RMX-4127 1500 W 650 V Programmable DC Power Supply
The RMX-4127 is a 1500 W, single-channel programmable DC power supply designed for automated validation, production testing, component characterization and high-voltage laboratory applications. It provides a rated output range of 0 V to 650 VDC and 0 A to 7 A in a full-width 1U rack-mount enclosure.
The power supply can operate across a flexible voltage and current range within its 1500 W power envelope. Engineers can configure the RMX-4127 from its front-panel controls or remotely through LAN, USB, RS232C and analog programming interfaces.
Constant-voltage and constant-current operating modes, remote sensing, programmable protection, preset storage and master-slave parallel operation make the RMX-4127 suitable for both interactive laboratory work and fully automated high-power test systems.
Key Features of the RMX-4127
- 1500 W maximum rated output power
- Single programmable DC output channel
- 0 V to 650 VDC rated output voltage
- 0 A to 7 A rated output current
- 0 V to 682.5 V programmable voltage setting range
- 0 A to 7.35 A programmable current setting range
- Constant-voltage and constant-current operation
- Full-width 1U rack-mount enclosure
- LAN, USB 2.0 and RS232C remote interfaces
- VXI-11, HiSLIP and SCPI-RAW LAN communication
- SCPI-compatible command language
- Analog voltage and current programming
- Remote voltage and current monitoring outputs
- Remote sensing with up to 5 V compensation per line
- Overvoltage and overcurrent protection
- Overtemperature and fan-failure protection
- Low AC input and incorrect sensing protection
- Communication watchdog function
- Three front-panel preset memories
- Master-slave parallel operation with as many as four identical units
- Universal 85 VAC to 265 VAC input range
RMX-4127 Technical Specifications
| Product Model | RMX-4127 |
|---|---|
| Part Number | 784768-01 |
| Product Type | Programmable rack-mount DC power supply |
| Number of Output Channels | 1 |
| Rated Output Power | 1500 W |
| Rated Output Voltage | 0 V to 650 VDC |
| Rated Output Current | 0 A to 7 A |
| Voltage Setting Range | 0 V to 682.5 V |
| Current Setting Range | 0 A to 7.35 A |
| Voltage Setting Accuracy | ±(0.05% of setting + 0.05% of rating) |
| Current Setting Accuracy | ±(0.5% of setting + 0.1% of rating), from 0.2% to 100% of rated current |
| Voltage Line Regulation | ±67 mV |
| Voltage Load Regulation | ±67 mV |
| Current Line Regulation | ±2.7 mA |
| Current Load Regulation | ±6.4 mA |
| Voltage Ripple and Noise | 330 mV peak-to-peak or 60 mV rms |
| Current Ripple and Noise | 30 mA rms |
| Voltage Transient Response | 7 ms or less |
| Voltage Rise Time | 100 ms |
| Voltage Fall Time | 250 ms at rated load; 3000 ms at no load with bleeder enabled |
| Remote Sense Compensation | Up to 5 V per line |
| Remote Interfaces | LAN, USB 2.0 and RS232C |
| Analog Control | 0 V to 5 V or 0 V to 10 V selectable |
| Command Language | SCPI 1999.0 compatible |
| Software Protocol | IEEE 488.2-1992 |
| Nominal AC Input | 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 Input Power | 2200 VA |
| Minimum Efficiency | 74% at rated load |
| Form Factor | Full-width 1U rack mount |
| Weight | Approximately 9.0 kg |
| Cooling | Forced-air fan cooling |
| Operating Temperature | 0°C to 50°C |
| Operating Humidity | 20% to 85% RH, noncondensing |
| Maximum Operating Altitude | 2,000 m |
The RMX-4127 cannot deliver 650 V and 7 A simultaneously because that combination would exceed its 1500 W output rating. Available voltage and current combinations are limited by the constant-power output envelope.
RMX-4127 Part Number and Included Items
| Item | Part Number | Description |
|---|---|---|
| RMX-4127 | 784768-01 | 1500 W, 650 V, 7 A single-channel programmable DC power supply |
| Safety and Regulatory Documentation | Included | Product safety, environmental and regulatory information |
| AC Power Cord | Region and installation dependent | Must meet the instrument’s AC input voltage and current requirements |
| Rack-Mount Hardware | Configuration dependent | Hardware for installing the full-width 1U supply in a suitable rack |
NI states that an AC power cord is not included with the RMX-4124, RMX-4125, RMX-4126 or RMX-4127. Select a power cord, branch circuit and connector rated for the local mains voltage and maximum input current.
