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MagnaLOAD ARx Series High Power Programmable Electronic DC Loads

MagnaLOAD ARx Series High Power Programmable Electronic DC Loads

Magna Power ARx Series Programmable Electronic DC Loads
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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Product Details

MagnaLINK™ Distributed Digital Control

MagnaLINK Digital Control Image

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.

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
MagnaLOAD Control Modes

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.

MagnaLOAD Control Modes

Digital Master-Slaving: Expandibility Without Compromise

All MagnaLOADs come standard with a MagnaLINK™ Input and a MagnaLINK™ Output port, which provides plug and play digital master-slaving. Simply connect the master's MagnaLINK™ Output to the slave's MagnaLINK™ Input and, using the MagnaWEB software, the products will automatically configure themselves for master-slave operation as a higher-power unit based on the populated ports. Buffered digital MagnaLINK™ connections means many MagnaLOADs can be daisy-chained in master-slave operation. Master-slave MagnaLOAD units will aggregate measurements to one display panel.

The internal MagnaLINK™ protocol was developed with expandability at the forefront. When configured for master-slave operation, the master controller takes control of all the slave's digital "targets." With this digital master-slaving strategy, it is completely transparent whether the unit is operating as a stand-alone product or in master-slave.

Configurable External User I/O

MagnaLOAD 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.

MagnaWEB Software Interface

MagnaWEB Software

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.

Extensive Programming Support

All ARx Series MagnaLOAD DC electronic loads come with a dedicated National Instruments LabVIEW™ driver, Interchangeable Virtual Instrument (IVI) driver, and support for a wide range of Standard Commands for Programmable Instrumentation (SCPI). These programming interfaces support full control, measurement, and monitoring of the MagnaLOAD. All of the MagnaLOAD's available communication interfaces are supported by these drivers and command sets, including: USB, RS-485, LXI TCP/IP Ethernet, and IEEE-488 GPIB.

Showcased in the following basic code examples, SCPI commands provide the simplest form of communication by using plain ASCII text and parameters sent over a basic socket connection. Over 40 commands are provided, with detailed documentation in the ARx Series User Manual.

Finally, Magna-Power's MagnaWEB software is provided allowing for web browser based control.

import visa
rm = visa.ResourceManager()
magna_power = rm.open_resource(USB::0x0403::0x6015::1201-2358::INSTR)
magna_power.write('VOLT 1000')
magna_power.write('CURR 20')
magna_power = visa('ni','USB::0x0403::0x6015::1201-2358::INSTR');
idn = fscanf(magna_power)
fprintf(magna-power,'VOLT 1000')
fprintf(magna-power,'CURR 20')
string resourceString = "USB::0x0403::0x6015::1201-2358::INSTR";
mbSession = (MessageBasedSession)ResourceManager.GetLocalManager().Open(resourceString);string idn;
mbSession.Timeout = 3000;
idn = mbSession.Query("*IDN?");
mbSession.Write("VOLT 1000");
mbSession.Write("CURR 20");

Active Resistance Technology Diagram

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

Front Panel - Standard

MagnaLOAD Standard Front Panel

Front Panel - Blank Panel (+BP) Option

MagnaLOAD Blank Front Panel
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
Aluminium 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
USA Flag

Designed and Manufactured in the USA, Available Worldwide

For complete control of quality, MagnaDC programmable DC power supplies are designed and manufactured at Magna-Power's vertically integrated USA manufacturing facility in Flemington, New Jersey. Heat-sinks and chassis are machined from aluminum. All sheet metal is fabricated and powder coated in-house. Magnetics are wound-to-order from validated designs based on a model's voltage and current. An automated surface-mount production line places components on printed circuit boards for control, driver, auxiliary power, and display circuits. And finally after assembly, products undergo comprehensive test and calibration, followed by an extended burn-in period

There are 24 different models in the ARx Series spanning power levels: 6.75 kW, 13.5 kW, 20.25 kW, 27 kW, 33.75 kW, 40.5 kW.

