Mineral insulated thermocouple cables and thermocouples

Establishes the requirements for mineral insulated thermocouple cables and for mineral insulated thermocouples but does not specify cold end seals, terminations, connections and other accessories. Deals only with cables and thermocouples having one pair of base-metal conductors and is intended for use in general industrial applications.

Mantelthermoelement-Leitungen und Mantelthermoelemente

Câbles et couples thermoélectriques à isolation minérale dits "chemisés"

Spécifie les caractéristiques des câbles thermoélecteriques dits "chemisés" et des couples thermoélectriques dits "chemisés" mais ne caractérise pas l'obturation de l'extrémité froide, les terminaisons, les connexions et autres accessoires. S'applique exclusivement aux câbles et couples thermoélectriques chemisés ne comprenant qu'une seule paire de conducteurs et généralement utilisés dans les applications industrielles.

Mineral insulated thermocouple cables and thermocouples (IEC 61515:1995)

General Information

Publication Date
Technical Committee
Drafting Committee
Parallel Committee
Current Stage
6060 - Document made available
Start Date
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SIST EN 61515:1998
Mineral insulated thermocouple cables and thermocouples (IEC 61515:1995)
Mineral insulated thermocouple cables and thermocouples
Mantelthermoelement-Leitungen und Mantelthermoelemente
Câbles et couples thermoélectriques à isolation minérale dits chemisés
Ta slovenski standard je istoveten z: EN 61515:1996
17.200.20 Instrumenti za merjenje Temperature-measuring
temperature instruments
SIST EN 61515:1998 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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Première édition
First edition
Câbles et couples thermoélectriques à
isolation minérale dits «chemisés»
Mineral insulated thermocouple cables
and thermocouples
© CD 1995 Droits de reproduction réservés — Copyright — all rights reserved

Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in

utilisée sous quelque forme que ce soit et par aucun pro- any form or by any means, electronic or mechanical,

cédé, électronique ou mécanique, y compris la photocopie et including photocopying and microfilm, without permission

les microfilms, sans raccord écrit de l'éditeur. in writing from the publisher.

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1515 ©IEC:1995 — 3 —
1 General
2 Definitions
Mineral insulated thermocouple cables
17 Mineral insulated thermocouples
Annex A
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1515 ©IEC:1995 – 5 –

The IEC (International Electrotechnical Commission) is a worldwide organization for standardization

comprising all national electrotechnical committees (IEC National Committees). The object of the IEC is to

promote international cooperation on all questions concerning standardization in the electrical and

electronic fields. To this end and in addition to other activities, the IEC publishes International Standards.

Their preparation is entrusted to technical committees; any IEC National Committee interested in

the subject dealt with may participate in this preparatory work. International, governmental and

non-governmental organizations liaising with the IEC also participate in this preparation. The IEC

collaborates closely with the International Organization for Standardization (ISO) in accordance with

conditions determined by agreement between the two organizations.

The formal decisions or agreements of the IEC on technical matters, prepared by technical committees on

which all the National Committees having a special interest therein are represented, express, as nearly as

possible, an international consensus of opinion on the subjects dealt with.

3) They have the form of recommendations for international use published in the form of standards, technical

reports or guides and they are accepted by the National Committees in that sense.

4) In order to promote international unification, IEC National Committees undertake to apply IEC International

Standards transparently to the maximum extent possible in their national and regional standards. Any

divergence between the IEC Standard and the corresponding national or regional standard shall be clearly

indicated in the latter.

International Standard IEC 1515 has been prepared by sub-committee 65B: Devices, of

IEC technical committee 65: Industrial-process measurement and control.
The text of this standard is based on the following documents:
DIS Report on voting
65B/227/DIS 65/195/RVD

Full information on the voting for the approval of this standard can be found in the report

on voting indicated in the above table.
Annex A forms an integral pa rt of this standard.
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1515 ©IEC:1995 - 7 -
1 General
1.1 Scope and object

This International Standard establishes the requirements for mineral insulated thermo-

couple cables and for mineral insulated thermocouples but does not specify cold end

seals, terminations, connections and other accessories. This standard deals only with

cables and thermocouples having one pair of base-metal conductors and is intended for

use in general industrial applications.
1 This standard does not deal with precious metal cables and thermocouples.

2 Mineral insulated cables and thermocouples also are available with more than one pair of conductors

or where there is one conductor and a sheath. In these cases the detailed prescriptions in this standard —

e.g. the dimensions — may not necessarily apply.