1500 W Constant-Power Output
The RMX-4127 can produce as much as 1500 W across a broad selection of voltage and current combinations. Its flexible power architecture allows the supply to support different high-voltage loads without requiring a separate fixed-range power source for every test.
At the full 650 V rated voltage, the maximum current allowed by the 1500 W limit is approximately 2.31 A. The 7 A rated current is available only at output voltages of approximately 214 V or lower.
Test software should monitor voltage, current and calculated power so that programmed values remain inside the permitted output envelope.
0 V to 650 VDC Output Range
The RMX-4127 is the high-voltage model in the 1500 W RMX-4124 through RMX-4127 family. Its rated output range extends from 0 V to 650 VDC, with a programmable setting range up to 682.5 V.
This voltage capability makes the supply suitable for high-voltage component evaluation, insulation-related testing, industrial power electronics, DC bus simulation and other applications that exceed the range of conventional laboratory supplies.
The output can be hazardous and potentially lethal. Use insulated enclosures, interlocks, grounding, emergency disconnects and discharge procedures appropriate for the maximum voltage and stored energy in the system.
0 A to 7 A Current Range
The rated current range is 0 A to 7 A, while the programmable setting range extends to 7.35 A. Current output remains subject to the 1500 W power limit.
The current setting acts as the regulation value in constant-current mode and as the current limit during constant-voltage operation. This helps protect the connected load from drawing more current than intended.
Constant-Voltage Operation
In constant-voltage mode, the RMX-4127 regulates the output to the programmed voltage while the load current remains below the configured current limit.
This mode is appropriate for powering equipment that requires a stable DC bus. The front-panel CV indicator shows when the supply is operating in constant-voltage regulation.
Constant-Current Operation
If the connected load attempts to draw more than the configured current setting, the RMX-4127 transitions into constant-current operation and reduces the output voltage as necessary to regulate current.
The CC indicator identifies constant-current operation. An unexpected transition from CV to CC can indicate excessive load current, a short circuit, an incorrect current setting or a device-under-test fault.
Remote Sensing
Remote sensing allows the RMX-4127 to regulate voltage at the load rather than only at its rear output terminals. The feature can compensate for as much as 5 V of voltage drop on each output line.
Remote sensing is particularly useful when the power supply and DUT are separated by long cables or when load current produces a measurable voltage drop in the wiring.
Incorrect or disconnected sense wiring can create unsafe output behavior. Route the sense leads carefully, observe polarity and follow the official connection procedure.
LAN Remote Control
The RMX-4127 includes a 10BASE-T and 100BASE-TX IPv4 LAN interface. It supports VXI-11, HiSLIP and SCPI-RAW communication protocols for integration into automated test systems.
The LAN interface uses an RJ45 connector and Category 5 straight-through cable. Network settings should be configured according to the test system’s IP addressing and security requirements.
USB 2.0 Control
The USB interface complies with USB 2.0 high-speed operation and supports the USBTMC-USB488 device class. A rear-panel USB Type-B socket provides direct connection to a control computer.
USB is convenient for benchtop automation and systems where the supply is located close to the host computer. The interface supports a nominal signaling rate of 480 Mbps.
RS232C Control
The RS232C interface supports selectable baud rates from 1200 bps to 115200 bps. It uses an RJ45 connector and requires the correct straight-through cable and host-side adapter.
Because both the LAN and RS232C connections use modular connectors, carefully verify the rear-panel label before connecting a cable. The electrical interfaces are not interchangeable.
SCPI Programming
The RMX-4127 uses a command language compliant with the SCPI 1999.0 specification and an IEEE 488.2 software protocol. Test applications can program voltage, current, protection limits, output state and instrument queries.
SCPI control makes the supply suitable for LabVIEW, TestStand, Python, C, C# and other programming environments that can communicate through LAN, USB or serial interfaces.
