Open Air Current sensing Resistor

Open-Air Design & Thermal Advantage

The Open Air Current Sensing Resistor from RST Electric provides a specialized solution for engineers who need to accurately measure high currents in compact electronic assemblies. Unlike traditional surface-mount shunts that dissipate heat directly into the PCB, this Open Air Resistor uses a vertical, radial-lead configuration that positions the metal alloy sensing element above the circuit board. This unique construction creates an air gap beneath the component, allowing natural convection to carry heat away and significantly reducing thermal stress on nearby traces and components—a critical advantage in densely packed power stages.

Core Construction & Performance

The core of this Low Ohmic Resistor is a precision metal alloy element (constantan or nichrome), selected for its stable temperature coefficient (40 ppm/°C) and ability to maintain accuracy over temperature variations. The element is formed into an open-air loop and supported by robust tinned copper leads that also serve as the electrical connection. This design minimizes parasitic inductance, making the OAR series particularly suitable for high-frequency switching circuits where conventional wirewound resistors would introduce unacceptable phase shifts. The entire assembly is Pb-free and RoHS compliant, with a flameproof construction that meets stringent safety requirements.

OAR Series Specs & Manufacturing Expertise

The OAR series spans a resistance range of 5mΩ to 100mΩ—ideal for generating low-level voltage drops proportional to currents from several amperes to tens of amperes. Standard tolerances of ±1%, ±2%, and ±5% accommodate both precision instrumentation and general-purpose applications. The 1W, 3W, and 5W power ratings cover a broad spectrum of uses, from CPU core power monitoring to battery discharge detection. As a trusted Open Air Current sensing Resistor manufacturer in China, RST Electric combines over 10 years of precision resistor engineering with rigorous quality control to deliver components that provide accurate, reliable current feedback in demanding power electronics.

Technical Specification

Product Features

Our Open Air Current Sensing Resistor is specifically designed for precise current detection scenarios, fully meeting the stringent requirements of the power electronics field.

We adopt an open vertical structure design, raising the resistor element above the PCB circuit board to form a bottom air gap. This allows for rapid heat dissipation through natural convection, effectively reducing thermal stress on adjacent circuits and sensitive components. This design is particularly advantageous in densely packed power modules, significantly enhancing the overall stability.

The product's resistance value covers an ultra-low range of 5mΩ to 100mΩ, enabling large current measurement while reducing power loss and voltage drop. It is equipped with a 40ppm/°C low temperature coefficient, maintaining resistance stability in temperature-changing environments and ensuring the accuracy of current detection, suitable for dynamic working scenarios.

The product features an open-loop non-wound structure, minimizing parasitic inductance and adapting to high-frequency switching circuits, avoiding phase shifts. The core components are made of precision alloys such as copper-nickel (CuNi) and nickel-chromium (NiCr), combined with a fully welded structure, ensuring strong mechanical and electrical connections that can withstand vibration and thermal stress, with a long service life.

In addition, the product is compact in size, with a vertical layout that significantly saves PCB board space compared to horizontal axial or large SMD shunt resistors, meeting the requirements for dense layout. Radial leads can adapt to standard PCB hole diameters, compatible with wave soldering and manual assembly, balancing automation production and manual operation needs, while complying with RoHS standards, featuring a fireproof structure, meeting the safety and environmental protection requirements of industrial and consumer electronics, with tolerances as low as ±0.5%, suitable for high-precision detection scenarios.

Product Applications

Drawing and dimensions

Package and shipment

RST Electric attaches great importance to the transportation safety of each Open Air Current sensing Resistor. It has formulated a comprehensive packaging and delivery plan to ensure that the products are delivered intact to the customers and to guarantee the purchasing experience.

In terms of batch packaging, each resistor is placed in a shockproof bag with foam padding, and then placed in a corrugated cardboard box. This effectively prevents the leads from bending and the components from deforming, avoiding damage from collisions during transportation. For the lead parts, we use foam end caps or plastic lead positioning pads to fix them, ensuring that the leads remain straight and not affecting the subsequent installation and use.

For each shipment, we will attach a packing list and inspection certificate with the goods, facilitating customer acceptance and verification, and meeting compliance review requirements. The shipping method is flexibly adapted to different purchase quantities: small batch orders are sent by international express services such as DHL, FedEx, and UPS, with fast delivery; medium batch orders are selected for air transportation, balancing delivery time and cost; large batch orders are sent by sea transportation, reducing transportation costs, and fully meeting the delivery time requirements of customers.

Before packaging all products, 100% electrical testing will be conducted, focusing on detecting the resistance value and tolerance, and also conducting visual inspections of the appearance to ensure that each product meets the established performance standards and no substandard products are produced.

Core strength of our company

As a legally certified manufacturer in China, RST Electric has been dedicated to the production of Open Air Current Sensing Resistors for over 10 years. By focusing on the specialized field, it has demonstrated its professional capabilities and become a trusted choice for global customers.

RST Electric achieves full-process autonomous control. From material selection of metal alloys, component forming, welding to final product inspection, all tasks are independently completed by the internal team. Each step is strictly controlled to ensure stable and uniform product quality. We adhere to the factory direct supply model, with transparent cost structure and no any additional price hikes at any intermediate links. This enables customers to purchase high-quality OAR series resistors at more reasonable costs.

RST Electric has an ISO 9001-certified production base, equipped with a dedicated production line for low-ohm precision resistors. Each product undergoes 100% electrical testing, and internal thermal performance and reliability tests are also conducted to verify the effectiveness of open cooling. An experienced engineering team focuses on current detection solutions in the power electronics field and can precisely meet customer needs.

RST Electric's products are exported to 40+ countries including Germany, the United States, Japan, South Korea, and Brazil. It is a reliable supplier for global power manufacturers, automotive electronics enterprises, and industrial drive manufacturers. It has accumulated rich experience in ultra-low resistance and high-precision current detection applications.

RST Electric offers full customization. The power, resistance value, tolerance, material, wire forming and wire coating can all be customized as per customer requirements. At the same time, it provides a flexible delivery period of 10 to 25 working days, complete technical documentation, 12-month warranty and remote fault diagnosis and technical support. It ensures the entire process of customer procurement and product integration.