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A Load Resistor Box is an electrical testing device that uses resistor elements to simulate actual power consumption conditions of electrical equipment. By converting electrical energy into controlled heat during operation, it allows engineers to evaluate output stability, load capacity, overload response, protection functions, and long-term operating reliability.
Unlike braking resistor solutions that are mainly designed to absorb regenerative energy from motor deceleration, a load resistor box functions as a controllable test load for verifying the performance of power sources and power conversion equipment.
The internal resistor assembly consists of multiple corrugated resistor elements arranged through series and parallel connections to achieve different load configurations. Independent load sections allow users to adjust testing conditions by switching different resistor groups without changing the overall hardware structure.
The working process can be described as:
Power Equipment Output → Load Resistor Box Input → Resistor Load Consumption → Performance Data Evaluation
The enclosure is manufactured with aluminum-zinc coated steel sheet, providing mechanical protection, efficient heat dissipation, corrosion resistance, and convenient installation. A dedicated terminal block is integrated for external electrical connection, while optional forced air cooling is available for applications requiring continuous high-power operation.
| Parameter | Specification |
|---|---|
| Power Range | 1KW-30KW |
| Working Voltage | ≤1200V |
| Resistance Range | 0.01Ω---1KΩ |
| Resistance Tolerance | ±3/±5/±10 |
| Protection Grade | IP20/IP23 |
| Temperature Coefficient | ≤300 ppm/℃ |
| Flame Retardant Grade | UL 94V-2 |
| Standard Compliance | GB-5792 |
The equipment provides controlled load conditions for verifying UPS rated output capability, overload response, voltage stability, and long-duration operating performance. By applying different load levels, engineers can evaluate UPS behavior under conditions that more closely represent actual operating requirements.
As an artificial electrical load, the equipment can be used to verify generator capacity before commissioning or during scheduled maintenance. Typical applications include diesel generator testing, backup power system inspection, and factory acceptance testing, helping confirm output performance under defined load conditions.
The controlled resistive load allows engineers to evaluate output current capability, thermal performance, protection functions, and long-term operating reliability of inverters and power supplies. Adjustable load conditions also support testing at different stages of equipment operation.
The system provides controlled discharge loads for battery systems, PCS equipment, and energy management systems, allowing engineers to assess discharge performance and operating stability under specified electrical conditions.
The internal circuits are divided into multiple independent load groups, allowing power to be adjusted progressively according to the required test profile. This configuration supports flexible load combinations, repeatable testing conditions, and easier fault isolation when individual sections require inspection.
The system can reproduce different load conditions, from light-load operation through full-load and short-term overload testing, allowing engineers to evaluate equipment performance across a broader operating range.
| Test Condition | Purpose |
|---|---|
| Light Load | Verify low-power operation |
| Half Load | Check medium-load performance |
| Full Load | Confirm rated capacity |
| Overload | Evaluate protection capability |
The integrated terminal structure can be configured for both AC and DC testing applications, providing greater flexibility when testing different types of power equipment. With a maximum working voltage of 1200V, the system can accommodate a range of industrial power testing requirements without requiring changes to the basic resistor structure.
Before installation, select the appropriate power rating, resistance value, and protection grade according to the tested equipment output power, required test conditions, and installation environment. Proper specification matching is essential for safe energy dissipation during testing.
Inspect the enclosure, terminal blocks, and cooling system before installation to confirm that the equipment is intact and ready for operation. Any visible damage or abnormality should be addressed before electrical connection.
Install the equipment in a well-ventilated location with sufficient clearance for heat dissipation. The installation area should be kept away from flammable materials, restricted airflow conditions, and excessive humidity that could affect safe operation.
Use the mounting holes provided on the enclosure to securely install the unit on the floor or designated test platform. The mounting structure should be suitable for the equipment weight and operating conditions.
Connect the output terminals of the tested equipment to the load input terminals according to the supplied wiring diagram. For DC applications, polarity must be confirmed, while all terminal connections should be properly tightened and connected with cables suitable for the expected current.
After verifying the complete electrical connection, begin testing at a low load level and gradually increase the active load sections according to the test procedure. During operation, monitor resistor temperature and other relevant operating conditions to ensure the equipment remains within the specified range.
Dufew Load Resistor Box is designed for long-duration electrical testing and undergoes electrical and mechanical performance verification before delivery. Testing focuses on resistance characteristics, electrical safety, mechanical integrity, and stable operation under different load conditions, helping ensure reliable performance in industrial testing environments.
| Electrical Characteristics | Test Conditions | Performance |
|---|---|---|
| Dielectric Strength | 2500VAC/50Hz/60S | Leakage current ≤10mA |
| Insulation Resistance | 1000VDC | Insulation resistance ≥100MΩ |
| Short-Time Overload | 10 times rated power 5S | No visible damage |
| Long-Term Load Life | Cyclic operation (Discharge 10S, Interval 90S) | More than 9000h |
| Steady-State Damp Heat | 40℃±2/90%-95%RH/100h | △R≤±（1%R+0.05Ω） |
| Rapid Temperature Change | -55℃, 55℃, 155℃ each for 15 minutes, 5 cycles | △R≤±（2%R+0.05Ω） |
| Heat Resistance | 350℃/2h | No obvious discoloration or damage |
| Temperature Coefficient | Comparison between resistance under rated load and static resistance | Less than 300 ppm/℃ |
| Flame Retardancy | 10 times rated power for 5 minutes | Red glow but no flame |
The enclosure structure is designed to withstand transportation, installation, and industrial operating environments. Mechanical tests ensure the terminal system and housing structure maintain reliability during long-term use.
| Mechanical Characteristics | Test Conditions | Performance |
|---|---|---|
| Terminal Strength | 45N/30S | No loosening or visible damage |
| Vibration Resistance | 5-200Hz、1g、98m/S² | No visible structural damage |
| Soldering Heat Resistance | Lead terminal immersed in 350±5℃ solder for 3S | △R≤±（1%R+0.05Ω） No visible external damage, clear marking |
| Solderability | Terminal immersed in 235±5℃ solder for 5S | Terminal surface solder coverage ≥95% |
Different testing requirements require different load conditions. The internal resistor groups can be configured into multiple independent sections, allowing users to adjust the applied load according to actual test procedures.