Analog Programming and Monitoring
The rear-panel J1 connector supports analog programming of output voltage and current. The control range can be selected as 0 V to 5 V or 0 V to 10 V, corresponding to 0% through 100% of the rated output.
The same interface provides voltage-monitor and current-monitor signals with selectable 0 V to 5 V or 0 V to 10 V output ranges.
Analog control is useful for hardware-in-the-loop systems, process-control applications and fast external control architectures that do not rely entirely on software commands.
Status and Interlock Signals
The rear-panel J2 connector provides status outputs for output-on, constant-voltage, constant-current, alarm and instrument-power conditions.
External control signals can turn the output on or off, shut down the supply and clear alarm conditions. These functions can be integrated with fixture interlocks, emergency-stop circuits and automated safety systems.
External interlocks should be validated independently and should not rely solely on software for personnel protection.
Programmable Protection Functions
The RMX-4127 includes multiple protection functions that can disable the output and report an alarm when unsafe or abnormal conditions occur.
- Adjustable overvoltage protection
- Secondary fixed overvoltage protection
- Adjustable overcurrent protection
- Undervoltage setting limit
- Overtemperature protection
- Secondary overtemperature protection
- Fan-failure protection
- Incorrect remote-sense connection protection
- Low AC input protection
- External shutdown control
- Output power limiting
- Communication watchdog protection
Overvoltage Protection
The adjustable overvoltage-protection range for the RMX-4127 is 65 V to 728 V. When the output exceeds the configured protection threshold, the supply turns off its output, displays an OVP message and activates the alarm indicator.
A second fixed protection threshold operates at 780 V, equal to 120% of the 650 V rated output voltage.
Overcurrent Protection
The programmable overcurrent-protection range is 0.7 A to 7.84 A. Activation turns off the output and reports an OCP alarm.
Overcurrent protection is different from constant-current regulation. Constant-current mode regulates the output at the programmed current, while OCP shuts the output off after the protection condition is detected.
Communication Watchdog
The communication watchdog can turn off the output if expected communication between the controlling system and the power supply is lost.
This function is useful in unattended automated tests where continued output after a control-computer or network failure could damage the DUT or create an unsafe condition.
Preset Memory
The RMX-4127 can store as many as three preset configurations. Each preset can include voltage, current, overvoltage protection, overcurrent protection and undervoltage-limit settings.
Preset storage helps operators change between frequently used test conditions without manually re-entering every parameter.
Master-Slave Parallel Operation
As many as four identical RMX-4127 units can be configured for master-slave parallel operation. This architecture increases the available current and total output power while coordinating control through a master unit.
All connected units must be the same model, and system cabling must be designed for the combined voltage, current and energy. Current sharing, output wiring, grounding and protection must follow the official parallel-operation instructions.
Series Operation Restriction
The RMX-4127 does not support series operation. Connecting RMX-4127 outputs in series can exceed the instrument’s isolation rating and create a dangerous electrical condition.
If the application requires more than 650 V, use a power supply specifically rated for the required voltage rather than connecting multiple RMX-4127 units in series.
High-Voltage Grounding Requirements
The RMX-4127 supports positive or negative output grounding within its specified limits. However, NI requires the output to remain ungrounded when generating more than 600 V.
The maximum isolation voltage is ±600 V. Grounding, fixture construction and measurement connections must be reviewed carefully before operating near the maximum output voltage.
Universal AC Input
The power supply accepts an AC input range of 85 VAC to 265 VAC at 47 Hz to 63 Hz. Its nominal rating is 100 VAC to 240 VAC, single phase.
Maximum input current is 21 A at 100 VAC and 10.5 A at 200 VAC under rated-load conditions. The maximum input power rating is 2200 VA.
The installation must provide an AC branch circuit, connector, power cord and protective earth connection rated for the actual input voltage and current.
RMX-4127 Applications
- High-voltage component testing
- Power-electronics validation
- DC bus simulation
- Automotive and electric-vehicle component testing
- Industrial inverter and converter testing
- Capacitor charging applications
- Semiconductor characterization
- Insulation and dielectric system development
- Production functional testing
- Burn-in and reliability testing
- Battery-system and energy-storage research
- Laboratory research and development
- Automated test equipment
High-Voltage Component Testing
The 650 V output range supports testing of components used in industrial and power-electronic systems. Engineers can characterize device behavior at different voltage levels while monitoring output current and power.
