RMX-4126 1500 W 230 V 20 A Programmable DC Power Supply
The RMX-4126 is a single-channel, 1500 W programmable DC power supply designed for high-voltage power-electronics validation, converter testing, industrial equipment and automated production systems. Its autoranging architecture supports flexible voltage and current combinations with rated capabilities up to 230 VDC or 20 A.
The RMX-4126 delivers twice the output power and current capability of the RMX-4122 while retaining a compact full-width 1U rack-mount design. It supports local front-panel operation as well as automated control through LAN, USB, RS232 and external analog interfaces.
Key Features of the RMX-4126
- 1500 W maximum output power
- 230 V rated output voltage
- 20 A rated output current
- Flexible autoranging output architecture
- 0 V to 241.5 V programmable voltage range
- 0 A to 21 A programmable current range
- Single programmable DC output channel
- Constant-voltage and constant-current operation
- Four-wire remote sensing
- Up to 5 V remote-sense compensation per line
- Programmable overvoltage protection
- Programmable overcurrent protection
- Programmable undervoltage limit
- Three front-panel preset memories
- LAN, USB and RS232 communication
- External analog programming and monitoring
- Parallel operation with up to four identical units
- Series operation with up to two identical units
- Compact 1U full-width rack-mount enclosure
RMX-4126 Technical Specifications
| Product Model | RMX-4126 |
|---|---|
| Part Number | 784767-01 |
| Product Type | High-voltage programmable rack-mount DC power supply |
| Number of Output Channels | 1 |
| Rated Output Power | 1500 W |
| Rated Output Voltage | 230 VDC |
| Rated Output Current | 20 A |
| Voltage Setting Range | 0 V to 241.5 V |
| Current Setting Range | 0 A to 21 A |
| Voltage Setting Accuracy | ±(0.05% of setting + 0.05% of rated voltage) |
| Current Setting Accuracy | ±(0.5% of setting + 0.1% of rated current) |
| Voltage Line Regulation | ±25 mV |
| Voltage Load Regulation | ±25 mV |
| Current Line Regulation | ±4 mA |
| Current Load Regulation | ±9 mA |
| Voltage Transient Response | 7 ms or less under specified load-change conditions |
| Voltage Ripple and Noise | 120 mV peak-to-peak; 25 mV RMS |
| Current Ripple and Noise | 60 mA RMS under specified conditions |
| Voltage Rise Time | 100 ms |
| Voltage Fall Time | 150 ms at rated load; 1500 ms at no load with bleeder enabled |
| Remote-Sense Compensation | Up to 5 V per output line |
| Overvoltage Protection Range | 23 V to 257.6 V |
| Fixed Secondary Overvoltage Protection | 276 V |
| Overcurrent Protection Range | 2 A to 22.4 A |
| Undervoltage Limit Range | 0 V to 241.5 V |
| AC Input Rating | 100 VAC to 240 VAC, 50 Hz to 60 Hz, single phase |
| AC Input Voltage Range | 85 VAC to 265 VAC |
| AC Input Frequency Range | 47 Hz to 63 Hz |
| Maximum AC Input Current | 21 A at 100 VAC; 10.5 A at 200 VAC |
| Maximum AC Input Power | 2200 VA at 100 VAC |
| Minimum Efficiency | 74% at rated load |
| Minimum Power-Interruption Hold-Up | 20 ms |
| LAN Interface | 10Base-T or 100Base-TX Ethernet, IPv4 |
| Additional Interfaces | USB, RS232 and analog control |
| Parallel Operation | Up to four identical RMX-4126 units including the master |
| Series Operation | Up to two identical RMX-4126 units |
| Preset Memory | Three groups of output and protection settings |
| Output-to-Ground Isolation | ±500 V maximum |
| Rack Size | 1U, full rack width |
| Weight | Approximately 9 kg |
| Cooling Method | Forced-air fan cooling |
| Operating Temperature | 0°C to 50°C |
| Operating Humidity | 20% to 85% RH, noncondensing |
| Maximum Altitude | 2,000 m |
RMX-4126 Part Number and Included Items
| Item | Part Number | Description |
|---|---|---|
| RMX-4126 | 784767-01 | 1500 W, 230 V, 20 A single-channel programmable DC power supply |
| Power Supply | Included | One full-width 1U RMX-4126 power supply |
| Output Terminal Hardware | Included with instrument | M5 output connection hardware and protective terminal cover |
| Safety Documentation | Included | Safety, environmental and regulatory documentation |
| AC Input Cable | User supplied | Facility-specific cable for connection to a dedicated switchboard circuit |
The RMX-4126 does not use an ordinary removable IEC power cord. Its high-power AC input requires connection to a suitable facility circuit by qualified personnel using the specified cable, protective earth and dedicated circuit breaker.
