AccuMac AM1762 Operating Manual

AM1760/1762 Secondary Standard

Platinum Resistance Thermometer

User’s Guide

Please download the latest version at www.accumac.com

Rev. 201609V3

AM1760/1762 Secondary SPRT User’s Guide

Table of Contents

Before you start ---- Warnings & Cautions ........................................................................ 2

1 Introduction ................................................................................................................ 3

1.1

1.2

1.3

2 Specifications .............................................................................................................. 4

2.1

3 General Operations .................................................................................................... 5

3.1

3.2

3.3

3.4

3.5

3.6

4 Care and Handling Guidelines ................................................................................... 7

5 Troubleshooting .......................................................................................................... 8

5.1

5.2

6 Limited Warranty & Limitation of Liability ............................................................... 9

Main Application ................................................................................................ 3

Main Features ..................................................................................................... 3

Calibrations ......................................................................................................... 3

Specifications ...................................................................................................... 4

Connecting to the readout device ........................................................................ 5

Drive Current ...................................................................................................... 5

Stability of Readings ........................................................................................... 5

Immersion Requirements .................................................................................... 5

Thermal EMF ...................................................................................................... 6

Over heating ........................................................................................................ 6

Troubleshooting .................................................................................................. 8

Problem Causes and Solutions ............................................................................ 8

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AM1760/1762 Secondary SPRT User’s Guide

Before you start ---- Warnings & Cautions

 Warnings: Follow these guidelines to avoid personal injury:

1. Only use this instrument in the manufacture specified

temperature range.

2. The handle of this instrument can become hot when it is used

to measure high temperatures for extended periods of time.

3. DO NOT submerge PRT handle when taking measurement.

4. DO NOT use this instrument to measure the temperature of

any hazardous live component.

5. Follow all other safety guidelines listed in this user’s guide.

 Cautions: Follow these guidelines to avoid possible damage to

the instrument:

1. Avoid mechanical shocks. DO NOT drop or slam the probe in

any way. This will cause damage to the probe internally and
affect its calibration and accuracy.

2. Read Section entitled “Care and Handling Guidelines” before

removing the PRT from the shipping box. Incorrect handling
can damage the PRT and void the warranty.

3. Keep the shipping container in case it is necessary to ship the

PRT. Incorrect packaging of the PRT for shipment can cause
irreparable damage.

4. Calibration equipment should only be used by trained

personnel.

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AM1760/1762 Secondary SPRT User’s Guide

1 Introduction

1.1 Main Application

AM1760/1762 Secondary Standard Platinum Resistance Thermometer
(SPRT) interpolates temperature in the range from -200 °C to 670 °C
on the International Temperature Scale of 1990 (ITS-90). It works
together with a readout device to measure temperature or change of
temperature. It is designed as a secondary standard thermometer to
calibrate other thermometers and to measure temperature precisely in
metrology labs.

1.2 Main Features

 High accuracy: ±0.006 ºC at 0.01 °C
 Temperature range: : -200 °C to 670 °C
 Rtpw Drift < 4 mK after 100 hours at 661 °C

1.3 Calibrations

As a temperature reference standard, each SPRT must be calibrated.
Manufacturer recommends calibration interval to be one year. In
between annual calibrations, user can check the drift rate by
comparing Rtpw against the last calibration results. Refer to
specifications section for normal drift rate.

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AM1760/1762 Secondary SPRT User’s Guide

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2 Specifications

2.1 Specifications

Temperature Range
Resistance at 0 °C

Temperature Coefficient
Accuracy

Drift*
Short Term Stability
Thermal Shock

Self-heating
Response Time

Measurement Current
Sensor Length
Sensor Location
Insulation Resistance
Sheath Material
Dimension

External Leads
Handle Dimension

Handle Temperature
Range**
Optional Calibration

*Long-term drift rate is for reference only. It could be affected by such facts as handling, application, and maintenance, etc.
**Handle temperature outside this range will cause damage to the probe.

-200 °C to 670 °C
1760 - Nominal 100 Ω
1762 – Nominal 25 Ω

0.003925 Ω/ Ω/°C
±0.007 °C at -196 °C
±0.006 °C at 0.01 °C
±0.015 °C at 420 °C
±0.025 °C at 661 °C
±0.004 °C at TPW after 100 hours at 661 °C
±0.002 °C
±0.002 °C after 10 times thermal cycles from minimum to
maximum temperatures

0.0015 °C at 1 mA current
9 seconds for 63% response to step change in water moving
at 3 feet per second
1 mA
42 mm
5 mm from tip
>1000 MΩ at room temperature
Inconeltm
1760/1762-12: 0.25 inch X 12 inch (6.35 mm X 305 mm)
1760/1762-20: 0.25inch X 20 inch (6.35 mm X 500 mm)
Teflon
15 mm (OD) X 65 mm (L)

