Jumo 906121 Platinum-Chip Temperature Sensors with Conn Manuel d'utilisateur télécharger pdf

2009-07-07/00411240

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JUMO GmbH & Co. KG

Delivery address: Mackenrodtstraße 14,

36039 Fulda, Germany

Postal address:

36035 Fulda, Germany

Phone: +49 661 6003-0

Fax: +49 661 6003-607

E-mail: [email protected]

Internet: www.jumo.net

JUMO Instrument Co. Ltd.

JUMO House

Temple Bank, Riverway

Harlow - Essex CM20 2DY, UK

Phone: +44 1279 63 55 33

Fax: +44 1279 63 52 62

E-mail: [email protected]

Internet: www.jumo.co.uk

JUMO Process Control, Inc.

8 Technology Boulevard

Canastota, NY 13032, USA

Phone: 315-697-JUMO

1-800-554-JUMO

Fax: 315-697-5867

E-mail: [email protected]

Internet: www.jumo.us

Application Notes for

Platinum-Chip Temperature Sensors

1 Introduction

Thin-film platinum-chip temperature sensors

from JUMO are basically formed from a

ceramic substrate on which a thinly struc-

tured layer of platinum is applied. A glass

layer seals off the platinum layer and thus

protects the temperature sensor to a certain

extent from chemical and mechanical influ-

ences.

During subsequent fabrication, the materials

that are used, and the type and method of

the processing, have a decisive effect on the

functionality and long-term stability of the

temperature sensors. In specific cases it may

be necessary to carry out qualification tests

for the selected design, to ensure that techni-

cal specifications for measurement accuracy

are met over the temperature range of the

application.

The following application notes have been

put together by JUMO as a result of many

years of experience in processing and han-

dling platinum-chip temperature sensors,

and are to be taken as recommendations.

2 Mechanical strength of

the connecting wires

2.1 PCA series

The connecting wires of the temperature sen-

sors can be subjected to the maximum ten-

sions shown below, without the functionality

being affected. Ensure that the wires are not

loaded laterally. Please refer to the table for

the maximum admissible horizontal tensile

load on one individual wire.

If the connecting wires have to be bent, then

care must be taken that the bend is not made

directly at the point where the connecting

wire enters the component sealing. If neces-

sary, use a suitable tool to keep the mechani-

cal stress away from this point. Continuous

force on the connecting wires, or tight bends

(kinking) must also be avoided, since this not

only increases the resistance (leading to a

systematically higher temperature indication)

but also makes the wires fragile and liable to

break under temperature stress.

2.2 PCKL series

These temperature sensors have terminal

clamps which are soldered on and especially

stiff. It is therefore particularly important that

the connections are not subjected to a side-

ways loading during processing. The maxi-

mum permissible horizontal tension is 10

newtons per terminal clamp. Bending or kink-

ing of the terminal clamps is not permissible.

Sensor Connection Tension

LAg-wire 5N

S Pt-Ni sheathed wire 10N

M Pt-Ni sheathed wire 10N

HPd-wire 6N

ENi-wire 6N

B 90.6121.4

3 Connection methods

Basically, the connecting wires of the temper-

ature sensors can be fabricated with all the

usual connection methods.

These are: soft soldering, brazing, crimping,

resistance welding and laser welding.

In practice, the relevant parameters for a

good connection vary according to the type

of wire used (see data sheet). It is therefore

advisable to make some test welds to obtain

the best results.

During welding or soldering, care must be

taken that there is no concentrated local

heating of the sealing points of the connect-

ing wires. If this occurs, the differences in

thermal expansion of the materials can lead

to strains or cracks and thus failure at some

later time. Furthermore, the maximum oper-

ating temperature of the temperature sensors

must not be exceeded during handling and

processing. It is recommended that a heat

shunt or similar tool is used to prevent exces-

sive heat reaching the temperature sensor via

the connecting wires.