1500 W Autoranging Output
The RMX-4126 operates across a broad combination of voltage and current settings while limiting total output power to 1500 W. Its autoranging architecture provides flexible operation for DUTs whose power requirements change with voltage.
The rated 230 V and 20 A limits cannot be delivered simultaneously because that operating point would require 4600 W. At 230 V, the maximum available current is approximately 6.52 A. At 20 A, the available voltage is approximately 75 V.
Confirm that every required voltage and current combination falls within the 1500 W operating envelope before selecting the supply.
230 V Rated Output Voltage
The RMX-4126 has a rated output voltage of 230 V and a programmable setting range extending to 241.5 V. This range supports high-voltage DC converters, industrial electronics, battery-stack simulation and power-device validation.
Because the output can exceed hazardous voltage levels, the test fixture must provide suitable insulation, covers, interlocks, grounding and operator protection.
20 A Rated Output Current
The supply provides rated current up to 20 A, with a programmable setting range extending to 21 A. This allows the RMX-4126 to deliver significant current across low-, medium- and high-voltage operating points.
Output current remains subject to the 1500 W limit. As voltage rises above approximately 75 V, the maximum available current decreases.
Constant-Voltage Operation
In constant-voltage mode, the RMX-4126 regulates the programmed voltage while allowing the DUT to draw current up to the configured current setting. The CV indicator shows when voltage regulation is active.
If the load attempts to draw more than the configured current, the supply transitions into constant-current operation and reduces the voltage as required.
Constant-Current Operation
In constant-current mode, the RMX-4126 regulates the programmed current while the output voltage changes according to the connected load. The voltage setting establishes the maximum permitted output voltage.
Constant-current operation supports component conditioning, controlled charging experiments and power-device tests requiring a regulated current stimulus.
Four-Wire Remote Sensing
The RMX-4126 supports four-wire remote sensing to compensate for voltage drop in the load cables and test fixture. Separate sense wires measure voltage directly at the DUT terminals.
The remote-sense terminals can compensate for up to 5 V of voltage drop on each output line. The output remains limited by the 241.5 V maximum setting and the 1500 W power envelope.
Remote-Sense Wiring
Use twisted-pair or two-core shielded wiring for the sense connections. Route sense wires separately from high-current conductors and switching nodes whenever possible.
Connect the positive and negative sense terminals with the correct polarity. Incorrect, loose or disconnected sensing conductors can cause unstable output or unexpected terminal voltage.
Voltage Regulation
The RMX-4126 specifies voltage line regulation and voltage load regulation of ±25 mV. These values help the supply maintain stable output when the AC input or DUT current changes.
Remote sensing should be used when cable voltage drop would otherwise reduce regulation accuracy at the device under test.
Transient Response
The RMX-4126 provides a voltage transient-response time of 7 ms or less under the specified load-change conditions. This allows the output to recover after a DUT changes its current demand.
Actual response depends on cable length, fixture impedance, remote-sense wiring, load dynamics and external capacitance.
Voltage Ripple and Noise
Voltage ripple and noise are specified at 120 mV peak-to-peak and 25 mV RMS under the applicable measurement conditions. Current ripple is specified at 60 mA RMS.
Use correct grounding, shielding and separation from low-level measurement wiring when testing noise-sensitive electronics.
Programmable Overvoltage Protection
The primary overvoltage protection threshold can be configured between 23 V and 257.6 V. If the threshold is exceeded, the RMX-4126 disables its output, displays OVP and activates the alarm indicator.
A secondary fixed overvoltage protection threshold is set at 276 V, equal to 120% of the rated voltage. Configure the primary OVP threshold below the DUT’s maximum safe voltage.