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

ARx Series Ordering Guide
ModelMaximum PowerMaximum VoltageMaximum CurrentPackage TypeMinimum Voltage
ARx6.75-100-1406.75 kW100 Vdc140 AdcRack-mount2.0 Vdc
ARx6.75-200-706.75 kW200 Vdc70 AdcRack-mount2.5 Vdc
ARx6.75-500-286.75 kW500 Vdc28 AdcRack-mount3.0 Vdc
ARx6.75-1000-146.75 kW1000 Vdc14 AdcRack-mount5.0 Vdc
ARx13.5-100-28013.5 kW100 Vdc280 AdcFloor-standing2.0 Vdc
ARx13.5-200-14013.5 kW200 Vdc140 AdcFloor-standing2.5 Vdc
ARx13.5-500-5613.5 kW500 Vdc56 AdcFloor-standing3.0 Vdc
ARx13.5-1000-2813.5 kW1000 Vdc28 AdcFloor-standing5.0 Vdc
ARx20.25-100-42020.25 kW200 Vdc420 AdcFloor-standing2.0 Vdc
ARx20.25-200-21020.25 kW200 Vdc210 AdcFloor-standing2.5 Vdc
ARx20.25-500-8420.25 kW500 Vdc84 AdcFloor-standing3.0 Vdc
ARx20.25-1000-4220.25 kW1000 Vdc42 AdcFloor-standing5.0 Vdc
ARx27-100-56027 kW100 Vdc560 AdcFloor-standing2.0 Vdc
ARx27-200-28027 kW200 Vdc280 AdcFloor-standing2.5 Vdc
ARx27-500-11227 kW500 Vdc112 AdcFloor-standing3.0 Vdc
ARx27-1000-5627 kW1000 Vdc56 AdcFloor-standing5.0 Vdc
ARx33.75-100-70033.75 kW100 Vdc700 AdcFloor-standing2.0 Vdc
ARx33.75-200-35033.75 kW200 Vdc350 AdcFloor-standing2.5 Vdc
ARx33.75-500-14033.75 kW500 Vdc140 AdcFloor-standing3.0 Vdc
ARx33.75-1000-7033.75 kW1000 Vdc70 AdcFloor-standing5.0 Vdc
ARx40.5-100-84040.5 kW100 Vdc840 AdcFloor-standing2.0 Vdc
ARx40.5-200-42040.5 kW200 Vdc420 AdcFloor-standing2.5 Vdc
ARx40.5-500-16840.5 kW500 Vdc168 AdcFloor-standing3.0 Vdc
ARx40.5-1000-8440.5 kW1000 Vdc84 AdcFloor-standing5.0 Vdc

Operating Profile

With its combination of resistor and linear elements, the ARx Series DC electronic load provides two distinct operating profiles: High Power Range and Low Power Range.

The operating profiles figures below apply to to all ARx Series models, normalized about the model's maximum voltage, current, and power ratings.