Please also note that the nominal values

given are valid for the standard lengths of

connecting wires, whereby the point of mea-

surement is always 2 mm from the open end

of the connecting wires. Alteration to the

length of the connecting wires will therefore

change the resistance. This may have the

result that the tolerance class limits are no

longer met.

4 Mounting and

installation

4.1 Handling

Soft plastic clamps or tweezers should be

used for handling temperature sensors. Metal

pliers or coarse gripping/clamping devices

can cause damage to the temperature sen-

sors.

4.2 Potting, coating and gluing

During production processing of platinum-

chip temperature sensors, it is important to

avoid any mechanical stresses between the

temperature sensor and the potting com-

pound or casting resin, which can arise from

the difference between the coefficients of

thermal expansion of the various materials

that are used. It is therefore advantageous to

use potting compounds that retain some

elasticity after hardening. If not, it cannot be

ruled out that signal shifts may occur, or even

a total failure of the temperature sensor in

extreme cases. Potting compounds and

adhesives should therefore be qualified by

testing before being used for series produc-

tion. For instance, we recommend tempera-

ture cycling over the intended temperature

range of the application. Care must also be

taken that the potting or coating compounds

provide electrical insulation and are chemi-

cally neutral with regard to the temperature

sensor (ceramic substrate material [Al

]

and various glass materials).

The upper operating limit for the temperature

sensor must also not be exceeded during the

drying/hardening process. When the temper-

ature sensor is placed in the protection tube

and positioned, care must be taken that there

is sufficient clearance between the sensor

and the wall of the tube. If the sensor is

skewed or fitted too tightly, it may be dam-

aged.

4.3 Surface mounting

Platinum-chip temperature sensors can be

affixed to flat surfaces by using various types

of (SMD) adhesive, or double-sided adhesive

tapes. The usual curing/hardening methods

with UV radiation and/or heat do not create

critical stresses for the sensors. The notes of

4.2 must be observed.

4.4 Unprotected application

The sealing (glass covering) and connecting

wires of the sensors may be damaged if they

are exposed to a corrosive atmosphere,

especially in conjunction with moisture. Plati-

num-chip temperature sensors should there-

fore not be used in such an environment

without protection.

If bare sensors cannot be avoided, for

instance in HVAC applications, then we rec-

ommend using our M series, or sensors that

have been sealed by an additional protective

coating. In this case, it is absolutely vital that

the user carries out an appropriate qualifica-

tion test of the functionality and operating

life.

5 Thermal characteristics

5.1 Response times

JUMO measures the response times of the

platinum-chip temperature sensors in agi-

tated water with a flow velocity of v = 0.4

meters/second, and the average values are:

0.5

= 0.2 sec and t

0.9

= 0.4 sec.

Subsequent fabrication, such as installation

in a protection tube, will increase the

response times, depending on the nature and

mass of the materials that are used. Care

must therefore be taken to ensure good heat

transfer between the temperature sensor and

the protection tube. Heat-conductive pastes

and alumina powder have proved suitable as

heat-conducting materials.

5.2 Self-heating

In order to measure the electrical resistance,

a current must flow through the temperature

sensor. This current will heat up the tempera-

ture sensors by an amount that can be larger

or smaller, depending on external factors.

The size of the resulting error caused by this

self-heating depends on the applied power P

= I

x R, the amount of heat that is removed

by the medium being measured, the heat

capacity of the temperature sensor and its

surface. These specific characteristics are

combined in the self-heating coefficient E, so

that the error caused by self-heating is given

by ∆t = l

x R x E.

Self-heating coefficients of platinum-chip

temperature sensors are measured in air at v

= 2 m/sec and agitated water at v = 0.2 m/

1 2

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2009-07-07/00411240Page 1/2JUMO GmbH & Co. KGDelivery address: Mackenrodtstraße 14,36039 Fulda, GermanyPostal address:36035 Fulda, GermanyPhone: +

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