Typical configurations include:
| Load Mode | Testing Purpose |
|---|---|
| Low Load | Verify startup performance and low-power operation |
| Medium Load | Evaluate partial output capability |
| Full Load | Confirm rated power performance |
| Overload Load | Check protection response and system stability |
This sectional design allows engineers to perform multiple tests with one unit instead of preparing several fixed-value load devices.
For production testing, laboratory verification, and equipment reliability evaluation, load equipment often needs to operate under continuous and demanding conditions. Dufew Load Resistor Box is designed with stable resistance performance, optimized heat dissipation structure, independent resistor grouping, and optional forced air cooling to support long-duration high-power testing.
This design makes it suitable for applications such as factory aging tests, generator performance verification, UPS reliability evaluation, and power supply testing, where consistent load conditions are required.
Suzhou Dufew Electrical Co., Ltd. applies structured quality control procedures throughout the manufacturing process, covering material inspection, assembly control, and final performance verification. Each stage is managed to ensure electrical reliability, mechanical stability, and consistent product performance.
Incoming materials are inspected to verify the quality of resistor elements, metal enclosure materials, terminal components, and insulation materials before production.
During assembly, Dufew controls resistor grouping, electrical connection reliability, insulation distance, and mechanical fixing to ensure the finished product meets technical requirements.
Before delivery, each unit undergoes comprehensive verification, including resistance measurement, insulation testing, dielectric strength testing, structural inspection, and functional performance checks.
Suzhou Dufew Electrical Co., Ltd. specializes in power electronics components, including resistors, braking systems, reactors, transformers, and power filters. Through experience in industrial automation, energy systems, and electrical equipment applications, Dufew understands the practical requirements of reliable testing environments.
Different testing projects require different electrical and mechanical configurations. Dufew provides customized solutions according to rated power, resistance value, voltage level, load steps, cooling requirements, enclosure structure, and installation conditions, helping customers achieve suitable testing performance for specific equipment.
Dufew supports equipment manufacturers, system integrators, electrical distributors, and industrial users with engineering assistance, customized manufacturing, and standardized production processes. These capabilities help ensure stable supply and reliable electrical solutions for global industrial applications.
A load testing system requires not only sufficient power capacity but also accurate load simulation, stable long-term operation, and convenient operation. Compared with fixed single resistors or conventional braking resistor solutions, Dufew Load Resistor Box provides more flexible testing functions for power equipment verification.
| Comparison Dimension | Load Resistor Box | Traditional Single Resistor / Braking Resistor Box |
|---|---|---|
| Main Application Purpose | Designed for power equipment testing, aging tests, and performance verification of UPS, generators, inverters, and power supplies. | Mainly designed for energy consumption during motor braking or fixed resistance applications. |
| Load Adjustment Capability | Multiple independent resistor sections allow step-by-step load switching to simulate different operating conditions. | Usually provides fixed resistance values with limited or no adjustable load capability. |
| Testing Flexibility | Supports light load, half load, full load, and overload simulation for comprehensive equipment evaluation. | Mainly used for a single operating condition and cannot effectively simulate various test scenarios. |
| AC/DC Compatibility | Designed with unified terminal connection, allowing both AC and DC power equipment testing according to configuration requirements. | Many solutions are designed for specific DC bus or braking applications and have limited versatility. |
| Continuous Load Operation | Optimized enclosure structure and thermal design support long-duration load testing and aging operation. | Many braking resistor products focus on short-time energy absorption and may experience higher temperature rise during continuous loading. |
| Maintenance Convenience | Independent load circuits simplify inspection and troubleshooting. Individual sections can be checked separately during maintenance. | Fixed internal structures make troubleshooting and replacement more complicated. |
Load testing equipment is mainly used to simulate electrical loads and verify the performance of power systems, including output capacity, stability, and overload response of generators, UPS systems, inverters, and power supplies. Braking resistor solutions are mainly applied in motor drive systems to absorb regenerative energy during deceleration and prevent DC bus overvoltage.
The system uses sectional load control, where internal resistor groups are divided into independent circuits. By switching different sections, users can simulate various operating conditions, including light load, partial load, rated load, and overload conditions. This configuration improves testing flexibility and repeatability.
The cooling method is selected according to power capacity, operating duration, installation environment, and heat dissipation requirements. Standard configurations use natural airflow, while forced air cooling can be added for applications requiring higher power output or extended continuous operation.
Yes. Dufew Electric can customize resistance values, rated power, voltage levels, load steps, cooling methods, enclosure structures, and terminal configurations according to specific testing requirements.
It is suitable for performance verification, maintenance testing, aging tests, and laboratory evaluation of generators, UPS systems, inverters, DC power supplies, chargers, energy storage conversion equipment, and other industrial power systems.
Yes. Dufew Electric provides engineering support based on customer equipment specifications and testing requirements, helping design suitable configurations for different power capacities, electrical conditions, and installation environments.
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No. 364, Kangyang Road, Huangdai Town, Xiangcheng District, Suzhou City, Jiangsu Province, China
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