Suitable fixtures, current limiting, shielding and discharge paths must be included whenever exposed conductors or energy-storage components are present.
Power-Electronics Validation
The RMX-4127 can provide a programmable high-voltage DC source for converters, inverters, motor drives and related power-electronics assemblies.
Automated software can sweep the DC input voltage, apply current limits, record DUT measurements and shut down the output when a test limit is exceeded.
Electric-Vehicle Component Testing
The voltage range can support development and validation of components used in high-voltage electric-vehicle systems, provided the required current and power remain within the RMX-4127 ratings.
The supply is not a battery simulator with bidirectional power capability. Applications requiring current sinking, regenerative operation or dynamic battery modeling need additional equipment.
Burn-In and Reliability Testing
Remote programming and status monitoring allow the RMX-4127 to operate in long-duration burn-in and reliability tests. Voltage, current and protection limits can be controlled from an automated test sequence.
The test fixture should include independent safety monitoring and a controlled method for discharging the DUT after the output is turned off.
RMX-4127 Troubleshooting
The Output Does Not Turn On
Check for an active protection message, external shutdown input, communication watchdog condition or incorrect remote-control state. Confirm that the output terminals and sense leads are connected correctly.
The Supply Enters Constant-Current Mode
The connected load is requesting more current than the programmed current setting. Check the DUT resistance, current limit, output wiring and possible short circuits.
The Output Is Lower Than the Programmed Voltage
Confirm that the requested voltage and load current do not exceed the 1500 W output envelope. Also check for cable voltage drop and verify remote-sense polarity and connections.
An OVP Alarm Is Displayed
The output exceeded the programmed overvoltage-protection limit. Disconnect or disable the output, inspect the OVP setting and verify that no external source is applying voltage to the supply terminals.
An OCP Alarm Is Displayed
The current exceeded the overcurrent-protection threshold. Inspect the DUT for a short circuit and confirm that the OCP setting is appropriate for the intended load.
A SENSE Alarm Is Displayed
Check the remote-sense wiring for an open connection, reversed polarity or excessive cable voltage drop. Do not resume high-voltage operation until the sensing circuit has been verified.
A FAN or OHP Alarm Is Displayed
Stop the test and verify that the cooling air intake and exhaust are unobstructed. Check the ambient temperature, rack ventilation and operation of the internal cooling fan.
LAN Communication Does Not Work
Verify the IP address, subnet mask, cable and network connection. Confirm that the selected application is using VXI-11, HiSLIP or SCPI-RAW with the correct address and port configuration.
USB Communication Does Not Work
Check the USB Type-B cable, device driver and USBTMC recognition in the operating system. Try a direct computer connection before using an external USB hub.
The Output Remains Energized Longer Than Expected
With the bleeder circuit enabled, the specified no-load fall time can be as long as 3000 ms. External capacitors and the DUT can retain dangerous energy considerably longer, so verify the voltage with a suitable instrument before touching the circuit.
RMX-4127 Comparison with Similar Programmable Power Supplies
| Model | Rated Output | Best Suited For |
|---|---|---|
| RMX-4123 | 750 W, 650 V, 3.5 A | High-voltage applications requiring lower power |
| RMX-4124 | 1500 W, 30 V, 150 A | Very-high-current, low-voltage testing |
| RMX-4125 | 1500 W, 80 V, 56 A | Medium-voltage, high-current power testing |
| RMX-4126 | 1500 W, 230 V, 20 A | High-power testing requiring balanced voltage and current |
| RMX-4127 | 1500 W, 650 V, 7 A | High-voltage programmable DC power applications |
RMX-4127 vs RMX-4123
Both the RMX-4127 and RMX-4123 provide a maximum rated output voltage of 650 V. The RMX-4123 is rated for 750 W and 3.5 A, while the RMX-4127 doubles the capacity to 1500 W and 7 A.
Select the RMX-4123 when the application requires high voltage but remains below 750 W. Select the RMX-4127 when additional current or power is required.
