Resistance thermometer 159 series

Pt100RTDwith LCD graphic display

Overview
Resistance ratio or absolute resistance measurements: choose either mode. The 1595A achieves ratio uncertainty as good as 0.06 ppm near unity. The instruments convert absolute resistance to temperature and display in °C, °F or K using temperature-controlled internal reference resistors (1 Ω, 10 Ω, 25 Ω, 100 Ω, 10 kΩ). Internal references are oven-controlled at 30 °C with stability ~10 mK; 24-hour stability better than 0.25 ppm and one-year absolute accuracy 4 ppm.

Low measurement noise
Patent-pending design reduces electrical noise and random error through simultaneous Rx/Rs measurements with current reversal and averaging, dual parallel ADCs and passive/active filtering. Typical uncertainty contribution due to measurement noise can be as low as 0.00002 °C for appropriate sensors and conditions.

High measurement speed
Sample rates as fast as 1 s (full accuracy with a 2 s sample rate). User control of sample rate and timing parameters to match application needs; remote viewing and device control via Ethernet.

Ratio self-calibration
Automated procedure tests or calibrates resistance-ratio linearity using internal temperature-controlled resistors. The routine performs eight ratio tests, reports linearity errors, typically completes in ~30 minutes and can detect measurement-circuit defects. Password-protected option allows applying alignment offsets.

Key features

• Ratio accuracy as good as 0.06 ppm (1595A) for ratios near unity.
• Compatible with SPRTs, PRTs, RTDs and thermistors; resistance range 0 Ω to 500 kΩ.
• Ratio self-calibration to verify/calibrate linearity without external equipment.
• Temperature-controlled internal reference resistors: 1 Ω, 10 Ω, 25 Ω, 100 Ω, 10 kΩ (oven at 30 °C).
• Automatic zero-power measurements and calibrated sensing currents to reduce instrument uncertainty.
• Sample rates down to 1 s; front panel four PRT/thermistor inputs; rear two dedicated RS inputs; data logging capacity ~80,000 readings.

Representative specifications
Measurement capability: 4-wire PRT, thermistor, resistance, resistance ratio.
Input resistance range: 0 to 500 kΩ.
Ratio range: 0 to 10.
Accepted external RS range: 1 Ω to 10 kΩ.
Internal RS: 1 Ω, 10 Ω, 25 Ω, 100 Ω, 10 kΩ.
Display units: Rx/Rs, K, °C, °F, Ω; resolution 0.1 to 0.000001.
Sample periods (s): 1, 2, 5, 10 (2 s required for full accuracy).
Statistics: average, std dev, SE of mean, max, min, diff, peak-peak, delta, N.
Computer communications: RS-232, USB, IEEE-488, Ethernet; full VGA LCD.

Manuals & resources
User manual, reference guide, data sheet, firmware updates and calibration resources available.