Programmable Overcurrent Protection
The OCP threshold can be configured between 2 A and 22.4 A. When an overcurrent condition activates OCP, the supply turns off the output and reports the alarm.
OCP is different from normal constant-current regulation. The current setting controls expected operation, while OCP provides a separate shutdown threshold for faults.
Undervoltage Limit
The programmable undervoltage limit prevents the output from being set below a defined voltage. Its range extends from 0 V to 241.5 V.
This function can prevent an incorrect low-voltage setting from placing the DUT in an unstable or excessive-current operating state.
Bleeder Circuit
The internal bleeder circuit helps discharge voltage from the output after the output is disabled. With the bleeder enabled, the specified voltage fall time is 150 ms at rated load and 1500 ms at no load.
If the bleeder is disabled, hazardous voltage may remain at the output terminals after output shutdown or AC power removal. Always measure the output and verify a safe voltage before touching any connection.
Three Preset Memories
The RMX-4126 can store up to three groups of voltage, current, OVP, OCP and undervoltage-limit settings. The PRESET indicators identify the active stored configuration.
Preset memory simplifies repeated manual testing and reduces configuration errors when operators switch between several DUT profiles.
Front-Panel Operation
The front panel includes voltage and current displays, control buttons and rotary controls. Engineers can configure the output, protection thresholds and communication settings without creating a software application.
Status indicators show output, constant-voltage, constant-current, alarm, power-limit, key-lock and remote-operation conditions.
LAN Remote Control
The LAN interface supports IEEE 802.3 10Base-T and 100Base-TX Ethernet over IPv4 through an RJ45 connector. It is useful for production racks and remotely controlled laboratories.
Configure the instrument’s IP address and network parameters before connecting the application. The network must permit communication between the controller and supply.
USB Connectivity
The USB interface provides a direct connection to a nearby computer for instrument configuration, development and automated testing.
Install the required communication software and driver, then verify that the RMX-4126 is recognized as an accessible VISA resource.
RS232 Serial Communication
The RS232 interface supports industrial controllers and legacy automated test systems that use serial instrument communication.
Confirm that the controller and RMX-4126 use matching COM-port, baud-rate, data-format and termination settings.
External Analog Control
The external analog interface allows voltage or resistance signals to program the output. Analog monitor signals can represent output voltage, current and operating state.
This interface supports real-time controllers, hardware-in-the-loop systems and other applications that require direct hardware control.
Parallel Operation
Up to four identical RMX-4126 units, including the master, can be configured for supported master-slave parallel operation. This increases the available current and total power while retaining the voltage range.
A four-unit installation may provide up to 6000 W within its combined operating envelope. The AC distribution, output bus, cooling and protection system must be designed for the total capacity.
Series Operation
Up to two identical RMX-4126 supplies can be connected in a supported series configuration to increase available output voltage.
The complete arrangement must remain within the ±500 V output-to-ground isolation rating. Review grounding, insulation, remote sensing and safety interlocks before operating supplies in series.
Dedicated AC Input Installation
The RMX-4126 accepts a nominal single-phase input of 100 VAC to 240 VAC. The accepted input range is 85 VAC to 265 VAC, with a maximum current of 21 A at 100 VAC or 10.5 A at 200 VAC.
Installation requires a dedicated facility breaker with a rating no greater than 30 A. The breaker must remain accessible and must not supply unrelated equipment.
AC Input Cable Requirements
NI specifies a three-core input cable with a nominal conductor area of 5.5 mm², an outside diameter between 10.5 mm and 14.4 mm, a voltage rating of at least 250 V and a maximum length of 3 m.
The line, neutral and protective-earth conductors must be connected to their matching terminals. AC wiring should only be installed by qualified personnel.
Output Wiring and High-Voltage Safety
The RMX-4126 uses bolted M5 output terminals. Select cables, ring terminals and insulation for the maximum possible voltage and current, not only the normal operating point.
Install the protective output terminal cover before energizing the instrument. De-energize the AC input and confirm that the output has discharged before changing any wiring.
Output Isolation and Grounding
The output-to-ground isolation rating is ±500 V maximum. Positive or negative output grounding is possible when the complete system remains within this limit.