-50 °C to 180 °C

NIST traceable calibration and data available per request:
Ordering # 5007

– insulated copper wire, 4 leads, 2.5 meters

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AM1760/1762 Secondary SPRT User’s Guide

3 General Operations

3.1 Connecting to the readout device

The AM1760/1762 is equipped with a four-wire cable (see Figure 1).
Four lead wires are used to cancel lead wire resistance. For best
results, the readout device should be equipped to handle four-terminal
resistors. The lead wires can be distinguished by insulation colors.
Lead wire pairs attached to each end of the sensor are identified by
red/black and white/blue insulation.

White Red

Black Blue

Figure1

3.2 Drive Current

AccuMac recommends 1mA as drive current to ensure the best
measurement.

3.3 Stability of Readings

To achieve the best accuracy, allow sufficient time for SPRT to
stabilize before taking the readings.

3.4 Immersion Requirements

Stem effect can cause measurement errors due to heat lost or gained
by the sensing element through the thermometer stem. To minimize
the error, appropriate immersion depths are required. A practical way
to determine the minimum immersion depths is to change the depth

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AM1760/1762 Secondary SPRT User’s Guide

gradually until the readings have significant changes after
stabilization.

Do not submerge SPRT handle when taking measurement.

3.5 Thermal EMF

Each AccuMac PRT has gone through an annealing process and
stability test to minimize the thermal EMF, which is caused by either
impurities of sensing element or temperature differentials at lead wires
connection point.

3.6 Over Heating

The sensing element of AM1760/1762 SPRT is sealed inside an
Inconeltm sheath to ensure the best stability and repeatability. The seal
can be breached if the SPRT is over heated for an extended period of
time.

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AM1760/1762 Secondary SPRT User’s Guide

4 Care and Handling Guidelines

1. DO NOT subject the PRT to any physical shocks and vibrations.
a. When not using the PRT, keep it in a place that’s not prone

to drop, slam, bang, vibration or other strong physical
contacts. Use a protective box or a carrying case whenever
possible.

b. When shipping the PRT, use protective box and other

protective packaging materials to minimize mechanical
shocks as much as possible.

c. When using dry blocks, make sure the well diameter is

appropriate to allow the PRT move up and down smoothly.

2. DO NOT subject the PRT to any contaminations.
a. Keep the PRT as clean as possible. Avoid contaminations

as much as possible.

3. DO NOT over heat.
a. Do not use PRT above the manufacture specified

temperature range.

b. Do not expose the PRT handle and lead wires to extreme

temperatures.

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AM1760/1762 Secondary SPRT User’s Guide

5 Troubleshooting

5.1 Troubleshooting

If the PRT functions abnormally, it could be caused by several
possible problem conditions that are described in this section. Try the
solutions recommended and if the problems are still not solved,
contact manufacture for warranty or repair service. Be sure to have the
model number and serial number of your PRT available.

5.2 Problem Causes and Solutions

a. R0/Rtpw becomes higher significantly. This is likely caused by

mechanical shocks. The PRT should be annealed to release the
stress of platinum wires and to recover R0/Rtpw value. Measure
R0/Rtpw of the PRT after annealing to verify.

b. R0/Rtpw unstable during the measurement. This is likely caused

either by bad connections or sensor coils short. Check the
connections first and if the connections are good, the PRT may
be damaged.

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AM1760/1762 Secondary SPRT User’s Guide

6 Limited Warranty & Limitation of Liability

The material contained in this document is provided “as is,” and is
subject to being changed, without notice, in future editions. AccuMac
shall not be liable for errors or for incidental or consequential
damages in connection with the furnishing, use, or performance of this
document or of any information contained herein. Should AccuMac
and the user have a separate written agreement with warranty terms
covering the material in this document that conflict with these terms,
the warranty terms in the separate agreement shall control.

Each product from AccuMac Corporation is warranted to be free from
defects in material and workmanship under normal use and service.
The warranty period is 1 year for the Platinum Resistance
Thermometer. The warranty period begins on the date of the shipment.
Parts, product repairs, and services are warranted for 90 days. The
warranty extends only to the original buyer or end-user customer of an
AccuMac authorized reseller. The warranty will not extended to
products that have been misused, altered, neglected, or damaged by
accident or abnormal conditions of operation or handling.

To obtain warranty service, contact AccuMac Corporation at:

90 N William Dillard Drive C-107
Gilbert, AZ 85233
USA
Tel: [phone]
Email: [e-mail]

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