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Super-Thermometer Readouts - 1575A and 1590

 1575A and 1590 reference thermometer readouts

Features

  • Accuracy to 4 ppm (0.001 °C) or 1 ppm (0.00025 °C)
  • Bridge-level performance at less than half the cost
  • Accepts 0.25-ohm through 100-ohm SPRTs plus thermistors
  • Includes all temperature functions and stores setups

Specifications                              1575A 

1590 

 

Nominal
Resistance

Accuracy (of indicated value)

Equivalent Temp. Value, at 0 °C

Nominal
Resistance

Accuracy (of indicated value)

Equivalent Temp. Value, at 0 °C 

Transfer Accuracy (using external reference resistor) 

0.25 W
2.5 W
25 W
100 W
10 KW 

40 ppm
20 ppm
4 ppm
4 ppm
10 ppm 

0.01 °C
0.005 °C
0.001 °C
0.001 °C
0.00025 °C
(thermistor at 25 °C) 

0.25 W
2.5 W
25 W
100 W
10 KW 

20 ppm
5 ppm
1 ppm
1 ppm
5 ppm 

0.005 °C
0.00125 °C
0.00025 °C
0.00025 °C
0.000125 °C
(thermistor at 25 °C) 

Absolute Accuracy (using internal reference resistor) 

0.25 W
2.5 W
25 W
100 W
10 KW 

100 ppm
40 ppm
8 ppm
8 ppm
20 ppm 

0.025 °C
0.01 °C
0.002 °C
0.002 °C
0.0005 °C
(thermistor at 25 °C) 

0.25 W
2.5 W
25 W
100 W
10 KW 

40 ppm
20 ppm
6 ppm
6 ppm
10 ppm 

0.01 °C
0.005 °C
0.0015 °C
0.0015 °C
0.00025 °C
(thermistor at 25 °C) 

Typical Resolution 

0.25 W
2.5 W
25 W
100 W
10 KW 

10 ppm
5 ppm
1 ppm
1 ppm
3 ppm 

0.0025 °C
0.00125 °C
0.00025 °C
0.00025 °C
0.000075 °C
(thermistor at 25 °C) 

0.25 W
2.5 W
25 W
100 W
10 KW 

10 ppm
2 ppm
0.5 ppm
0.5 ppm
2 ppm 

0.0025 °C
0.0005 °C
0.000125 °C
0.000125 °C
0.00005 °C
(thermistor at 25 °C) 

Resistance Range 

0 W to 500 KW 

Internal Reference Resistors 

1 W, 10 W, 100 W, 10 KW 

Minimum Measurement Period 

2 seconds 

Current Source 

0.001 mA to 20 mA, programmable 

Analog Output 

–5 to +5 V 

Display 

Monochrome LCD with CCFT backlight 

Color LCD with CCFT backlight 

Power 

100–125/200–250 V ac (user switchable), 50/60 Hz, 1 A 

Size/Weight 

178 mm H x 516 mm W x 320 mm D (7.0 x 20.3 x 12.6 in) / 16 kg (35 lb) 

Calibration 

Includes NIST-traceable accredited calibration 

 

Hart’s Super-Thermometers are recognized in metrology laboratories around the world for their ease of use and reliable accuracy. These are high accuracy reference thermometers. Model 1575A Super-Thermometer is accurate to 0.001 °C. The Model 1590 Super-Thermometer II is accurate to 0.00025 °C, or 1 ppm. 

Both Super-Thermometers are perfectly suited for SPRT calibrations. These are the best lab instruments to take advantage of SPRT accuracy. They’re easy to use, they read temperature directly, they have automated data collection, they automatically calculate constants for ITS-90, and both of them are priced at less than half the price of the competitors’ resistance bridges. 

Of course, there’s more. 

Bridges 

Resistance bridges are one of the most expensive pieces of lab equipment you can buy. Most sell for $30,000 to $50,000. The resistance bridge market is very small, and there’s hardly any competition. There’s nothing to control the price except your willingness to pay. 

Resistance bridges are difficult to use. Their learning curve is long and complex, which means you’ll spend plenty of time learning to master one. Time spent learning costs you money, and costs multiply if you have to train other people! 

So why buy a bridge if you have a legitimate alternative? 

If 1 ppm accuracy gets the job done, the easiest and cheapest way to do it is with one of Hart’s Super-Thermometers. 

1575A 

The 1575A Super-Thermometer is a best-selling thermometer because of its ease of use, high accuracy, built-in software, and reasonable price. Temperature is read directly on the display in your choice of scales. There are no manual resistance-to-temperature conversions. Resistance is converted to temperature for you using the ITS-90 algorithm in any one of the instrument’s ranges. Up to 16 independent sets of probe characterizations can be stored in the 1575A’s memory. Switch SPRTs and simply call up its reference identification number. Forget the extensive, time-consuming setup required by resistance bridges. Read the features common to both units and you’ll understand why each is a great buy. 

1590 

The 1590 Super-Thermometer II has all of the features of the 1575A, plus it has the unbeatable accuracy of 1 ppm and a color screen that tilts to create the best viewing angles. With all of these features, it’s still less than half the price of a bridge. 

In many labs with standards that require the use of bridges, Super-Thermometers have been accepted as an alternative to bridges because they are a combination of bridge technology and microprocessor-based solid-state electronics—and they’re much easier to use. 

Both Hart Super-Thermometers come with an accredited calibration. 

Accuracy 

In addition, resolution with a 25-ohm SPRT is 0.0001 °C. Comparison calibrations or calibrations against primary standard fixed points are easily performed. Both instruments have two channels for handling two probes at once. Display and record actual temperatures or choose to read the difference between the two directly from the screen. 