Review the grounding of oscilloscopes, electronic loads and measurement instruments. A grounded instrument connection can unintentionally reference a floating RMX output to earth.
Typical RMX-4126 Applications
- High-voltage DC-DC converter testing
- Industrial power-electronics validation
- Inverter subsystem testing
- Motor-drive electronics testing
- Automotive and electric-vehicle component testing
- Battery-stack simulation
- Aerospace power-system validation
- High-voltage component conditioning
- Production functional testing
- Power-supply development
- Burn-in and reliability testing
- Research and laboratory automation
- Rack-mounted automated test equipment
High-Voltage Converter Testing
The RMX-4126 can provide programmable input power for high-voltage DC-DC converters and power-electronic assemblies. Test software can sweep the input voltage and monitor conversion efficiency, output regulation and protection behavior.
A compatible electronic load can be connected to the converter output to build a complete automated source-and-load characterization system.
Automotive and Electric-Vehicle Testing
The 230 V range supports various high-voltage automotive and electric-vehicle subsystems. The flexible power envelope can reproduce different DC operating points during development and validation.
Applications requiring bidirectional energy flow, regenerative operation or fast standardized transients may require additional specialized equipment.
Battery-Stack Simulation
The RMX-4126 can simulate the unidirectional DC output of a battery stack within its voltage, current and power limits. This supports testing converters, controllers and battery-powered electronic systems without using a physical battery for every procedure.
The RMX-4126 is not a regenerative battery emulator. Returned energy and bidirectional testing require an appropriate bidirectional source or load system.
Burn-In and Reliability Testing
The supply can continuously power electronic devices during environmental, burn-in and lifetime testing. Remote interfaces allow output and alarm conditions to be controlled by automated software.
Maintain adequate rack airflow and ensure that facility wiring, fixture insulation and output cables are suitable for continuous high-power operation.
Calibration and Warm-Up
The RMX-4126 ships with a calibration utility. The official performance specifications assume a 30-minute warm-up with current flowing and correct calibration at 23°C ±5°C.
Calibration intervals should follow NI recommendations and the organization’s usage, uncertainty and quality requirements.
RMX-4126 Troubleshooting
The RMX-4126 cannot output 230 V at 20 A
The two maximum ratings cannot be delivered simultaneously because the output is limited to 1500 W. At 230 V, the available current is approximately 6.52 A. At 20 A, the available voltage is approximately 75 V.
The RMX-4126 does not power on
Confirm the dedicated breaker, facility input, line, neutral and protective-earth connections. AC input wiring must only be inspected or modified by qualified personnel.
The output voltage is lower than programmed
Check whether the supply has entered constant-current mode or reached its 1500 W power limit. Inspect the output and remote-sense wiring.
Voltage remains after output shutdown
Verify the bleeder-circuit setting and allow sufficient discharge time. Measure the terminals and confirm a safe voltage before touching the output.
The power-limit indicator is active
The requested voltage and current combination exceeds 1500 W. Reduce the voltage, reduce the required current or use additional supplies in an approved configuration.
The remote-sense output is unstable
Check sense polarity, cable shielding and routing. Use twisted-pair sense conductors and keep them away from switching and high-current wiring.
The supply reports an OVP alarm
Verify that the OVP threshold is above the intended operating voltage. Inspect the remote-sense circuit and check whether another source is applying voltage to the output.
The supply reports an OCP alarm
Check for a short circuit, excessive inrush current or an incorrectly configured threshold. OCP shuts down the output and is separate from constant-current operation.
The LAN connection does not work
Confirm the IP address, subnet mask, Ethernet cable and network-link status. Verify that security settings permit communication with the instrument.
The unit shuts down during continuous operation
Review the alarm message, AC input, rack airflow, cooling fan and ambient temperature. Ensure that ventilation openings are not obstructed.