RMX-4127 vs RMX-4126
The RMX-4126 and RMX-4127 are both rated for 1500 W. The RMX-4126 provides up to 230 V and 20 A, while the RMX-4127 provides up to 650 V and 7 A.
Choose the RMX-4126 when the DUT requires more current at a lower voltage. Choose the RMX-4127 when maximum voltage is the primary requirement.
RMX-4127 vs RMX-4124
The RMX-4124 provides as much as 150 A at 30 V, making it suitable for low-voltage, high-current loads. The RMX-4127 provides as much as 650 V at 7 A for high-voltage testing.
Although both supplies are rated for 1500 W, their voltage and current ranges are designed for substantially different DUT requirements.
Selecting the Right RMX-412x Power Supply
Choose the RMX-4127 when the test requires output voltage above 230 V and total power up to 1500 W. Verify that the DUT current stays within 7 A and that every operating point remains inside the constant-power envelope.
Select the RMX-4124 for low-voltage loads requiring very high current, the RMX-4125 for loads up to 80 V and 56 A, or the RMX-4126 for applications up to 230 V and 20 A.
Recommended Related Products
- RMX-4123 750 W 650 V Programmable DC Power Supply
- RMX-4124 1500 W 30 V Programmable DC Power Supply
- RMX-4125 1500 W 80 V Programmable DC Power Supply
- RMX-4126 1500 W 230 V Programmable DC Power Supply
- RMX-4120 750 W 30 V Programmable DC Power Supply
- RMX-4121 750 W 80 V Programmable DC Power Supply
- RMX-4122 750 W 230 V Programmable DC Power Supply
- View More National Instruments Products
Why Choose the RMX-4127?
- Provides output voltage up to 650 VDC
- Delivers as much as 1500 W from a compact 1U enclosure
- Supports flexible constant-voltage and constant-current operation
- Offers LAN, USB, RS232C and analog control
- Supports SCPI-based automated testing
- Compensates for cable voltage drop through remote sensing
- Includes comprehensive programmable protection functions
- Stores three frequently used configurations
- Supports parallel operation with identical units
- Accepts a wide AC input-voltage range
Frequently Asked Questions
What is the RMX-4127?
The RMX-4127 is a single-channel, 1500 W programmable rack-mount DC power supply that provides up to 650 VDC or 7 A within its constant-power operating envelope.
What is the RMX-4127 part number?
The standard NI part number for the RMX-4127 is 784768-01.
Can the RMX-4127 output 650 V at 7 A?
No. That operating point would exceed the 1500 W power rating. At 650 V, the maximum output current permitted by the power limit is approximately 2.31 A.
What remote-control interfaces are available?
The RMX-4127 supports LAN, USB 2.0, RS232C and analog remote control.
Which LAN protocols are supported?
The LAN interface supports VXI-11, HiSLIP and SCPI-RAW communication over IPv4 Ethernet.
Does the RMX-4127 support remote sensing?
Yes. Remote sensing can compensate for as much as 5 V of voltage drop on each output line.
Can multiple RMX-4127 units be connected in parallel?
Yes. Master-slave parallel operation supports as many as four identical units, including the master supply.
Can two RMX-4127 units be connected in series?
No. Series operation is not supported because it can exceed the RMX-4127 isolation-voltage rating and create a dangerous condition.
Can the RMX-4127 output be grounded?
Positive or negative grounding is possible within the specified isolation limit. The RMX-4127 must remain ungrounded when generating more than 600 V.
Does the RMX-4127 include a power cord?
No. Select an AC power cord and branch circuit appropriate for the local voltage, connector and maximum input-current requirements.
What is the maximum AC input current?
The specified maximum is 21 A at 100 VAC or 10.5 A at 200 VAC under rated-load conditions.
Is the RMX-4127 suitable for automated testing?
Yes. SCPI commands, LAN, USB, RS232C, analog control, status outputs and programmable protection functions support automated validation and production test systems.
Request a Quote for the RMX-4127
Contact us for current availability, lead time and project pricing for the RMX-4127 1500 W 650 V Programmable DC Power Supply, part number 784768-01. We can also help compare the RMX-4124, RMX-4125, RMX-4126 and RMX-4127 according to your required voltage, current and power range.