3 The special requirements for nuclear primary loop applications are dealt with in other standards.

1.2 Normative references

The following normative documents contain provisions which, through reference in this

text, constitute provisions of this International Standard. At the time of publication, the

editions indicated were valid. All normative documents are subject to revision, and parties

to agreements based on this International Standard are encouraged to investigate the

possibility of applying the most recent editions of the normative documents indicated

below. Members of IEC and ISO maintain registers of currently valid International

IEC/DIS 584-1, Thermocouples - Part 1: Reference tables')
IEC 584-2: 1982, Thermocouples - Part 2: Tolerances
2 Definitions

For the purposes of this International Standard, the following definitions apply.

2.1 mineral insulated thermocouple cables: Bendable metal sheathed thermocouple
cables with conductors insulated by compacted metal oxide.
thermocouples: Thermocouples made from mineral insulated
2.2 mineral insulated
thermocouple cables.
2.3 measuring junction: Junction subjected to the temperature to be measured.

1) At present, at the stage of Draft International Standard for the second edition.

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- 9 -
1515 ©IEC:1995

2.4 earthed junction: Measuring junction electrically connected to the metal sheath.

2.5 Insulated junction: Measuring junction electrically insulated from the metal sheath.

3 Mineral insulated thermocouple cables
3.1 Dimensions

Outside diameter, sheath thickness and conductor diameter dimensions shall be as stated

in table 1.
D = outside diameter
C = conductor diameter
S = sheath wall thickness
I = insulation thickness
Figure 1 - Transverse section of a cable
Table 1 - Dimensions
Sheath wall Diameter of
Outside diameter
Insulation thickness (1)
of cable (D), thickness (S) conductor (C)
minimum minimum
nominal ± tolerance
mm mm
mm mm
0,5 ± 0,025 0,05 0,08 0,04
1,0 t 0,025 0,10 0,15 0,08
0,15 0,23
1,5 ± 0,025 0,12
2,0 ± 0,025 0,20 0,30 0,16
0,30 0,45
3,0 ± 0,030 0,24
4,5 t 0,045 0,45 0,68 0,36
0,60 0,90 0,48
6,0 ± 0,060
8,0 ± 0,080 0,80 1,20 0,64
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1515 ©IEC:1995 - 11 -
3.2 General requirements
3.2.1 Materials Sheaths

Sheaths shall be of austenitic stainless steel, heat resistant NiCr (Fe) alloy or other

material to specifications agreed between manufacturer and user. Some commonly used

sheath materials are listed in table 2. Conductors

Conductors (thermoelectric elements) shall be those forming thermocouple types T, J, E,

K and N as specified in IEC 584-1.

It should be noted that not all combinations of sheath materials and conductor materials

can be manufactured. Insulation

The insulation shall consist of compacted powdered magnesia or alumina with a purity of

at least 96 %. The electrical properties of the insulation shall meet the insulation

resistance test requirements of
Upper temperature limits
The recommended maximum operating temperatures for some commonly used sheath

materials are indicated in table 2 for each thermocouple type. For particularly corrosive

atmospheres, the indicated values may not apply and the manufacturer's recom-
mendations should be followed.
Table 2 - Recommended maximum operating temperatures
Sheath TC-type
NiCr alloy Steel Steel
76 Ni, 15 Cr, Fe 25 Cr, 20 Ni 18 Cr, 8 Ni
°C °C °C
T – – 400
E 800 800 800
J 750 750 750
K 1100 1 100 800
N 1 100 1 100 800
Bending radius
r of five times its outside dia-
The cable shall be capable of being bent through a radius
meter D (r= 5D) without visible damage.
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1515©IEC:1995 – 13 –
3.2.2 Electrical characteristics EMF values

EMF values shall comply with IEC 584-1 with initial calibration tolerance values as

specified for base metal conductors in IEC 584-2. Insulation resistance
Insulation resistance shall be measured between each wire and sheath and between

wires, at test voltages of 75 V ± 25 V d.c. for outside diameters 55.1,5 mm and 500 V ± 50 V

d.c. for outside diameters >1,5 mm.

Sample length, temperature conditions and insulation resistance values expressed in

MS2 m for testing at ambient and elevated temperatures shall be as given in table 3.

Table 3 – Insulation resistance values at ambient and elevated temperatures
Minimum immersed
Minimum Insulation
length at test
Test temperature
m °c M52m
1 1 000
Ambient temperature 20 ± 15
Elevated temperature
0,5 500 ± 15 5
E, K,

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