scale power rating
Resistance: ±0.3% of full scale resistance rating
Rise/Fall Time
Voltage Mode: 100 ms, 10% to 90% full scale voltage rating
Current Mode: 2 ms, 10% to 90% full scale current rating
Power Mode: 100 ms, 10% to 90% full scale power rating
Resistance Mode: 40 ms, 10% to 90% full scale resistance rating
Trip Settings Range Over Voltage: 10% to 110% of full scale voltage rating
Under Voltage: 0% to 110% of full scale voltage rating
Over Current: 10% to 110% of full scale current rating
Over Power: 10% to 110% of full scale power rating
External User I/O Specifications
Specification Value
Digital I/O Digital Input Voltage: 5V
Digital Input Impedance: 10 kΩ
Digital Monitoring Voltage: 5V, 32 mA capacity
Digital Reference Voltage: 5V, 20 mA capacity
Analog I/O Analog Sampling Rate: 2 kHz
Analog Programming Voltage: 0-10 V
Analog Programming Resolution: 12-bit, 0.025%
Analog Monitoring Voltage: 0-10 V, 3 mA capacity
Analog Monitoring Impedance: 0.005 Ω
Analog Monitoring Accuracy: 0.05% of full scale
Analog Reference Voltage: 10 V, 20 mA capacity
Physical Specifications
Specification Value
Racking Standard
6.75 kW Models Only
Rear Support Rails
6.75 kW Models
Size and Weight
6.75 kW Models
10” H x 19” W x 24” D (26.67 x 48.26 x 60.96 cm)
125 lbs (56.7 kg)
Environmental Specifications
Specification Value
Ambient Operating Temperature 0°C to 50°C
Storage Temperature -25°C to +85°C
Humidity Relative humidity up to 95% non-condensing
Air Flow Front air inlet, rear exhaust
Regulatory Compliance
Specification Value
EMC Complies with European EMC Directive for test and measurement products
Safety Complies with EN61010-1
CE Mark Yes
RoHS Compliant Yes

Options and Accessories

The following are options and accessories developed specifically for Magna-Power's ARx Series


External accessories and integration services are available for Magna-Power products


The following downloads are for the ARx Series:


ARx Series Datasheet [1.2.1] [EN] [PDF]
ARx Series Datasheet [1.2.1] [ZH] [PDF]