Both Super-Thermometers have their own on-board resistors. Each is a high-stability, low thermal coefficient, four-terminal resistor for each of the resistance ranges of the thermometer: 0.25 ohms, 2.5 ohms, 10 ohms, 25 ohms, 100 ohms, and thermistor ranges. Resistors are housed in an internal temperature-controlled oven. Can it get any better? 

Well, actually it does. 

DWF connectors  Available on most Hart reference thermometer readouts are the patented DWF thermometer and instrument connectors

Hart’s patented Model 2392 DWF Connector is unique in the industry (U.S. Patent 5,964,625). Each one is machined from solid brass and then plated with gold. DWF Connectors accept banana plugs, spade connectors, or bare wires. Banana plugs are inserted in the top. Bare wires go in one of the four side holes and are held in place by a spring-loaded pressure plate. Spade connectors are inserted between the top of the connector and pressure plate and are held in place the same as bare wire. The connections are solid and difficult to dislodge. Bare wire and spade connectors require nothing more than pushing the DWF Connector in. There’s nothing to screw down or tighten. 

(Back to Top)

Other features 

Super-Thermometers convert resistance to temperature using your choice of ITS-90 or IPTS-68. ITS-90 requires no conversions; just enter your coefficients directly. For IPTS-68 enter R0, ALPHA, DELTA, A4, and C4. Temperature can be converted from IPTS-68 to ITS-90 automatically at your request. Calendar-Van Dusen equations are also provided in an automated mode. 

Thermistor probes are characterized by coefficients of a logarithmic polynomial. Save money and use low-cost, rugged thermistor standards for ±0.001 °C accuracy in the low-temperature regions. Other thermometers don’t do all this. 

Measurements can be displayed as temperatures in °C, K, or °F and as resistance in ohms or a ratio of probe resistance to reference resistance. The current source is controllable between 0.001 mA and 15 mA with a resolution of 0.2 %. Integration time and digital filtering are programmable to optimize resolution, stability, and response. 

Datalogging and memory functions store measurements, and each thermometer has its own 3.5-inch disc drive for archiving data. The display is a backlit LCD for visual display of information. It has  an RS-232, an IEEE-488, and a parallel printer port. 

These Super-Thermometers are based on DC electronics, thus eliminating the problems with national lab certification for AC bridges and the removal of quadrature interference from AC-heated fixed-point furnaces. Read about the complete Theory of Operation of Hart Super-Thermometers at www.hartscientific.com 

Multiplexers  Multiplexers turn Hart reference thermometers into multi channel time savers.

If two channels aren’t enough, add 10 more with a Mighty-Mux featuring Hart’s handy DWF connectors. In fact, add up to 50 more channels to the 1590. 

The Model 2575 provides 10 more channels for use with a 1575. For the 1590, the Model 2590 Mighty-Mux II has a cascading ability that lets you have up to 50 channels by chaining more than one Mux together, and you can now set continuous constant current levels on each channel to avoid self-heating effects. Whatever your application, a Mighty-Mux will make it easier and more efficient. 

Both units have low thermal EMF relays that are hermetically sealed and magnetically shielded. You’re making true four-wire measurements with a floating guard and support for up to 20 mA of drive current. 

Super-Therometers vs. digital multimeters

Good eight-and-a-half-digit multimeters might give you accuracy to ±0.005 °C in the resistance measurement. However, DMMs require separate high-stability current sources, and you have to make EMF offsets, worry about a scheme to switch between forward and reverse current during the measurement, and devise a switch to get a second channel for an external standard resistor. 

Once you’ve done all of this, you still have to convert resistance to temperature with tedious manual calculations. 

Super-Thermometers do all of this automatically. 

Super-Thermometers vs. everything else

There really isn’t anything else to compare to the 1590 and 1575A. No other readout is this easy to use. You’ll be doing calibrations with it the first day you receive it, not the first day after the training program is over. 

Specifications - Muxes

Channels

2575: 10
2590: 10 per unit, cascade
          up to 5 units for 50
          channels

Connector

4-wire plug, floating guard

Terminals

Gold-plated Hart DWF Connectors

Relays

Low thermal EMF, hermetically sealed, magnetically shielded

Contact Resistance

< 0.1W

Isolation

1 x 1012 between relay legs

Channel Selection

Manual or auto

Current Capability

20 mA

Current Levels

1575: Current on active
          channel only
1590: Standby current 1 mA,
         0.5 mA, or 10 mA on
         all channels

Power

Via connection to 1575 or 1590

Size

20.3" W x 12.6" D x 7" H
(516 x 320 x 178 mm)

(Back to Top)

Super-Thermometers vs. digital multimeters 

Good eight-and-a-half-digit multimeters might give you accuracy to ±0.005 °C in the resistance measurement. However, DMMs require separate high-stability current sources, and you have to make EMF offsets, worry about a scheme to switch between forward and reverse current during the measurement, and devise a switch to get a second channel for an external standard resistor. 

Once you’ve done all of this, you still have to convert resistance to temperature with tedious manual calculations. 

Super-Thermometers do all of this automatically. 

Super-Thermometers vs. everything else 

There really isn’t anything else to compare to the 1590 and 1575A. No other readout is this easy to use. You’ll be doing calibrations with it the first day you receive it, not the first day after the training program is over. 

(Back to Top)

Ordering Information 
1575A 

Super-Thermometer 

2575 

Multiplexer, 1575 

1590 

Super-Thermometer II 

2590 

Multiplexer, 1590 

742A-25 

Standard DC Resistor, 25W 

742A-100 

Standard DC Resistor, 100W 

Downloads

Right click one of the following links and “Save Target As ...” to download the catalog pages/data sheet or a product User's Guide in Acrobat (.pdf)  format.

Use our feedback form for more information on these or other Fluke reference thermometers.

 

  
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