Model CTR9000

Primary-standard resistance thermometry bridge

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  • High-performance AC resistance thermometry bridge for very accurate temperature measurements
  • Primary thermometer calibration for national and accredited laboratories, commercial temperature measurement and calibration applications

Special features

  • Accuracy: < ±20 ppb (±5 μK 1)), optional < ±0.1 ppm (±25 μK 1))
  • Resolution: 1 ppb (0.25 μK 1)), optional 0.1 ppm (25 μK 1))
  • Fast measurement time (2 seconds balance)
  • Differential and absolute measurement
  • Warm-up time < 30 seconds

1) 25 Ω SPRT referred to a 25 Ω reference resistor


In metrology, the most important consideration is the quality of the fundamental measurement. The bridge technology from ASL represents the peak of performance in resistance thermometer measurement. It exploits the inherent advantages of AC bridge technology to maintain repeatable measurements of highest precision under practical operating conditions.

The model CTR9000 primary-standard resistance thermometry bridge is designed specifically for resistance thermometry to provide the best possible accuracy.

The 25/30 2) Hz or 75/90 2) Hz operating frequency provides fast, continuous measurement with high immunity to thermal EMF errors and supply frequency noise sources.

Practical measurements involve cables, connectors and imperfect operating environments. The CTR9000 achieves its full specification under a wide range of real operating conditions. AC bridge technology will always outperform measurements

made using DC technology with slow current reversal. These benefits are inherent to the fundamentals of electrical measurement and not just the implementation.

2) 60 Hz supply frequency

Primary-standard resistance thermometry bridge
  • Primary-standard resistance thermometry bridge

Advantages of AC resistance thermometry bridges

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