ARx Series MagnaLOAD Operating Profile - High
ARx Series MagnaLOAD Operating Profile - Low
AC Input Specifications
AC Input Voltage
85-265 Vac
1F, 2-wire + ground
AC Input Current
1.8-0.7 Aac
AC Input Frequency
50-60 Hz
AC Input Isolation
±1500 Vac, maximum input voltage to ground
Programming Specifications
All Modes
16-bit, 0.0015%
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: 350 ms, 10% to 90% full scale voltage rating
Current Mode: 700 µs, 10% to 90% full scale current rating
Power Mode: 40 ms, 10% to 90% full scale power rating
Resistance Mode: 650 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
Connectivity Specifications
Communication Interfaces
USB Host (Front): Type B
USB Host (Rear): Type B
RS485 (Rear): RJ-45
MagnaLINK™: RJ-25 x 2
External User I/O: Standard, 25-pin D-sub Female
Communication Interfaces
LXI TCP/IP Ethernet (Rear): RJ-45
GPIB (Rear): IEEE-488
External User I/O Specifications
Digital Input Voltage
5 V
Digital Input Impedance
10 kO
Digital Monitoring Voltage
5 V, 32 mA capacity
Digital Reference Voltage
5V, 20 mA capacity
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 O
Analog Monitoring Accuracy
0.05% of full scale
Analog Reference Voltage
10 V, 20 mA capacity
Physical Specifications
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)
Size and Weight
13.5 kW Models
Floor-standing single-bay cabinet with casters
30.7" H x 24" W x 31.5" D (78.0 x 61.0 x 80.0 cm)
315 lbs (142.9 kg)
Size and Weight
20.25 kW Models
Floor-standing single-bay cabinet with casters
58.25" H x 24" W x 31.5" D (148.0 x 61.0 x 80.0 cm)
440 lbs (199.6 kg)
Size and Weight
27 kW Models
Floor-standing single-bay cabinet with casters
58¼" H x 24" W x 31.5" D (148.0 x 61.0 x 80.0 cm)
565 lbs (256.3 kg)
Size and Weight
33.75 kW Models
Floor-standing single-bay cabinet with casters
74" H x 24" W x 31.5" D (188.0 x 61.0 x 80.0 cm)
690 lbs (313.0 kg)
Size and Weight
40.5 kW Models
Floor-standing single-bay cabinet with casters
74" H x 24" W x 31.5" D (188.0 x 61.0 x 80.0 cm)
815 lbs (369.7 kg)
Environmental Specifications
Ambient Operating Temperature
0°C to 50°C
Storage Temperature
-25°C to +85°C
Relative humidity up to 95% non-condensing
Air Flow
Front air inlet, rear exhaust
Regulatory Compliance
Complies with European EMC Directive for test and measurement products
Complies with EN61010-1
CE Mark
RoHS Compliant
Front Panel
6.75 kW Models
ARx Series Front Panel Diagram
Rear Panel
6.75 kW Models
ARx Series Rear Panel Diagram
Side Panel
6.75 kW Models
ARx Series Side Panel Diagram
Front Panel
13.5 kW to 40.5 kW Models
ARx Series Front Panel Diagram
Rear Panel
13.5 kW to 40.5 kW Models
ARx Series Rear Panel Diagram
DC Input Bus
13.5 kW to 40.5 kW Models
ARx Series DC Input Bus Diagram


This option provides an integrated IEEE-488 GPIB communications port, allowing the product to be fully controlled and monitored using supported commands, as well as adding some additional interface specific commands.

LXI TCP/IP Ethernet

This option provides an integrated TCP/IP Ethernet communications port, allowing the product to be fully controlled and monitored using supported commands, as well as adding some additional interface specific commands.

Accessories Available

MagnaLINK-6178886-ft MagnaLINK CableN/A
MagnaLINK-121788812-ft MagnaLINK CableN/A
MID-M17888MagnaLINK Interface Device - MasterN/A
MID-S17888MagnaLINK Interface Device - SlaveN/A
CAB1: Cabinet and Integration 11788312U Cabinet (32” H x 24” W x 31.5” D) with casters, fans, and product integrationN/A
CAB2: Cabinet and Integration 21788324U Cabinet (51.5” H x 24” W x 31.5” D) with casters, fans, and product integrationN/A
CAB3: Cabinet and Integration 31788330U Cabinet (67” H x 24” W x 31.5” D) with casters, fans, and product integrationN/A
CAB4: Cabinet and Integration 41788336U Cabinet (75” H x 24” W x 31.5” D) with casters, fans, and product integrationN/A
CAB3x2: Cabinet and Integration 3x21788360U Double Cabinet (67” H x 48” W x 31.5” D) with casters, fans, and product integrationN/A
CAB4x2: Cabinet and Integration 4x21788372U Double Cabinet (75” H x 48” W x 31.5” D) with casters, fans, and product integrationN/A

White Papers

Electronic Loads — A New Generation

A technical paper on the various electronic load technologies and a technical overview of Magna-Power Electronics patented (US Patent 9,429,629) Active Resistance Technology.

Application Notes

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