The MicroK family of precision thermometers uses a completely new measurement technique to achieve accuracies better than 0.02 ppm.
With four models to suit all levels of temperature metrology from National Measurement Institutes to those wanting a solution to make low uncertainty temperature measurements in a range of applications.
In addition to making the best resistance measurements the MicroK makes high accuracy thermocouple measurements with a voltage uncertainty of
First introduced in 2006 the MicroK has proven use at the world’s leading NMIs and many commercial laboratories. After years of experience and success we now introduce new models with even better performance and new features. All microK models now include IEEE-488 General Purpose Interface Bus as well as RS232 and USB. The microK 70 and microK 125 also feature an Ethernet port and can be monitored and controlled across a LAN.
When used with a 0°C cold junction reference unit, or by measuring the junction temperature with a PRT on another channel, the instrument is capable of low uncertainty precision thermocouple measurements, with a voltage uncertainty of just 0.25μV, equivalent to 0.01°C with a Platinum / Gold Thermocouple at 1000°C.
The instruments in the MicroK range offer performance characteristics and features which are simply not available elsewhere. Comparable instruments available internationally do not achieve the same accuracy or stability (zero drift characteristics with SPRT measurements are not obtainable in any other instrument), other instruments do not support the same variety of sensors, and offer considerably less operational features. The MicroK family uses solid state construction with no potentiometers or relays, which ensures long term reliability and low cost of ownership.
Highly stable
The inherently stable “substitution technique” used in the MicroK means that it achieves zero drift for resistance measurements and only 3 ppm/year for voltage measurements so you can be confident in your measurements between calibrations.
Versatile
This is the only instrument of its type that works with SPRTs, thermocouples and thermistors, so you only need to purchase one product for your thermometry application rather than two or more instruments.
Easy to use
The MicroK includes a comprehensive range of features, including direct reading in temperature for all sensor types, data logging, easy export of data to Excel and graphing facilities. Despite its sophistication the MicroK is very easy to use. The built-in full 6.4” full VGA colour touch screen, powered by the Windows CE operating system provides a familiar and powerful operator interface so you can get on with making measurements rather than learning how to control the instrument.
| Parameter | MicroK 70 | MicroK 125 | MicroK 250 | MicroK 500 |
| Accuracy whole range (SPRT Ro ≥ 2.5 Ω) (1) |
0.07 ppm | 0.125 ppm | 0.25 ppm | 0.5 ppm |
| Accuracy ratio 0.95 to 1.05 (2) Equivalent temperature accuracy (2) |
0.017 ppm 0.017 mK |
0.03 ppm 0.03 mK |
0.06 ppm 0.06 mK |
0.125 ppm 0.125 mK |
| Resolution | 0.001 mK | 0.001 mK | 0.01 mK | 0.01 mK |
| Resolution voltage | 10 nV | 10 nV | 10 nV | 10 nV |
| Stability | 0 ppm/year (3) | 0 ppm/year (3) | 0 ppm/year (3) | 0 ppm/year (3) |
| Tc (resistance ratio) (4) | 0 ppm/°C (3) | 0 ppm/°C (3) | 0 ppm/°C (3) | 0 ppm/°C (3) |
| Resistance range | 0-100 kΩ | 0-100 kΩ | 0-500 kΩ | 0-500 kΩ |
| Voltage range (thermocouples) | ± 125 mV | ± 125 mV | ± 125 mV | ± 125 mV |
| Internal resistance standards | 25, 100, 400 Ω | 25, 100, 400 Ω | 1, 10, 25, 100, 400 Ω | 1, 10, 25, 100, 400 Ω |
| Internal standard resistor stability | TCR < 0.05 ppm/°C Annual stability: < 2 ppm/year |
1, 10 Ω: 25,100,400 Ω: |
(1) Over whole range of SPRT, -200°C to 962°C. For Ro=0.25 Ω increased by a factor of 2.5
(2) E.g.: 25 Ω SPRT with 25 Ω standard resistor at Water Triple Point or with direct comparison of similar SPRTs.
(3) The MicroK uses a “substitution technique” in which the Device-Under-Test and the Reference are successively switched into the same position in the measuring circuit. This means that the stability of resistance ratio measurements is immeasurably small.
(4) Using external reference resistors.
Further features
| Accuracy in thermocouples | Voltage uncertainty: 250 nV Range: 0-20 mV Equivalent to 0.01°C for Gold Platinum thermocouples at 1000°C |
| Measurement time (per channel) | Resistance: < 2 s (1 s using the RS232 or GPIB interface) Voltage: < 1 s (0.5 s using the RS232 or GPIB interface) |
| Cold junction mode | External and remote with PRT |
| MicrosKanner | Expands MicroK with up to 90 expandable channels |
| Sensor current | 0-10 mA in 3 ranges: Range 1: 0-0.1 mA Accuracy: ±0.4% RDG + ±70 nA Resolution: 28 nA Range 2: 0.1-1 mA Accuracy: ±0.4% RDG + ±0.7 μA Resolution: 280 nA Range 3: 1-10 mA Accuracy: ±0.4% RDG + ±7 μA Resolution: 2.8 μA |
| Keep-warm current | 0-10 mA, adjustable for each channel Accuracy: ±0.4% RDG + ±7 μA Resolution: 2.8 μA |
General specifications
| Size | 520 x 166 x 300 mm |
| Weight | MicroK 70 / 125: 13.3 kg MicroK 250 / 500: 12.4 kg |
| Display | Colour TFT LCD 640 x 480, 6.4” VGA Display unit: °C, °F, K, Ω, mV |
| Power supply | 88 / 264 VAC, 47/63 Hz MicroK 70 / 125: 25 W maximum, 1.5 A (RMS) maximum MicroK 250 / 500: 20 W maximum, 1.5 A (RMS) maximum |
| Communication ports | All models: RS 232, GPIB, USB MicroK 70 / 125: Ethernet |
| Storage capacity | 2 Gb > 4 years measurements stored with date and time on internal memory |
Environmental specifications
| Reference range | +15 to +30°C (RH: 10 to 80% w/o condensing |
| Operating reference range | 0 to +40°C (RH: 0 to 95% w/o condensing) |