RMX-4126 Comparison with Similar Programmable Power Supplies
| Model | Rated Output | Power | Best Suited For |
|---|---|---|---|
| RMX-4122 | 230 V, 10 A | 750 W | Lower-power high-voltage testing |
| RMX-4124 | 30 V, 150 A | 1500 W | Low-voltage, very-high-current testing |
| RMX-4125 | 80 V, 56 A | 1500 W | Medium-voltage power electronics |
| RMX-4126 | 230 V, 20 A | 1500 W | High-voltage, high-power converter testing |
| RMX-4127 | 650 V, 7 A | 1500 W | Very-high-voltage device testing |
| PXIe-4136 | High-voltage precision SMU | Lower power | Precision source-and-measure applications |
RMX-4126 vs RMX-4122
The RMX-4122 and RMX-4126 both provide rated output voltage up to 230 V. The RMX-4126 doubles the output power from 750 W to 1500 W and doubles rated current from 10 A to 20 A.
Select the RMX-4122 when 750 W is sufficient and a standard IEC input connection is preferred. Select the RMX-4126 when the DUT requires more current or power.
RMX-4126 vs RMX-4125
The RMX-4125 provides higher current at voltages up to 80 V, while the RMX-4126 extends the voltage range to 230 V with a lower current rating.
Select the RMX-4125 for medium-voltage systems requiring substantial current. Choose the RMX-4126 when the application requires voltage above 80 V.
RMX-4126 vs RMX-4127
The RMX-4127 extends rated output voltage to 650 V but reduces rated current to 7 A. The RMX-4126 provides greater current for systems operating at 230 V or below.
Choose the RMX-4126 for high-power converters and industrial electronics. Choose the RMX-4127 for very-high-voltage DUTs requiring more than 230 V.
Recommended Related Products
- RMX-4122 750 W 230 V Programmable Power Supply
- RMX-4124 1500 W 30 V 150 A Programmable Power Supply
- RMX-4125 1500 W 80 V Programmable Power Supply
- RMX-4127 1500 W 650 V Programmable Power Supply
- RMX-4104 High-Power Programmable DC Power Supply
- PXIe-4136 High-Voltage Source Measure Unit
- View More NI PXI and PXI Express Modules
Selecting the Right RMX Power Supply
Choose the RMX-4126 when the application requires voltage up to 230 V, current up to 20 A and total output power up to 1500 W. It is especially suitable for high-voltage converters, industrial electronics and electric-vehicle component validation.
Select the RMX-4122 when 750 W is sufficient. Choose the RMX-4125 for higher current below 80 V or the RMX-4127 for voltage above 230 V.
Why Choose the RMX-4126?
- Provides 1500 W from one programmable output
- Supports voltage up to 230 VDC
- Supports current up to 20 A
- Offers flexible autoranging operation
- Provides four-wire remote sensing
- Includes programmable OVP, OCP and UVL protection
- Supports LAN, USB, RS232 and analog control
- Supports parallel and series configurations
- Provides ±500 V output-to-ground isolation
- Occupies only 1U of rack height
Frequently Asked Questions
What is the RMX-4126?
The RMX-4126 is a single-channel, 1500 W autoranging programmable DC power supply with rated output capability up to 230 V or 20 A.
Can the RMX-4126 output 230 V and 20 A simultaneously?
No. That operating point would require 4600 W. Voltage and current combinations are limited to a maximum output power of 1500 W.
What is the voltage setting range?
The programmable voltage range is 0 V to 241.5 V. The rated output voltage is 230 V.
What is the current setting range?
The programmable current range is 0 A to 21 A. The rated output current is 20 A.
Does the RMX-4126 use a standard IEC power cord?
No. The RMX-4126 requires a suitable facility input cable connected to a dedicated circuit and protective breaker by qualified personnel.
Does the RMX-4126 support remote sensing?
Yes. Its remote-sense terminals can compensate for up to 5 V of voltage drop on each output line.
Can multiple RMX-4126 units be connected in parallel?
Yes. Up to four identical RMX-4126 units, including the master, can be used in a supported parallel configuration.
Can RMX-4126 units be connected in series?
Yes. Up to two identical units can be used in a supported series configuration, subject to grounding and isolation requirements.
Which communication interfaces are available?
The RMX-4126 supports LAN, USB, RS232 and external analog control.
What is the RMX-4126 part number?
The standard NI part number for the RMX-4126 is 784767-01.
Request a Quote for the RMX-4126
Contact us for current availability, lead time and project pricing for the RMX-4126 1500 W 230 V 20 A Programmable DC Power Supply. We can also help identify compatible AC input wiring, high-voltage output cables, rack accessories and related RMX power supplies for your automated test system.
