Precision resistors for very high accuracy

Measuring Resistors

  • Very high accuracy
  • Wide resistance range
  • Wired or metal film resistors
  • Extended temperature range
  • Description
  • Good to know
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Measuring resistors – high precision measuring characteristics

The measuring resistors in our offer met the highest quality standards. For example, thanks to multilayer windings of the ASTRO2 series resistor wire, extremely low inductance and increased stability of the resistance value is achieved. Our range offers models which, thanks to their low inherent noise, can be used in almost all areas of electronics. Particularly suitable are applications such as switching and control systems as well as measuring circuits. Furthermore, the low inductance and capacitance-free design of our UMX measuring resistors should be emphasized. These are preferably used in applications with high requirements on resistance tolerance as well as TC values. Also the acquisition of temperature or data, the use in test and measurement equipment as well as operational amplifiers with high accuracy succeed optimally with this series. In difficult environmental conditions our models of the MR series deliver highly reliable and extremely stable results. They are used in applications with high demands on long-term stability, such as weighing systems, steering and control systems, as well as a wide range of applications in medical technology and automation.

What is a measuring resistor?
Measuring resistors are ohmic resistors that have to meet the particularly high requirements in precision measurement technology. Therefore, they are precision resistors without exception. They are used for current and voltage measurement and are usually used in voltage divider circuits. Due to their accurate, stable resistance value, currents can be measured accurately if the voltage is known exactly (and vice versa). Depending on the application, different types of precision resistors are suitable for this task. Among them, however, are special power resistors and shunt resistors suitable for applications at high voltages and/or currents. The design can be very different and the term measuring resistor is used when the application revolves around solving a measurement task.

Tips for measuring resistors
The range of measuring resistors and the field of application are so broad that a simple statement as to which resistor is suitable when cannot be given a general answer. One can generalize the technological characteristics conditionally by the respective design.
Measuring resistors with resistance elements made of wire (i.e. wire wound resistors) have an inductance due to their design, which restricts their use at high frequencies. Special winding techniques are used here in an attempt to significantly reduce this effect at the relevant frequencies in the application. They offer the best possibility of achieving an exact resistance value with very good resistance tolerances. This advantage therefore comes into play above all when a particular value of total resistance has to be achieved that is not available as a standard product. However, if this is not required, metal foil and metal film resistors are usually the better choice today, since they do not exhibit these frequency effects. However, on the one hand the operating temperature range is limited compared to wire elements and not all of them are suitable for higher power consumption.

Features of a precision resistor
A precision resistor is, simply put, a more "accurate" resistor compared to conventional products available in bulk. In addition to the generally higher quality standard, the following main characteristics are decisive for the use of the term "precision resistor", depending on the design, in order to distinguish these resistors from "standard goods" or "mass-produced goods".

  • Much tighter resistance tolerances
  • Production of precise resistor values depending on requirements / function
  • Lower temperature coefficient (TK value)
  • Far better long-term behavior
  • Larger special temperature ranges (partly up to 300 °C)
  • Lower current noise
  • Suppression of inductance and/or capacitance effects
  • Special housings / connections Four-wire or Kelvin measurement method

 Depending on the technology and method, the better tolerance is achieved by material selection. Temperature coefficient, on the other hand, is consistently a material property. Better long-term performance is achieved by using high quality materials and by artificial aging or preloading.

Precision resistor types
In our portfolio for resistors you will find only fixed resistors. That is, our resistors are selected according to a fixed ohmic value. Variable resistors, if you will, are in our portfolio for potentiometers. However, we do not recommend using these products as variable resistors.
Basically, all our resistors are precision resistors because of their quality, function and grade. The tight resistance tolerances, exactly selectable ohmic values as well as the stability and long-term behavior clearly differentiate them from standard resistors.

Article No. Resistance range Tolerance Temp. coefficient Oper. temperature Feature/Option Images 3D Data sheet Order Wishlist
ASTRO2 0.01Ω - 6MΩ ±0.005% ±10ppm/°C -55 to +145°C Wirewound Order
ASTRO5 0.01Ω - 1MΩ ±0.005% ±10ppm/°C -55 to +145°C Wirewound Order
NC550 1Ω - 5MΩ ±0.05% ±3ppm/°C -25 to +125°C Metal film Order
UMX 10Ω - 1MΩ ±0.05% ±5ppm/°C -55 to +125°C Metal film Order
MZH 100Ω - 100kΩ ±0.005% ±0.6ppm/°C -65 to +150°C Metal foil Order
MR 1Ω -400kΩ ±0.005% ±1ppm/°C -65 to +175°C Metal foil Order